Category: Non-disposable

Posts that may have some sort of permanent value, or that I consider to be the best of what I have posted here.

G23-006: The sunniest spot in a shady yard? Part 1, geometry.

 

This is the first of two posts on finding the sunniest spot in a yard that has shade trees on either side.  This one uses geometry.  The next one will use time-lapse photography on a sunny day.

With any luck, both approaches will tell me the same thing.

If your yard is bordered by shade trees, locate the beds so that due south (180 degrees) splits the compass bearing from your bed to each line of trees.  This gives a surprising-looking result for my back yard.  It’s not at all what you’d naively think, just looking at the trees and the yard.

Garden bed location 1:  Wrong.

I started gardening seriously during the pandemic.  Temporary raised beds were made from recycled campaign yard signs and bamboo.  I placed those in seemingly-reasonable locations in my back yard. In part, they were filling in low spots on the lawn.  But it seemed like they were located so as to get the best sun.

I’m now getting around to putting in something more permanent.  This time, I’m not going to wing it, but instead want to know what spot in my back yard gets the most sunlight.

It’s not obvious.  I have tall trees on either edge of my yard.  And, interestingly enough, what appears to be the obvious solution — locate the garden beds in the middle of the yard, away from both tree lines — isn’t even close to being right.

So, eyeball a couple of birds’-eye views of my back yard, and see if you think I put the beds in roughly the right place:

Looks pretty good, doesn’t it?  You might even say that the location doesn’t much matter, because you’re going to get the same number of hours of sunlight almost anywhere in that back yard, regardless.  What’s shaded in the morning will be sunny in the afternoon, and vice-versa.

Problem is, an hour of sun is not an hour of sun.  Sunlight is much stronger around solar noon, and is weaker the farther you are from noon.  And, because the sun is due south at noon (in the Northern hemisphere), you have to know which direction is south, in order to judge what part of the yard gets the most solar energy.

Source:  Curtonics.com

You need to figure out the locations in your yard that place due south directly between those lines of trees.  Those locations get the greatest amount of high-intensity, near-noon sunlight.

To cut to the chase, you need to calculate where your potential garden site is, relative to the obstructing trees, and to due south.  The sunniest locations in the yard will have these two properties.

  • Due south (180 degrees) bisects the angle from your location to each side of obstructing trees.  E.g., find a spot where the bearing to one set of trees is 150 degrees (180 – 30), and the bearing to the other set of trees is 210 degrees (180 + 30).  That is, you get equal hours of morning and afternoon sun.
  • The angle from your location, to the obstructing trees, is as wide as possible.  For example, the location with a 60 degree spread above will get more total sunlight than a location with a 40 degree spread.   That is, you get as many total hours of sun as possible.

So now, take a look at my back yard, oriented so that south is directly down.  Do you want to change your prior answer?  By the look of the shadows, this is about 11 AM solar time.  Note that the left edge of the yard is already in sunlight.

 

Skirting a couple of pitfalls.

Let me take a brief break to mention a couple of pitfalls that can mess up your attempts to locate your garden in the sunniest spot on the yard.

Daylight savings time.  Man I hate having to get up at 2 AM to turn all the clocks forward, as required by law.  But the upshot is that solar noon occurs around 1 PM during daylight savings time.  For example, on the hourly insolation graph above, peak insolation occurs around 13:00, or 1 PM.  That’s not a mistake, that’s just daylight savings time.  So if it’s summer, and you look to see where the shadows fall at noon, you’re screwing up.  Because noon, daylight savings time, is actually 11 AM solar time.

Above:  Compass set up for 10 degrees west magnetic declination

Magnetic declination.  Declination is the extent to which magnetic north — where the compass needle points — deviates from true north.  Because of magnetic declination, you can’t simply use the raw readings from a standard magnetic compass in order to locate your garden in the right spot.

If you have a compass made for use on land, and it’s anything but the most basic compass, chances are you can adjust the compass to account for declination.

You can find the magnetic declination for your locality at the US Geological Survey, among other places. Currently, magnetic declination at Vienna VA is about 10 degrees west.  That means that the compass needle actually points to a heading of about 350 degrees, not 360 degrees (true north).  That’s about 2.5 degrees further west than when I was a kid in the 1970s.

Magnetic declination is one of those incredibly simple topics that always manages to get an incredibly opaque explanation.  But as long as you have a compass that can be set to account for your local declination, it’s really simple.  The picture above shows a compass set up for 10 degrees west declination.  Despite the fuzziness of the photo, I think it’s obvious that the compass body has been offset 10 degrees relative to the degree ring.  When the needle points to 350 degrees (10 degrees west of true north), 360 or 0 on the degree ring shows you true north.

The sunniest spots in my back yard are directly next to the trees.

I can now take Google Earth, and start drawing in the angles between various backyard locations, and the ends of the lines of shading trees at the sides of the yard.  It’s a little crude, but the conclusion is inescapable.  I put the temporary beds too close to the middle of the yard.  For the most solar energy possible, they ought to be almost under the trees at the side of the yard.  Like so:

Which, to be honest, I would not have guessed, just eyeballing it.

Over the coming weekend, I’ll set up a stop-motion camera to film my back yard for one sunny day.  With that, I should be able to validate that the area that gets the most solar energy is the one outlined.  And I should be able to determine just how much energy I lose if I move away from that optimum spot.

Post #1711: State-of-charge hypermiling and a generalized theory of pulse-and-glide

Why pulse-and-glide saves gas.

Gasoline engines run most efficiently when under a fairly heavy load.  Load them too lightly, or too heavily, and their efficiency drops.

Below is the “efficiency contour” of a hypothetical 2 liter Atkinson cycle engine. Engine RPM is on the X-axis.  Engine load (output) is on the Y-axis.  The labels on contour lines are percents, and show the fraction of the energy in the gasoline that is converted into motion by the engine.  Those contour lines define a sort of hill, with the peak of the hill — maximum efficiency — occurring when this engine is running around 2500 RPM, putting out about 100 horsepower. And converts just shy of 39% of the energy in the gas into usable power.

Source:  Kargul, John & Stuhldreher, Mark & Barba, Daniel & Schenk, Charles & Bohac, Stanislav & McDonald, Joseph & Dekraker, Paul & Alden, Josh. (2019). Benchmarking a 2018 Toyota Camry 2.5-Liter Atkinson Cycle Engine with Cooled-EGR. SAE International journal of advances and current practices in mobility. 1. 10.4271/2019-01-0249. Accessible though this link.

The engine modeled above is a 2.0 liter Atkinson-cycle engine.  That’s just a bit bigger than the 1.8 liter engine that’s actually in the Prius Prime.  But it’s close enough.

Below, there’s the crux of the problem.  Much of the time, the engine is inefficiently lightly loaded.  I’ve marked the power required to cruise on level ground at a steady 55 MPH in a Prius.  The car only needs about 12 HP.  (I infer this from the ~12 KW of power drawn to keep the car at that speed in electric (EV) mode.   That power, less about a 20% loss in the electric motors, is the energy required at the wheels to keep the car moving forward at that speed.

And so, if you cruise along at a steady 55 MPH on the gas engine, even though the car won’t be burning a huge amount of gas, what little it burns will be burned inefficiently.

Instead of running that engine steadily at 12 HP output, you could alternatively run it hard — run it briefly at 100 HP — then shut it off.  And repeat as necessary.  That’s pulse-and-glide.

And that’s why pulse-and-glide saves gas.  You extract energy from gasoline as efficiently as possible, by running the engine under heavy load.  And then you match the engine output, to the average power required by the car, by cycling the engine on and off as needed.

Traditional pulse-and-glide makes you a rolling hazard.

With traditional (or kinetic-energy) pulse and glide, you first run the gas engine and speed up.  Then switch it off, coast, and slow down.  And repeat.

Practically speaking, this is of almost no value on the public highways, because this makes you a nuisance to other drivers.  It makes you into a rolling traffic hazard.

Potential energy pulse-and-glide requires the right terrain.

Speeding up, however, is not the only way to store the output of the car’s engine.  Going up a hill works just as well.  You store that excess output in the form of potential energy (height) instead of kinetic energy (speed).  Apply gas on the uphills, coast with engine off on the downhills.

I can attest that this most definitely works.  This is how I achieved my last two 80-MPG all-gasoline (no energy from the grid) road trips.

Needless to say, this only works where you have significant hills.  Ideally, hills large enough that the car will maintain the posted speed limit on the downhill with no or minimal energy input from the drive train.

A new/old concept:  State-of-charge pulse-and-glide.

Both methods described above can be done by a standard gas car.  No electric motors are required.  In fact, in a Prius, you achieve maximum efficiency under either method if you never use your electric motors.  (Using the gas engine to charge the battery, then run the motors, wastes about 30% of the power produced.)  Champion Prius hypermilers actually shift the car into neutral on the “coast” phase, specifically to avoid moving electric current into or out of the battery via the motor/generators.

But a plug-in hybrid electric vehicle (PHEV) like the Prius Prime has yet a third option, which I’m going to call state-of-charge pulse and glide.

To be clear, what I’m about to describe is something that the car does, on its own, anyway.  The only question is whether you can modify your driving behavior to take exceptional advantage of it.

If you use the gas engine to charge the battery, then run the electric motors, that wastes about 30% of the energy produced by the gas engine.  So, at first blush, it seems like you’d want to avoid using those electric motors.

But, if you charge that battery at the peak of the gas-engine efficiency curve, that means the electric motors are using up your gas with somewhere around (0.7*38% = ) 27% efficiency.

This leads to the section that I’ve labeled “EV carve out” above.  Roughly speaking, if the driving situation requires less than about 25 KW of power, it’s more efficient to run in EV (electric-only) mode, as long as you can later recharge the battery at relatively high engine load.  (So that the recharge happens near peak gas engine efficiency.)

In the Prius Prime, assuming this engine chart is a reasonable proxy for the actual Prime 1.8 L engine, that has the following practical implication for running the car in hybrid-vehicle (no-grid-power-used) mode.  If you can, you should run on electricity-only up to a current draw of about 90 amps.  That’s the point at which the electric motors, less their inherent 20% loss, are producing about 25 KW of power. That’s the point where switching to gas propulsion is more efficient.

But the closer you get to that 90 amp limit, the less advantage electricity has over gas, and the less gas you are saving.  So, from a battery wear-and-tear perspective, it’s probably best not to push it that far.  You will likely get the bulk of your savings with a more conservative limit of (say) 50 amps, or roughly a “2 C” discharge rate.  (The rate at which the entire EV battery would be dead in half an hour.)  Assuming the car will let you do that, in hybrid mode.

So, a conservative rule-of-thumb is that a power output of somewhere around 17.5 KW (25 HP) is where you should try to flip the car from gas to electric and back.

To be clear, the car does something like this on its own.  At low power demands, it shuts off the gas engine and used the electric motors.

What I have noticed, however, is that there’s considerable hysteresis in the car’s decision.  In particular, once the gas engine is on, it tends to stay on until power demand gets quite low.

So I believe that driver intervention can improve mileage, using (e.g.) terrain anticipation.  If you’re coming to a stretch of road with likely low power demands — cresting a hill, starting a slow deceleration, or just coming up to a level stretch — you may be able to beat the Prius’ internal algorithms.  Conversely, when you see a high-power-demand situation coming up — a hill, say — you can flip the car into gas mode before it begins to bog down in electric mode.

My simple initial rule-of-thumb will be a 50-amp cutoff.  When in hybrid mode, drive the car on the electric motors up to 50 amps current or low state-of-charge cutoff, whichever comes first.  Anything over 50 amps, nudge the accelerator to kick the car into gas mode.

Edit:  I decided to do a little acid test of the concept.  As every driver knows, the worst trips for a gas engine are short, around-town jaunts.  I decided to do a little run to a couple of stores, in hybrid vehicle mode, total trip of about 8 miles, divide into three legs with stops in-between.  After the mandatory gas-engine warm-up period, whenever the gas engine came on/power was needed, I loaded the gas engine heavily.  I gave it enough throttle to bring it immediately to the “power” zone on the dashboard.  But, once up to speed, I let off the accelerator to shut the gas engine off, and drove for as long as feasible on electricity only, respecting a maximum draw of 50 amps.

Results:  71 MPG.  And it was clear that if I’d had a longer distance between stops, that would have increased. 

One short trip does not prove the concept.  And the Prius chastised me soundly for those hard accelerations, basically giving me a flunking score on the eco-meter.  Nevertheless, I consider this first test to be encouraging.

By the book, and by the dashboard readouts, I was doing everything wrong. And yet, it’s hard to argue with the MPG.

Edit 2, 2/19/2023.  Not so fast.  Building on the above, I went to a local disused office building and circled the parking lot.  Roughly a 1.3 mile circuit, 25 hour speed limit, three full stops per loop.  On one set of loops, I tried this hypermiling approach.  On another set, I drove gently, then used the “charge” function to bring the battery state-of-charge back to its original level. 

Results:  In both cases, I got about 75 MPG.  Which, in hindsight, may simply be what the Prius Prime gets, driven in hybrid (gas-using) mode, around 25 MPH.

I think the moral of the story is that I’ve done so little around-town driving in hybrid (gas-using) mode that I’m not sure sure what sort of gas mileage I should expect as a baseline.

Conclusion

Anyone who has ever used the Prius cruise control in hilly country knows that it’s quite “reactive”.  It doesn’t anticipate the hills, but instead holds speed steady, then pushes the car far out onto the power curve in an attempt to maintain speed on the uphill.  For that reason alone, I don’t use the cruise control on hilly roads, as I feel that I can drive the car more efficiently in manual mode, making some modest adjustments in speed on the downhills and uphills.

Similarly, I’m betting I can squeeze a little extra mileage out of the car, in hybrid mode, by manually selecting the point of switch-over between gas and electric propulsion, and pushing the gas engine at high load to maximize efficient use of gasoline.  Then, once at speed, or over the crest of a hill, lifting my foot off the gas briefly to shut the gas engine down, and continuing in electric-only mode as feasible.

You need an extra bit of instrumentation to be able to do that well.  I’m using a Scangauge 3, which will show me quantities such as battery current, engine RPM, and engine output.

What makes this work, as a form of pulse-and-glide, is, of course, the traction battery.  That’s where the excess power production of the gas engine is stored if not needed.  So the right way to view this is state-of-charge pulse-and-glide.  Instead of letting the speed vary (kinetic energy), or the height vary (potential energy), you let the battery state-of-charge vary (electrical energy).

Same concept either way, you just choose a different place to store the excess power output of well-loaded gas engine.  With different implications for how usable pulse-and-glide is, in actual highway traffic, for a given terrain.

Finally, I note that there have been recent patents issued for systems that would automatically pulse-and-glide large trucks, based on a system that anticipates changes in terrain.  They seem to be characterized as a more fuel-efficient form of cruise control.  With everything in modern cars being controlled by a computer, it doesn’t seem too far-fetched to think that some form of automated pulse-and-glide — a fuel-saving cruise-control mode — might eventually become a standard option on vehicles capable of doing it.

With that point of view, driving a gas engine at a constant, low engine load is something of a relic of the past.  It dates to the era when there was literally a metal cable connecting your gas pedal to the throttle body on the carburetor.  With everything computer-controlled these days — and carburetors a thing of the far distant past, for cars — it doesn’t seem like a stretch to ask your computer to do your energy-saving pulse-and-glide for you. As long as you have some safe way to store that excess gas-engine output.

Post #1710: The best thing that ever happened to all my friends’ gas mileage.

My wife bought her first Prius in 2005.  We tend to forget, but there was a lot of hatred expressed toward that car, at that time.  Which sounds hilarious now, but is true.  There was also disinformation spread about that car, similar to the disinformation you’ll hear these days regarding electric vehicles.  E.g., that the Prius had single-handedly ruined Sudbury, Ontario due to the need for nickel for the battery.

There was also a lot of just-plain-ordinary denial.  That car got an EPA-rated 46 MPG, which, for the time, and the size of the car, was absolutely outstanding.  This was a time when you could not find a traditional gas car with similar interior volume that broke 30 MPG.

It was, as I have noted before, alone in its level of efficiency.  That’s expressed below by an index combining gas mileage and interior volume.  (This is my calculation, from EPA mileage data.)

At that time, if you were willing to drive a small car, and required that it get at least a whopping 35 MPG overall, your choices were:

  • Honda Insight (basically, a tiny 2-seater).
  • Honda Civic Hybrid (as shown on the chart above).
  • Three small VW models with 35 MPG turbo-diesels.

This per the federal website fueleconomy.gov.

And yet, I used to joke that my wife’s Prius single-handedly improved the gas mileage of the U.S. automobile fleet.  Because, every time we mentioned 46 MPG, the universal response was, “Big deal, I get almost that good of a mileage in my fill-in-the-blank.”  That Prius was the best thing that ever happened to the gas mileage of all of our friends’ cars.

The first year we owned that car, we heard about all kinds of mythical non-hybrid vehicles that easily got over 40 MPG.  Easily.  All the time.  Without all that fancy hybrid nonsense.

In reality, none of these folks had a clue what they were talking about.  None had actually carefully tracked mileage.  Most had some impression of some road trip they once took where they think they got great mileage.  Nobody was talking about city mileage.  And so on.

But they all knew that hybrids were just so much hype.

As I continue to learn how to drive my wife’s 2021 Prius Prime for greatest fuel economy, I keep setting new personal bests.  Most recently, we drove out to a local scenic byway (the Snickersville Turnpike) and back.  Door-to-door, using “hybrid mode” (no energy from the grid), we managed to get 82.4 MPG over the course of the 80-mile round trip.

That was a mix of 55+ MPH urban arterial highways, country roads, and then small-town streets.  So, no high-speed interstate driving.

Back in the day, people could fool themselves into thinking that their non-hybrid vehicle was just about as efficient as a Prius.  Even though the U.S. EPA clearly said otherwise.

But this most recent generation of Prius, when driven with an eye toward best mileage (Post #1624), gets such eye-popping numbers that I don’t think you can kid yourself any more.  This is now my second trip where I’ve ended around 80 MPG, driving the car in hybrid mode (i.e., not using energy from the grid.)  Even our interstate trips now routinely yield high-60’s MPGs (admittedly, without the extreme speed limits present on Western interstates.)

And, separately, more than 70% of our miles are run purely on electricity from the grid.  Which means the 65-to-80 MPG observed in hybrid mode is our version of gas-guzzling.  In “EV mode”, using the battery and not the gas engine, we manage somewhere around what the EPA would term 150 MPGe.

This isn’t by way of bragging.  It’s by way of setting the record straight about what’s routinely and reliably available these days.  For not much money, as new car prices go.

I continue to read articles about how hard it is to move to electric transport, what a huge expense it entails, and so on.  And, yeah, you can make it hard, and you can make it expensive, and inconvenient.

But none of that has to be true.  Buy a quality plug-in hybrid electric vehicle (PHEV).  If you’re like us, you’ll get most of the benefits of electrical transport and none of the drawbacks.  Sure, you have to have some faith in the technology.  You need to learn the do’s and don’t of taking care of that big battery.  In a few areas,  electricity is currently a more expensive fuel than gas, by a modest amount.  But as far as I can tell, hybrids started out pretty good, and they just keep getting better.

I’m no longer satisfied when I only get 80 MPG, driving my wife’s hybrid.  And I find that absolutely mind-blowing.

Post #1707: Nobody offers a warranty on the electric range of their plug-in hybrid vehicles?

 

Edit 2/11/2023:  I grossly underestimate the replacement cost for a Prius Prime lithium-ion battery.  Per this thread on Priuschat, the cost of new Prius Prime battery, from the dealer, is $12,595.  Others suggested the dealer took some markup, as the list price from Toyota is just under $10,000.  I say, potato, potahto.

In round numbers, the cost of a new replacement battery is 43% of the cost of a brand-new Prius Prime, base model, current MSRP $28,770.  As a footnote, literally none were available in North America, and the battery has to be shipped directly from Japan.

I should put in the usual EV-weasel-wording:  By the time the battery dies, there will be plenty of good-used batteries in junkyards, from wrecks.  That did, in fact, happen with the original Prius NiMH hybrid battery.  Plus, there may be much cheaper aftermarket replacements at some point.  And so on.  But right here, right now, what I cited are the hard numbers for battery replacement cost.

Original post follows.

Only Volvo offers any warranty on your plug-in hybrid electric range, near as I can tell.

And I think I have finally nailed down why that is.

A typical battery guarantee for a fully electric vehicle (EV) is that a car will lose no more than 25% of range in 8 years/100,000 miles.

Based on research shown below, using actual driving behavior, for a Prius-Prime-like plug-in hybrid electric vehicle (PHEV), you would expect about 5% of batteries to fail, under that 8-year, no-more-than-25% loss definition.  Just from normal wear-and-tear, as-typically-driven.

So, my guess is that PHEVs don’t get those guarantees because manufacturers would end up replacing too many batteries.

All the more reason to treat your battery gently.

Background

Last week, I found out that my wife’s Prius Prime had no warranty on its electrical range.  Currently, as we drive it, we get mid-30-miles on a charge.  But if that drops to zero, tough.  As long as the car will still run as a hybrid, they battery has not “failed” under Toyota’s 10-year/150,000 mile warranty.

So I got curious.  I already have a list of all 2022 plug-in hybrid electric vehicles (PHEVs), from a just-prior post.   I decided to look up the warranty information for as many manufacturers as I could find.

Here’s the results.

Volvo offers a 30% loss-of-range warranty.  If you lose more than that, during the eight-year warranty period, they’ll fix it.

Near as I can tell, none of these other manufacturers offer any warranty whatsoever, on the electrical range of their PHEVs.

Toyota
Kia
Porsche
MINI
Ford
Chrysler
Mitsubishi
Jeep
Hyundai (I think)
BMW (but maybe they decide case-by-case?)

The Hyundai warranty covers EVs, PHEVs, and hybrids, and in separate places says that it definitely covers loss of range, and that it definitely does not cover loss of range.  Your guess is as good as mine, but I’m guessing they cover range for EVs (as required by law) but not for PHEVs.

Originally, I could not understand why Toyota offered no PHEV range warranty.  That situation has now improved.  I’m now baffled why almost nobody offers a PHEV range warranty.

Unfortunately, I think that “no PHEV range warranty” is the industry norm  for precisely the reason stated in the Toyota warranty documents:

 

I’m an economist by training, and I find it this interesting, I guess. When there’s a de-facto industry standard, there’s usually a reason for that.

And I think I understand why no-PHEV-range-warranty is the industry standard.

How many would “fail” under normal driving conditions?

I’ve been searching for an answer for this for the better part of a week.  I posted my thoughts on preserving battery capacity on a chat side dedicted to the Prius (PriusChat), and with a few exceptions, got met with derision.  For sure, nobody there had ever heard of a Prime or the prior version (Plug-in Prius) showing any signs of premature loss of range.  Almost nobody thought that any sort of battery-protecting behavior was necessary.

I finally came across what I believe is a realistic projection of the fraction of Prius-Prime-like vehicles that would fail under the typical EV warranty of no more than 25% range loss in eight years/100,000 miles.

That’s:  Comparison of Plug-In Hybrid Electric Vehicle Battery Life Across Geographies and Drive Cycles, 2012-01-0666, Published 04/16/2012, Kandler Smith, Matthew Earleywine, Eric Wood, Jeremy Neubauer and Ahmad Pesaran
National Renewable Energy Laboratory, doi:10.4271/2012-01-0666

They used actual driving data from about 800 trips taken by Texans in PHEVs.  The then extrapolated that to eight years of driving behavior.  Their model is not quite perfect, as the modeled vehicle only provides a 10% “buffer” at maximum allowable charge, while the Prius Prime provides 15%.  On the other hand, for the key chart, they did not include (e.g.) the effects of high temperatures on battery life.  (So, no parking your car in the sun in this model, so to speak).

Here’s the key graph, where the most Prius-Prime-like vehicles is the PHEV40.

Source:  Cited above.

In a nutshell, only counting the wear-and-tear from normal driving and charging, they expect the average user to lose 20% of range by the end of the eighth year.  And about 5% of users would experience in-the-neighborhood-of 25% range loss.

If they were to throw in the effects of variation in climate (hot climates kill batteries quicker), and variation in practices regarding storing the car fully charged (which also kills batteries quicker), I might guess that around 10% of drivers might exceed that 25% loss threshold within an eight-year warranty window.

To put that in perspective, car manufacturers as a whole spend about 2.5% of their total revenues on warranty repairs (reference).  A ten percent failure rate of this part, replaced at new-battery cost shown above, would by itself account for (roughly) 4 percent of Toyota revenues from Prius Prime sales.

As far as I’m concerned, this solves the mystery of the missing warranty.  (Almost) nobody offers anything like the standard EV warranty, because if they did, they’d have to replace an unacceptably large fraction of batteries under warranty.  And that would lead to an unacceptably high warranty cost.

All the more reason to avoid unnecessary wear-and-tear on a PHEV battery.

Post #1706: When is electricity the cheaper home heating fuel?

 

Today the Washington Post had an article on electric heat pumps displacing oil and propane in Maine.  Not only do modern heat pumps work reasonably well in that cold climate, but they were reported to save a lot of money, compared to oil or propane furnaces.

I had a hard time believing that they were big money-savers, as electricity rates in New England are pretty high.  So I decided to check the math, using reasonably current prices and some reasonable guesses for technical performance of each type of heating.

The answer is yes.  If you replace on old, inefficient oil stove with a heat pump, you should expect to cut your heating bill in half.  Probably more interestingly, not even a modern high-efficiency oil furnace can compete with a heat pump, at Maine’s prices.

But I note one fact that makes Maine’s situation different from that of Virginia, where I live.  I don’t think you can get natural gas most place in Maine.  It would be slightly cheaper to heat with natural gas, at national average prices, if you used a 95% efficient natural gas furnace.  In Maine.  Given Maine’s high electricity prices.

As a final footnote, near as I can tell, the interesting thing about these new generation heat pumps is that they will work in extreme cold.  Near as I can tell, they are not hugely more efficient that the prior generation, as long as temperatures are moderate.

But what about electricity versus natural gas, in Virginia?

Source:  Clipart Library.com

My home heating system was designed by the internally-renowned HVAC engineer Rube Goldberg.  The original 1950s gas-fired hot water baseboard heat is now the secondary heating system.  That’s run by a 95%-efficient gas furnace, which also provides domestic hot water.  Layered over that is the new primary heat source, consisting of two elderly ground-source heat pumps, fed by just over a mile of plastic pipe buried in the back yard.

I have pipes, wires, and ducts running every which-away.  In the house, throughout the yard.  In the attic.  Under the slab.  Up the outside of the house and over the roof (no joke).

It works.  Except when it doesn’t.  As was the case this week, when the super-efficient gas hot water heater failed.  That finally got fixed today.  Which is what got me thinking about this.

From the standpoint of carbon footprint, after I put that high-efficiency gas furnace in ten years ago, I was more-or-less indifferent between electricity and natural gas as the fuel source. Pretty much the same C02 per unit of heat, either way.

But as the Virginia grid has more than halved its carbon footprint over the past two decades, electricity has become by far the lower-carbon option.  (Underlying source of data for both graphs is the U.S. EIA).

Every once in a while I revisit the issue of cost, mostly because natural gas prices fluctuate all over the place.  Using the same framework as above, here’s the current match-up between my ground source heat pumps (with assumed coefficient of performance of 3.3), and my 95% efficient gas furnace.

Turns out, at current prices, and with my setup, electricity now beats the pants off natural gas, cost-wise.  Not hugely different from the situation for oil in Maine.  I didn’t expect that, and I’m pretty sure that’s a consequence of currently high natural gas prices.

In any case, it’s nice when you can do well by by your bank balance by doing right by the environment.

My only real takeaway is that I should minimize my use of gas-fired secondary heating, within reason.  I figure if the citizens of Maine can get by with nothing but heat pumps, I should be able to do that as well, in the much milder climate of Virginia.

Post #1696: An historical note on the current Xbox kerfuffle

 

A well-known energy hog of long standing

When the recent manufactured controversy over the Microsoft Xbox hit the papers, it resonated with me.

Probably 15 years ago, we bought a gaming console for our kids.  (For the kids, of course, because we adults would never consider wasting time playing video games.)

We bought a Nintendo Wii.  Not due to the quality of the gaming, but because the Wii console used about one-fifth the energy of the Xbox and similar alternatives.  (Ask me what screen I finally got to on Wii Tanks.)  The Wii had a lot of other interesting features — not the least of which was the Mii parade above.  But the main reason I picked it was that it had a vastly lower carbon footprint than the alternatives at the time.

At the time, the characterization of Xbox energy use was that leaving an Xbox running was like leaving your fridge door wide open.  It literally used as much power as the typical American fridge.

That does not appear to have changed in the past couple of decades.  Exactly how much energy a gaming console uses depends on what you’re doing. But it’s clear that running a graphics-intensive game, on an Xbox, and using some modest-sized display, could easily consume 300 watts.  

Here’s a site with a nice table showing typical ranges of energy consumption for home gaming consoles.  In particular, they have a nice table for the PS4, showing that the difference between letting the machine run, unused, and putting it on standby, is about 85 watts.  That matches my recollection for the Xbox.

And, doing just the tiniest bit of math, if you let that game console run at idle all the time (i.e., showing the menu), that will cost you about 750 KWH per year, compared to powering it down to standby mode.  That 750 KWH is, in fact, more than the average U.S. fridge, per year.

The upshot is that, as I recalled, if you don’t enforce turning your Xbox off, but instead just leave it idling, the additional electricity cost is more than the cost of running a refrigerator.

What did Microsoft actually just do?  Sleep versus Shutdown, or about 130 KWH per year in energy savings.

As is typical with modern news-righteousness, everybody seems to start yelling before you can get a clear picture of what just happened.

If you want a clear explanation, start here.

At issue is the difference between Sleep mode (with instant-on), and Shutdown mode (where it takes about 15 seconds for the Xbox to reboot).  Just as with your laptop, one of those keeps everything in memory, keeps memory warm, and uses more power.   The other one writes things off to storage, then more-or-less turns the machine off.

Sleep consumes perhaps 15 watts, while shutdown mode consumes just 0.5 watts. Which doesn’t sound like much, but for an Xbox continuously plugged in, the 15 watt Sleep mode consumes about 130 KWH per year more than the 0.5 watt Shutdown mode.

Just FYI, that’s enough electricity to power my wife’s Prius Prime for about 750 city miles of driving.  At the prices I pay in Virginia, that’s about $15 worth of electricity per year.

In the past, Sleep was the default mode.  But starting in March 2022, Microsoft change the default to Shutdown, rather than Sleep, for newly-manufactured units.  So, to be clear, this new default has been in place for almost a year, on newly-purchased units.

The current controversy arose because Microsoft is updating the software on older Xbox units to make them match the standard that has been in place for about a year, for new units.  That is, they are going to make Shutdown the default.

Users can override that if they wish.

In my experience, you don’t scrape the bottom of the barrel until the barrel is empty.

I don’t know how the party of Teddy Roosevelt ended up being the pro-energy-consumption party.  But that seems to characterize the Republican party today.  Coal is good.  Renewables are bad.  Energy use is good.  Energy conservation is bad.

At root, this is a controversy about a manufacturer choosing to make the software on older gaming consoles match the software that it has put on consoles manufactured for the past year.  Mainly, this changed the default “off” setting from Sleep to Shutdown, which I calculate should save about 130 KWH per year per unit.

Near as I can tell, Microsoft updates the software on my computer any damn time it pleases.  And I actually depend on the computer to get along in the real world.  How on earth this update to gaming-console software became such a cause célèbre among the Right, I cannot even begin to fathom.

But, ultimately, I think it’s a good sign.  If that’s the biggest thing they have to complain about, then things must be going pretty well.

Post #1693: Razor blade wear and tear, the final piece of the puzzle.

 

OK, I lied.  My last post was not my final post on shaving.

To complete the analysis of factors affecting razor blades, I need to document normal variation in beards.  In short:  It’s huge.  All other things equal, that almost certainly leads to huge variation in razor blade life.

This scholarly article will probably tell you more than you ever wanted to know about beard hair.   A key sentence is:

The density of beard hair follicles varies with facial area and ethnicity. Values range between 20 and 80 follicles/cm2

I interpret that to mean that, within normal variation, some guys have four times as many beard hairs (per skin area) as others.  All other things equal, that’s going to generate four-fold variation in razor blade longevity.

There is further variation in hair thickness, stiffness, shape, and so on.

With that much background variation, there really is no such thing as normal razor blade life.   There’s only what’s normal for you, and what you can plausibly do to extend it.

The only shaving technique studied in that article is wetting (hydrating) your beard.  Which I think anybody who shaves with a blade understands to some degree.

The force needed to cut a beard hair is reduced by about 20% within the first minute of water contact. After four minutes, the cutting force is reduced by 40% and does not significantly decrease further with longer hydration

This correlates well with the standard advice you’ll hear from shaving experts, which is to let your shaving soap or cream sit on your face for a minute or two before you shave.  (Both shave cream and soap lather contain water.)

Interestingly, I can find zero scholarly evidence that the fat (e.g., stearic acid) in shaving cream does anything to soften hair.  And yet, I have found that shaving cream extends blade life, compared to shaving with soap, even though both methods result in hydrating the beard prior to shaving.  Moreover, so far (shave #10 on the same blade, today) it extends blade life far beyond what you might expect from the 40% reduction in cutting force cited above.  And, all major brands of shaving cream or gel contain one of two fatty acids as their main component.

Maybe that’s strictly a skin softener?  Maybe a lot of the wear-and-tear of shaving comes from the skin, and not the hair?

Beats me.  Whatever the underlying mechanism is, it seems to work.  And every manufacturer of shaving cream seems to include it as the main ingredient after water.

I guess, now, I really will call it a day on posts about shaving.

That’s not to say that I’ve exhausted the topic.

It’s more than I’ve exhausted my willingness to track down all the nutty claims that are made about shaving and razor blades.  Every time I look, I find another one.  Today, it’s a patent claiming that dipping razor blades in 12% to 20% citric acid will extend their life at least five-fold, by preventing the formation of “mineral crystal buildup”.

Edit:  Well, as it turns out, upon further research, that’s not so nutty after all.  See Post #1699 on how water spots (calcium carbonate deposits, or “mineral crystal buildup”) can coat the razor edge and so dull the blade.

Let us never forget that you can keep your blades sharp forever by keeping them in a pyramid-shaped object.  But only if you orient it exactly with the earth’s magnetic field.  And yeah, there’s a patent for that one, too.

Post #1692: Strop-a-Palooza, the finale. Use a knife steel to strop stainless-steel razor blades

 

Edit:  Nope. See below.  Honing a worn stainless-steel blade with a knife steel made the edges look a lot better.  But the blade still shaves badly.  And I have no idea why.

I think I’ve figured out a possibly-effective way to strop or hone a stainless steel razor blade.  Possibly.  Use a sharpening steel.  The thing pictured at the top of the post.

Don’t use an abrasive (e.g., diamond) steel.  Use a common carbon-steel knife sharpening rod.  The last post demonstrated that you can’t abrade much off the edge before the blade is ruined for shaving.

Use the “pull” technique.   Weirdly enough, half the experts on Youtube pull the blade across the steel.  Half push the blade, as if you were cutting into the steel.  That suggests to me that this works either way.  And pulling a razor blade is going to be a lot easier.  Like this technique (Youtube link).

Hold the blade at very shallow angle to the knife steel.  Start at one side of the edge, and pull it across and up the steel.  Flip and repeat as often as you want, because, based no seemingly expert authority, it’s almost impossible to over-steel a knife edge.

I’m not entirely sure this works, but it’s the best I’ve come up with, and it seems to do something.

For sure, this does nothing for any chips in the blade edge that are large enough to be visible with a microscope.  So if a blade edge is badly eroded, honing it in this fashion isn’t going to fix it.  But, that’s fair, as honing or stropping isn’t supposed to repair a damaged cutting edge.  Those really just clean up the very final finish on an otherwise sound cutting edge.

But, maybe it does something to the very edge of the blade.  After vigorous stropping in this fashion, the stropped edge of a razor blade feels sharper when run across the ball of the finger.  So much so that I can tell one edge from the other in a blind test.

Unfortunately, I have no other evidence that this is actually doing anything.  Whatever is happening at the very knife-edge of the steel is far too small for me to see with my crude microscope.  My home-made sharpness tester had too high a variance to tell me much.  And, with one blind shave test, I can’t really feel any difference in shaving.

Edit:  Finally, after 11 shaves with one Personna blade and Barbasol, I judged the shave to be inadequate.  Here’s a contrast of the worn blade and a new blade, after that 11th shave.  You can clearly see that the new edge is perfectly straight, but that the worn edge has quite a ragged appearance. 

(Parenthetically, you can see what a difference shaving cream makes relative to Dove soap.  Unlike my used blades after soap shaving, on this blade there are no huge nicks in the edge, just an uneven razor edge.)

This amount of edge wear is enough to cause me to change to a fresh blade. 

I did my best to see whether or not the blade was any narrower, per my prior experiment in sharpening a blade.  As far as I tell, it’s not. So I’m not wearing out the blade by making it too small to give a good shave. (If that were true, there would be no point in proceeding, because I can’t restore the blade to its original width.)  I’m wearing out the blade by giving it a ragged razor edge.

So, what the heck.  I carefully steeled/honed that worn blade.  Held the blade in my hand, and gave it about ten strokes across the steel, on each edge, flipping the blade with each stroke. 

Below you see two views of the same pair of blades after passing the worn blade over the knife steel.  By eye, the worn edge now appears somewhat less ragged.  Not perfect, but significantly straighter.  Which, I think, is roughly what a knife steel ought to do.  Clean up the very tip of the razor edge of the blade.

I still don’t know if this improved the blade enough that it can still used.  But I’m going to try shaving with it tomorrow.  (Honestly, it’s hard even to be sure that I’m not kidding myself about the steeled edge being straighter.)  Shaving is clearly going to be a subjective test, and if I’d thought about it, I’d have steeled just one edge, so I could do a blind shave test of one edge versus the other.  But that’s water over the dam at this point.

I’ll re-edit this one more time, after I’ve shaved with the worn-and-carefully-steeled blade.

Final edit:  Still doesn’t shave worth a damn.  I have no idea why. 

The blade remains the correct width.  I pulled out a micrometer, and the worn blade is exactly the same edge-to-edge width as a new blade (to within the 0.01 mm resolution of the tool.) 

The blade edge looks good.  Under magnification (with a cheap USB microscope), the blade edge is nice and straight.  I’m hard pressed to tell the used blade from a new blade.

The upshot is that I have no clue why the blade won’t shave.  Possibly the blade wear goes on at a scale that I just can’t see with my current level of magnification?  I hate to leave it like that, but I can’t see any reason why this blade no longer shaves well.  But it doesn’t.

That said, this brings my razor blade deep-dive to closure.  The final question was whether or not there was anything you could do to re-sharpen a stainless-steel blade.  Edit: My answer is, yeah, maybe.  Try using a knife steel.  As of this writing, my answer is no.  As with stropping on leather, I can use a knife steel to clean up the edge, but I can’t make the blade shave well again.

Finally, I am virtually certain that all the methods you may see on the internet, for stropping a razor blade, are simply folklore.  E.g., rub the blade on the inside of a glass, strop it on denim, and so on.  These probably date back to the era of carbon-steel blades.  I’m pretty sure stainless is just too hard (or wear-resistant) for those to work.

Even a proper leather strop merely shined up and cleaned up my blade edge.  It didn’t make it any sharper or better for shaving.  Experts say that you need to use abrasives, if you plan to strop stainless on leather.  My guess is that this is good advice.  But unlike a knife blade, you can’t afford to lose even a smidgen of metal off the edge of a razor blade, or it will no longer function in a safety razor.  So I don’t think abrasives are the answer here.  But I have to note that I have not actually tried loading up a leather strop with the proper stropping abrasive and having at it.

So, the only other object commonly used for cleaning up the edge of a stainless blade, without abrading it, is a knife steel.  Knife steels definitely work on stainless knives.  There’s no reason to think they won’t work on stainless razor blades.

And, near as I can tell, yes, steeling a stainless razor blade in this fashion does something.  Kinda.  I guess?

So with that, I’m calling it a day.

 

Post #1691: Strop-a-Palooza, Part 3: Fool’s errand?

 

I’m ready to call it quits on trying to strop a stainless-steel double edge razor blade.  For now, at least.

The only thing I’m fairly sure about is that effectively honing or stropping a stainless-steel blade will probably require some sort of abrasive.  But … if I abrade away enough of the razor edge, the blade will no longer function (see prior post).

So it’s possible that this has been a fool’s errand.  Or it’s possible that I don’t have a good grasp of how much damage can and cannot be repaired by honing or stropping a stainless-steel razor blade.

Here’s a sequence of photographs, starting with a beaten-up blade, and ending with a blade that was honed using Brasso, an abrasive metal cleaner.

1: Original condition, note the nicks in the leading edge of the blade

2: After honing in a large-diameter piece of borosilicate glass.  This was a PYREX measuring cup, and best guess, that’s about the diameter that antique glass hones would have matched.  I’m not really seeing a whole lot of change in the nicks.

3: Hone on medium-diameter borosilicate.  I’m certain this was smaller diameter than implied by antique glass razor blade hones.  I’m still seeing no marked improvement in the nicks.

4:  Hone on very mall diameter borosilicate.  Maybe some of the nicks look a bit less sharp.  Maybe that’s my imagination.

5:  Leather strop, dry, 20 strokes of the razor, on 6″ strop.  The surface is nicely polished, but the edge is still a mess.

6:  Extensive honing using Brasso on medium- and small-diameter borosilicate.  The abrasives in the Brasso were evident (it felt gritty to move the blade against the glass), and maybe this smoothed down the nicks in the leading edge of the blade.

Here’s my take on all of that.

Rubbing these blades across any of the tested surfaces, without abrasives, didn’t seem to do much.  Plausibly, there’s something happening to the absolute edge of the blade.  But in terms of smoothing out those (almost microscopic) nicks in the blade, it was no go.  I think that’s consistent with expert advice to use abrasives when honing a stainless straight-razor.

Honing with abrasive Brasso on curved glass maybe did something, maybe not.  Definitely maybe kinda smoothed over some edges on the nicks in the blade.

But, at the end of the day, if you compare the rough, pitted edge in the first couple of photos, to the edge in the last photo, I’m not sure I’ve done much.

Conclusion.

For now, I’m stumped.

First, it’s possible that I simply don’t understand what honing or stropping is capable of doing to the edge of the blade.   Maybe a blade like the one above is beyond help.  In which case, I’m not sure what honing or stropping is going to do for me, for a stainless blade.  Because if the blade is in much better shape than that, chances are it shaves fine.

Second, no wet-shaving experts try to hone stainless blades.  It’s obvious, from reading well-informed discussion on wet shaving forums such as Badger and Blade, that wet-shaving afficianados will, occasionally, strop old-fashioned carbon steel razor blades.  But nobody strops stainless razor blades.  To the contrary, every mention of stainless and stropping/honing boils down to “they last longer, but you can’t strop them back into shape, the way you can with a carbon-steel blade”.  So, not even die-hard wet shaving fans mention any way to strop stainless razor blades.

Third, I already noted that stropping died out when stainless steel took over the blade market.  I am certainly that traditional stropping methods should not work (or work well, or work easily) on stainless, owing at least to the greater hardness of the steel.  Even straight razors — where stainless steel razors can be stropped — require use of an abrasive.  That tells me that traditional materials used to strop carbon steel just won’t cut it.

I’m really left with just two more things I can try.

First, I can add abrasives to the leather strop.  Plausibly, the combination of abrasives and the pliable backing will carry those abrasives into the nicks in the blade and scour them out.

The drawback to that is that the only way I have to strop a blade is to run it over the leather strop while it’s in my razor.  (Even that’s not ideal — I’m pretty sure the razor blade does not sit at the correct angle when I do that.)  In any case, I don’t want to subject my razor to the abrasives in Brasso or similar.  So I need to buy or rig up something to hold the blade, if I do that.

Second, I can buy one of those mystery devices that claims to extend the life of razor blade cartridges.  (reference, reference). Those work by stropping the stainless-steel blades contained in the razor cartridges.  Some people swear they work.  Others say they don’t.  The real question is whether I want to spend $10 on something that I’m betting is a scam.

When all is said and done, if I get motivated, I’ll try one more thing.  I’ll buy or make a device to hold the razor blade at the correct angle, and try stropping with a leather strop and the proper abrasives.

At that point, if that doesn’t do it, then I’m done.  I’ll judge that stropping or honing a stainless-steel razor blade is a fool’s errand.

Post 1690: Strop-a-palooza, part II. Sharpening doesn’t work.

Bottom line:  Sure, you can sharpen a safety-razor blade.  But it’ll no longer shave.  A modern safety razor only works when the blade edge is in exactly the right place.  If you remove even a tiny amount of metal from that razor edge, the blade edge will be recessed too far into the razor.  It will no longer cut hair well, no matter how sharp it is.

Recap

I started shaving with a safety razor in October 2012.  (I just looked up the purchase date on Amazon).  At that time, I bought a couple of “blade samplers” then settled on a 100-count box of Personna blades.

A little over a decade later, and it’s getting close to the time to buy some more blades.  So I started looking into the market for razor blades, and, by reference, for ways to extend the life of razor blades and disposable razors.

I’ve learned a lot.

Surely the most important thing I learned is that using shaving cream (rather than bar soap) radically extends the life of razor blades.  I no longer question people who report being able to use a single high-end disposable cartridge for an extended period of time.  Combine a high-fat shaving cream, quality stainless steel, and multiple blades in a cartridge, and it’s entirely plausible that some individuals can routinely use a single shaving cartridge for a month or more.

Arguably the next most important thing I’ve learned is that the level of “innovation” in disposable razor cartridges is, in fact, just as absurd as it looks.  For example, Dorco recently produced a seven-blade shaving cartridge. The increasing complexity and cost of shaving cartridges isn’t driven by a need to protect your face.  It’s driven by a need to protect profits via patents.  And since patents are only good for 20 years, manufacturers must come up with something (anything) new-and-different, so that they can compete in the economic “game of razors-and-blades”.

By contrast, the market for old-school double-edged razor blades is straight-up honestly competitive.  Every blade fits every razor, so there’s no way to lock you into a specific product.  Dozens of manufacturers compete for your dollars.  And as a result, at ten cents a blade, you have your pick of good options.  As a result, razor blades are almost unbelievable cheap, compared to what they cost at the dawn of the disposable blade.

The third thing I’ve learned is that a lot of what passes for wisdom in the “wet shaving” world is folklore.  Some of it’s true, some of it’s nonsense.  Everybody repeats it.  Nobody bothers to test it.  Except me, and the occasional kindred soul.

In particular, stainless steel razor blades have been sold in the U.S. since before WWII.  (And prior to that, non-rusting chromium steel blades were sold).  These days, you are hard-pressed to buy blades that aren’t made out of stainless.  Unlike old-style carbon steel blades, stainless doesn’t rust, so there’s no need to dry them off after use.  That should have been common knowledge since 1940, when the Sears catalog just flat-out said that a benefit of stainless blades is that you don’t need to wipe them off.  I proved that drying stainless blades does nothing, via experiment, earlier in this series of posts.  And yet, more-or-less every wet shaving site or blog you visit will tell you that you must carefully dry off your blades after use, otherwise it shortens the life of the blade.  Which, to be perfectly clear, is wrong for the 99% of modern blades that are made out of stainless steel.  And almost certainly is a holdover from the pre-1960s era when carbon-steel blades were still common.

Edit:  Nope.  See Post #1699.  I continued testing, and determined that you do need to dry your stainless-steel blades.  But the issue isn’t rust/corrosion (for stainless-steel blades), it’s water spots.  It’s due to calcium carbonate deposits from hard water.  A typical “water spot” is an order-of-magnitude thicker than the edge of a razor blade, and if you let water spots form on your blade, you end up with a dull blade.  If you live in an area with hard water, you do in fact need to dry off your blade.  Even your stainless-steel blade.

So, before I actually get around to stropping some blades, I want to ask and answer a series of questions.  These may seem obvious to you, but not to me.  If you just want to get to my first attempt at literally sharpening a stainless razor blade, skip down — the title of that section is in red

Definitions:  Sharpening versus honing versus stropping.

I am not a knife fanatic, so let me offer you my amateur understanding of the distinction between sharpening, honing, and stropping.  It boils down to how much material you’re trying to remove.  Sharpening typically uses a relatively coarse abrasive and can remove considerable amounts of metal in order to form an edge.  Honing uses much finer abrasives, removes little metal, and is more of a way to polish up an already-formed sharp edge.  Stropping ideally removes no metal, and either uses no abrasives or very fine abrasives to finish the job of polishing the razor edge of the blade.

The name of the process corresponds to the edge you’re trying to achieve, and where you are in getting to that edge.  You sharpen a lawn mower blade.  If you care, you might hone an ax after you sharpen it, to get the longest life before re-sharpening is required.  If a straight razor is in sad shape, you’d sharpen, hone, and strop it to restore the razor edge.

In the past, when the only option for blade sharpening was scraping a blade across flat stones of various sorts, that could sort-of be correlated with the motions used.  You typically sharpen an edge by moving it across the stone in the direction of cutting.  You hone an edge by moving it with approximately circular strokes and very light pressure.  You strop an edge by moving it backwards — opposite the direction of cutting — over the strop.

So, can I strop a stainless-steel razor blade?

The last thing I need to do, to finish this deep dive into understanding wet shaving, is to learn how to strop a razor blade.  In particular, how to strop a stainless-steel razor blade.  Correctly.  So that it actually sharpens the blade.

Well, yes, I can, in fact, strop a stainless-steel razor blade.  I already did that, earlier in this series (Post #1673).  Put a stainless blade in your razor, run it backward (opposite the direction of shaving) over a piece of leather, a few times, keeping a fairly steady pressure on the razor.  And you’ve just stropped the blade.  Flip and repeat.

I can do it, but does it do any good?  The results of my first attempt were mediocre.  Stropping a blade that way definitely brightened the razor edge, and seemed to remove a lot of irregularities.  But it didn’t seem to sharpen that stainless blade, and it didn’t make seem to make it shave any better.

Here’s the big if:  I’m not sure it can be done effectively.  Or, at least, not by the average user.  In my review of the history of the safety-razor market, I noted that the rise of stainless steel blades coincided with the decline in re-sharpening blades via stropping.  Early on, it was assumed that the disposable-blade user would strop those blades to maintain a keen edge.  Numerous and varied devices were sold to accomplish that task.  But those were, by and large, carbon-steel blades, which aren’t as hard as stainless.  The practice of stropping razor blades peaked in the 1930s.  And as blades got cheaper, and stainless steel took over the market, the practice of routinely stropping razor blades disappeared.

Near as I can tell, nobody offers any device currently for stropping an individual razor blade.  There are a handful of devices for stropping shaving cartridges, but I would describe them as “fringe” devices.  (Here’s a couple of examples on Amazon (reference, reference)).  They say “razor blade” when they actually mean “razor cartridge”.  And among the reasons I think of them as “fringe” devices is that their description of what stropping does (cleans, removes oxidation) is a poor match for how blade experts describe the effects of stropping (straightening, re-forming, and polishing the razor edge.)

I am absolutely sure you can strop a stainless-steel straight razor.  Experts do that all the time.  So there’s nothing about the metal, per se, that prevents stropping.  (Although the expert consensus is that a plain-leather strop is inadequate and that abrasive “compound” should be used when stropping stainless).

What I’m not sure is whether I can strop (or hone) an itty-bitty flexible stainless steel razor blade.  In some fashion that’s convenient enough that I’d be willing to do it in a routine basis.  So the problem here isn’t really one of the science.  It’s really about the engineering.

 

Question 1:  Why do they say that you can’t sharpen a double-edged razor blade?

Recall the difference between sharpen, hone, and strop, as defined above.

Even though I am not a knife fanatic, I know that “you can’t sharpen a double-edged razor blade” has to be bullshit.  You can sharpen any type of hard metal.  So of course you can sharpen a razor blade.  I could, if I chose to, pull a thoroughly dull razor blade through my kitchen knife sharpener.  And I bet it would come out sharper.

And yet, you will see this repeated as an absolutely unquestionable fact.  Everybody knows you can’t sharpen a razor blade.  It took me two weeks of playing with razors and blades before it finally dawned on me what they actually mean.  Of course you can sharpen a razor blade. But in theory, sharpening a razor blade makes it useless.

Why?  Sharpening it — removing enough material to form a new edge — would make it slightly smaller.  (And, likely, non-uniform in width.)  And a slightly smaller blade won’t work, no matter how sharp it is.

This is the end of my razor, under a microscope.  It is manufactured so that the razor blade, when clamped into a curved shape, aligns perfectly with the upper and lower edges of the razor.  That’s what puts the “safety” in this type of safety razor.  (Separately, the blade also arrives at a precisely-determined angle).  I have no way to measure how far the edge of the blade sticks out, but by eye, it’s in tenth-of-a-millimeter territory.

Bottom line:  Sure I can sharpen that.  And if I manage to scrape 0.1 mm off the edge, the blade will cease to function.  Which, given how thin the metal is, and how ham-handed I am with a sharpening stone, is pretty much a given.  So, no.  In all likelihood, I can’t sharpen a razor blade and continue to use it for shaving.

As a byproduct, I now understand that there’s an ultimate, impassable limit on razor blade re-use.  You will eventually wear them down far enough that they will cease to function.  They won’t stick out of the razor far enough to cut your hair.  No matter what miracle-of-restoration you manage to use, you can’t re-use one of these forever.

Test 1:  Run a stainless-steel razor blade through a common kitchen knife sharpener.

Might as well start the practical portion of this by running a used blade through a kitchen knife sharpener.  It’s the least-effort approach.  The questions are, does that sharpen the blade, and is the blade unusable afterwards.

Now, to be clear, this is not a smart thing to do.  If nothing else, the sharpener will be set at too wide an angle, because it’s designed for the edged of knives, not the edges of razors.  But let’s proceed and see what happens.

In this case, I’m starting with the ceramic (fine) portion of this $4 knife sharpener.  (Which, I will add, works just fine for keeping my stainless-steel kitchen knives sharp.)  The ceramic is marked as “sharpening”, but there’s some chance that it merely acts as a hone.  I can’t find a definitive answer on that.

Source:  Amazon

I marked a badly chipped section of the blade edge, attached a couple of magnets to the blade to form a little handle, then ran that through the ceramic (fine) side.   Twenty-four fairly heavy-handed passes through the ceramic (fine) sharpener, and while that chip might be a little more rounded, it’s just about as deep as when I started.  That blade edge is so rough that I can actually feel the divots as I run it through the sharpener.

OK, let me try 12 heavy-handed passes through the coarse (carbide) side.  For perspective, that’s vastly more passes than I use to dress up even a dull kitchen stainless-steel knife.  Normally, I don’t even need to touch the coarse side of the sharpener.  At the extreme, I might use five passes coarse and fine to dress the edge of a knife before (say) carving meat.

That finally reduces the nick to the point where I can’t feel it when sharpening.  But note that what I’ve done is more-or-less remove the entire second facet of the blade edge.  The nick is in the same place.  The blade is now ever-so-slightly narrower.

That said, I just tried shaving with it, and I have not narrowed it so much that it doesn’t shave at all.  It will still shave, a bit.  But it does exactly what you would expect.  By moving that edge back, it now leaves stubble.  That’s rather subjective, comparing one side of my face shaved with the sharpened edge, and one side shaved with the other edge of the same blade.  It’s a very worn blade, and neither edge gives a good shave.  But if I had to call it, yep, removing that minuscule amount of steel from the edge makes the blade forever unusable for getting a close shave.

So, I can sharpen it.  I did sharpen it.  It just won’t shave worth a damn after I did that. No matter how sharp it is.  Because it’s now too narrow.

If nothing else, I’ve learned that stainless steel razor blades seem to be extremely hard.  For sure, I don’t have to worry about accidentally sharpening them to the point where they are too narrow to function.  I really had to work at it do do that.

And I think I’ve confirmed that it’s useless to try to sharpen a razor blade.  In the technical sense of removing a significant amount of material in order to produce a more uniform blade edge.  Narrowing that razor blade by an amount that is not even visible to the naked eye was enough to render it forever worthless for use in a safety razor.

Finally, I’ll note that because I’m using a kitchen knife sharpener, I’m not sharpening the entire surface of the bevel.  The bevel of a razor blade is cut to a much narrower angle than the bevel of a typical kitchen knife.  Basically, I’m just sharpening the very tip of the razor edge.  So it’s not a huge surprise that this did little more than erode the edge.  The interesting part is how little it takes to render the blade useless.

Addendum: Are all stainless razor blades sharpened the same way initially?

Oddly enough, the answer is no.  Manufactures put a variety of different edges on their stainless steel razor blades.

The blades that I’ve been putting under a microscope so far — Personnna — were clearly ground at two different angles to form the razor edge.  It’s what I’ve termed a “faceted” edge.  That seems like a lot of effort for a 10-cent disposable item.  But it is what it is.

I’m pretty sure I’m going to erase that if I strop that blade enough.  Does that matter?  I wonder whether that’s standard practice in the industry?

Below you can see that there is no one industry standard for the final sharpening of a stainless-steel razor blade.  You’ve got everything from a simple flat edge, to a faceted (two-angle) edge, to a hollow-ground edge.

I looked at the edges from a random collection of blade brands that I happened to have on hand.  Here’s what I think the edge grinding is, based on looking at them under a crude microscope.

  • Faceted (two-angle edge):  Personna, Voshkod, Shark (I think)  Note the clear, distinct line adjacent to the extreme edge of the blade.

  • Flat-ground:  Astra, Gillette, Feather.  No line.

  • Hollow-ground:  Tiger.  You can’t see this in the still photo, but by moving the light source, it was clear that the edge was hollow-ground.

The extra effort in grinding the edge seems to have nothing to do with the quality of the blade.  Of these, Feather is almost certainly recognized as the highest-end blade offered, and Feather has a simple flat-ground edge.

In any case, as I proceed, I’m not going to worry about destroying the faceted edge of the blade by stropping. Plenty of razor blades cut just fine with a flat, single-cut edge.

Conclusion

  • Stainless steel razor blades appear to be made of extremely hard metal. It took a lot more passes to make a dent in a razor blade than it does to sharpen my stainless steel kitchen knives.  (Alternatively, some say that stainless is not hard, but has extremely good wear resistance.  I don’t much care what the technically correct explanation is.  Either way, it’s a lot harder to sharpen stainless than it is to sharpen carbon steel.)
  • Removing even tiny amounts of metal from the edge ruins the blade.
  • Manufacturers grind those final edges in all sorts of ways:  straight, facet, hollow-ground.

At the end of the day, the key practical question is whether the decline in the practice of stropping razor blades was driven by economics or technology? Did people stop doing that because blades got cheap?  Or did people stop doing that because blades started to be made out of much harder material, as the market switched from carbon steel to stainless steel.

At this point, I think I’m leaning toward technology.  As of right now, given how hard those blades appear to be, and given that stropping stainless straight razors requires abrasives, it sure looks like it’s going to be difficult or impossible to strop a dull stainless razor blade back to sharpness using any sort of common materials.

Basically, the tricks that might have worked on your grandfather’s carbon-steel blades just ain’t gonna cut it for stainless.  And I’m not at all sure what will.  I’ll give it a try in my next post.