Category: Making

Projects that make or build something.

Post #807: A vastly simpler mask liner using Filtrete ™

Source for base data: 3M, ASHRAE.  See Post #593 for writeup of these and other filtration standards.

I’ve done several posts about making masks out of Filtrete ™ home air-filter material.  Each time I return to that task, I find simpler ways to work with Filtrete ™.

In this post, I’m going to show just how easy it is to take a Filtrete ™ home air filter and make some simple, flat, easy-to-handle, fiber-free pieces for use inside cloth masks.  In a nutshell, extract the Filtrete ™ fabric from the air filter and hot-glue it between two layers of the thinnest synthetic fabric you can find.

Then end-user can then cut it to size, for use as a liner for a cloth mask.  That seems to work just fine, and nothing more labor-intensive is needed.  The materials run well under $0.25 per mask liner, depending on what size filter you buy, and how large you cut your mask liners.

A few tips and tricks for doing that are given below.  Of which, the only one that might not occur to you is to use kitchen “parchment paper” as a non-stick surface as you are gluing.

Continue reading Post #807: A vastly simpler mask liner using Filtrete ™

Post #790: Cigarette smoke does not work as a test for mask filtration ability

Way back in Post #750, 7/9/2020, I had the notion to use cigarette smoke to test the ability of masks to filter out aerosol-sized particles.  There is a need for some sort of home test, because it’s next-to-impossible to tell how well or poorly any off-the-shelf mask works.  That’s particularly true for the “KN95” masks now being sold in everywhere (Post #747).

The theory seemed sound.  Cigarette smoke particles are about the right size, and in the past, some people did in fact use N95 masks to try to avoid second-hand smoke.

Now, having executed this test on my back porch this afternoon, I can attest that it doesn’t work at all. I can smell cigarette smoke strongly right through a genuine (but quite old) 3M N95 respirator (upper left, above).  And I could not tell that the smell of smoke was any stronger when I used a worn-out 3M N95 dust mask (next), or a dust/surgical mask (blue) with no aerosol filtration capability. Continue reading Post #790: Cigarette smoke does not work as a test for mask filtration ability

Post #780: Making an aerosol-filtering respirator from a dust mask and Filtrete (r) 1900

This post shows one way to upgrade a common dust mask so that it filters aerosol-sized particles.  The basic idea is not exactly rocket science:  Cover it with something that filters aerosol-sized particles. Continue reading Post #780: Making an aerosol-filtering respirator from a dust mask and Filtrete (r) 1900

Post #G14: Garden update

Source:  My garden.

If you have no interest in gardening, skip this.

Squash Vine Borer.  Looks like the SVB season is over.  I spend a lot of time walking around my garden, and my last sighting was 7/25/2020.  My first was 7/5/2020, making the SVB season just about exactly three weeks long.

My spraying regimen — I would term it spinosad with a side order of neem — appears to have worked so far.  In the sense that none of my many cucurbits is showing symptoms of SVB infestation.  Yet.  So that’s 0.008% spinosad solution (made up from concentrate), sprayed on the stems of my cucurbits every five days or so.  In the late evening, to avoid the bees.  Plus one random spraying with 100% neem (the variant that contains the insecticides, not the “hydrophobic extract” that’s just oil), more out of paranoia than from any thought-through plan.  I’ll have to keep up the spray for another week or so to account for the lag between egg-laying and hatch-out.

Powdery mildew.  I have that on nearly all my cucurbits now.  I should have been taking preventive measures, but I didn’t, so now I’m playing catch-up.

I tried baking soda (sodium bicarbonate) solution, once.  Recipe given in earlier posts.  I tried potassium bicarbonate solution, once.  Just substitute K for Na in the recipe.  If those had an effect, it was fairly subtle.

So I’m pulling out all the stops and following the hydrogen peroxide regimen as outlined on The Rusted Garden blog.  See the video above.  (Seriously, look this guy up on Youtube.  He’s in Maryland.  If you’re not envious of his garden, you’re a far better gardener than I am.)

This involves pruning out any leaves that are badly hit with powdery mildew, then spraying daily with a dilute solution of hydrogen peroxide.  (Around) 4 to 6 ounces of 3% hydrogen peroxide per gallon of water.)

If nothing else, this is certainly cheap.  A quart of 3% H2O2 is $1.29 at the grocery store, and is enough to treat my entire garden four times.  I’ll post in a few days and report back the results.

Ongoing, I’m also pruning my squash and pumpkin plants.  It never even occurred to me to do that.  (I’m kind of a laissez-faire gardener, which is another way of saying, I do as little as possible.)   But after listening the the logic behind it and seeing the results on The Rusted Garden, I’m all in.  As with the mildew issue, I’m running behind, so this will be an ongoing process.

I’m planting mid-season replacements for some of my cucumbers.  That’s another thing I’ve never done before.  To me, you plant in the spring, you harvest in the fall.  But apparently that’s not what smart gardeners do.  In this case, my Spacemaster 80 cucumbers were incredibly productive, until the simultaneous effects of bacterial wilt and powdery mildew got hold of them.  They are now such a mess that I’m pulling them out and replanting.  Apparently, with warm soil and a bit of fertilizer, there’s plenty of time to have them grow up and produce cucumbers before first frost.

Cucumber beetles and bacterial wilt.  Today I was 4/4 (attempts/kills) when inspecting my squash and pumpkin blossoms, long-nosed pliers in hand.  (As described in Post #G13).  I think that I have seen no new cases of bacterial wilt these past few days, but it’s hard to say, as it takes some time for the plant to die off.  In any case, I’ve gone from finding dozens in one pass through the blossoms, to consistently finding maybe four or five.  Tentatively, I think I’m winning.

Timing is fairly key to this operation.  The limiting factor is grumpy bumblebees.  If I get out there at 7 AM, there are bumblebees  just kind of sitting in the squash blossoms, zoned out.  My wife swears that bumblebees sleep in squash blossoms.  (Aww!)  I, by contrast, thought that was way too cute to be real.  A quick google search shows that she’s correct.  Not only do they sleep in flowers, but squash blossoms are preferred due to size and configuration, and squash blossoms provide considerable protection from the cold.  Snug as a bee in a blossom, no joke.  The upshot is that I have to wait for them to get up and go to work before I can patrol for cucumber beetles.

Tomato ripening is now occurring generally across my tomato plants.  Slowly.  My cherry tomatoes are ripening a few at a time, and some Rutgers tomatoes are finally turning pink.  Still going slowly, though, that’s for sure.

And the deer have not yet returned. As evidenced by the fact that I still have standing sunflowers, above.  On net, I’m crediting Bobbex deer repellent.  It really stinks!  I think the motion-activated radio comes in a close second (Post #G07).  I don’t know if it scares the deer, but it sure manages to scare the pee out of me every time I inadvertently trigger it.

Post #G13: Garden update

Not everything in my garden is a problem.  I just tend to talk about the issues that I’m trying to solve.  I’m attempting to achieve some balance here.  Topic below, in order, are:

  • Deer (success),
  • Birds (limited success),
  • Cucumber Beetles (apparent success);
  • Squash vine borer (possible success, possibly too soon to tell),
  • Powdery mildew (no success at all, yet, but I’ve learned to prune my squash).

Continue reading Post #G13: Garden update

Post #747: Can Kents clarify KN95 chaos? Updated

Source:  Depositphotos.com

Update 2:  This didn’t work, at all.  Not even a little bit.  See Post #790 for details.  You can’t use the odor of cigarette smoke to test mask filtration.

Update:  See postscript at bottom.  The ability of genuine N95 masks to filter smoke particles is well known and well documented.  In that light, my proposed “sniff test” for KN95 masks looks fairly promising.  To the extent that a mask reduces the odor of cigarette smoke, then it is filtering out virus-sized particles.

In Post #740, I noted that my local convenience store had “KN95” masks for sale.    I’ve heard a rumor that one of the local hardware stores is also selling such masks.  (I plan to check that out soon.)  And I exchanged emails with  neighbor who is in the process of purchasing some KN95s, from a couple of different sources, for daily wear at work.

In theory, wearing a KN95 gives you the same protection as an N95 respirator.  So, in theory, upgrading from a cloth mask or similar to a KN95 is a smart thing to do.

In practice, not so fast.  I’ve started looking into the “KN95” mask market, and it is complete chaos.  I guess that’s no surprise.  That’s more-or-less of a piece with the entire Federal response to COVID-19. Continue reading Post #747: Can Kents clarify KN95 chaos? Updated

Post #G07: With my luck, the local deer are all Garth Brooks fans.

Source:  Clipart-library.com

This is one of my occasional posts on gardening.  In it, I’m going to explain how to take an off-the-shelf plug-and-play motion sensor and turn it into flexible device for deterring deer.

As anyone who gardens in this area will tell you, deer are pests.  Cute as all get-out.  But pests, nevertheless.  And, unfortunately, either they can’t read, or they just don’t obey signs.  So unless you want to feed the local deer, either you erect some serious fencing around your garden, or you do something else to convince your local deer to feed elsewhere.

What I describe in this post is one of several deer-deterrence measures I have taken.  They seem to be working so far.  But I haven’t seen any elephants in my yard recently, either, and that doesn’t mean I’ve found a good elephant repellent.

Background

 

Source:  USDA

At the end of March, I decided to put in a big vegetable garden.  Just to have something to do during the pandemic (Post #580).

I recycled my “MAC” signs into raised beds.  Figuring, if there was no longer a MAC ordinance, I’d have to get signs reprinted anyway (Post #G05).  And that’s how things did shake out, this past month (Post #706).

 

Above, that’s the same garden, today.  Note the complete and total absence of deer!  The red arrow points to my latest deer deterrent.  That’s a trash bag covering up an indoor motion detector.  That’s what I explain next.

Making a flexible deer scarer.

There are some things that absolutely will keep deer out of your garden.  A tall and sturdy fence.  A shorter fence, if you can plant enough shrubbery around it to prevent the deer from jumping it.  A two-layer electric fence.

I didn’t want to do any of those and/or they were illegal and/or my wife didn’t want that in the back yard.  Not that I can blame her.  Nor was I willing to buy a few hundred dollars in supplies, and put in hours of labor, to produce a few tens of dollars of vegetables.

Any cheap and easy deer deterrents are likely to be, at best, partially effective.  I’m not going to run through all the commercial and home-made deer deterrents, except to say that a) there is little agreement on effectiveness of most of them, and b) the conventional wisdom is that deer will get used to just about any un-changing device designed to scare them.

I had several deer deterrents in use, and they seem to be mostly effective.  This includes Bobbex deer repellent, a Yard Enforcer motion-activated sprayer, some older ultrasonic “pest scarers” that seem to be useless and/or broken.  Liberal use of blood meal throughout the garden.  And, of course, the classic of low-end DIY deer repellents — bars of Irish Spring soap. (Manly, yes, but deer hate it too.)

I decided to add a motion-activated noise/motion device of some sort.  Just something to startle the deer as they chow down on my string beans.  But didn’t really find what I was looking for as a commercial product.  So I decided to make one.

My first attempt failed.  I tried to make one out of a cheap motion-activated floodlight.  Figured that, in place of the floodlights, I’d just put in some screw-in sockets, and then plug something into that.  But modern motion-activated floodlights are all (or nearly all) designed to turn off during the day.  Basically, a) they don’t work in daylight, b) everything that I tried to block the daylight also messed up the infrared-based motion sensor, and c) I ended up ruining the unit when I tried to drill out the wired-in cheap light sensor (literally, just an LED).

Not only did I not figure out how to defeat the nighttime-use-only problem, those require a lot of additional parts, and they require having an electrical box.  And the cheap one I got from Home Depot was clearly going to require a lot of sealant in order to be weatherproof.  And, owing to the electronics of the motion sensor, there are limits on what sort of electrical/electronic device you can control with that.  All in all, too complicated and too clever by half.  But designed for outdoor use.

Here’s what saved the day.

Source:  Amazon.com

My second attempt worked perfectly:  I used an off-the-shelf plug-and-play indoor motion sensor.  What you see above is an indoor motion sensor with a roughly 25-foot range.  It has no problem working in daylight.

As importantly, this device has no problem “seeing” right through a thin plastic bag.  So all you need to do, to use this outside, is set up whatever you are going to set up.  Then put a white garbage bag over it, to keep the rain off the electronics.

What’s more, it’s electrically bulletproof.  Some light controls used electronics to turn the lights on and off, and so have significant limitations at to the type of device they can control.  (E.g., some on-at-dusk, off-at-dawn controllers can’t deal with compact fluorescent bulbs).  But this device uses a physical relay to turn the electricity on and off (you can hear it click).  That means there are no restrictions (other than total wattage) as to the type of electronics it can control.  And it can handle up to 1200 watts.  That means you can use a wide range of household devices as noise-makers.  For example, I could plug my Shop-Vac into this.

With this part in hand and tested, the rest of the deer-scaring device is straightforward.  Put a stake in the ground where you want to use this.  Run an outdoor extension cord out to your garden, plug this in, mount it to that stake.  Plug the device of your choice into this.  (Or use a multiple tap, and plug in several devices).

Then cover the whole assembly with a white plastic trash bag. When a deer walks by, it will now trigger whatever device you have plugged in.  For the amount of time you choose.

For my first round, I’m following a recommendation I’ve seen in several places, and have hooked this up to a radio.  Then I put the radio in a small metal garbage can.  That keeps the water off the radio.  I have it set, very loud, to WMZQ.  Now when a deer tries to walk up to my beans, it is greeted with one minute of loud country music.  Which then stops.  And if they are still there, it runs for another minute.  And so on.

It’s far enough into the yard that I don’t think I’ve created a neighbor-annoyance device.  But if you’re standing right next to it, the effect is pretty startling.

The nice thing is, if the deer get used to this, I can just change out the radio for something else.  Maybe a weed whacker next time?  And there are all kinds of sound-and-motion possibilities using a Shop-Vac exhaust.  Maybe some flashing lights.  Plug in a three-way tap and operate three devices, subject to the 1200 watt limit.

Basically, anything you can plug into a standard wall outlet, and that doesn’t draw too much current, can serve in place of the radio.  Which means you can keep it fresh, for your deer.  And keep them from getting used to this deer deterrent.

 

Post #648: Instructions for making a Filtrete™ mask liner

EDIT:  See Post #807 for a vastly simpler approach to making a mask liner for a typical cloth mask.  Even if you decide to pleat it (as below), the methods in that later post are much easier than what I show below.

EDIT:  By contrast, If you want to make a stand-alone Filtrete mask (not a mask liner) See Post #780 for a better way of creating a high-quality aerosol-filtering mask.  What you see below is an OK retrofit for existing cloth masks.  But if you can find a mask that makes a good seal against your face (e.g., a 3M dust mask),  you’d be better off following the instructions in Post #780 and upgrading that tight-fitting mask so that it filters aerosols.

To see all posts on masks, use the drop-down search menu and pick “masks” as the category.

The white object above is what you are going to make.  The blue “single-use” disposable mask is there to show the size, and to clue you in that the you’re going to make a piece of Filtrete™ into something resembling the body of a pleated surgical mask.

Continue reading Post #648: Instructions for making a Filtrete™ mask liner

Post #646: Second mask liner for distribution

This white cloth above is my second and final design for a mask liner.  (The blue single-use mask is just there to show the size).

This is a piece of Filtrete 2500, encapsulated between two sheets of thin spun-bonded polyester cloth (a.k.a, floating row cover) using fusible interfacing to bind the polyester layers at the edges, then stapled to form a pleated sheet in roughly the same format as a standard surgical mask.

The idea is that you would wear this inside your tight-fitting cloth mask.  I am leaving a generous allowance of excess polyester cloth so that you can trim the edges to get the best fit to your own mask.  And so that you can find an expedient way to attach this to your own mask, in the correct position, without poking a hole in the Filtrete material.

There is no nosepiece on these.  If your cloth mask does not have a nosepiece, you should make one for it.  There are instructions for that all over the internet. You will want to position this so that the top edge of the Filtrete material is located under the metal portion of your mask nosepiece.

The pleasant surprise here is that, as constructed, this is incredibly breathable.  You pretty much don’t notice that it’s there.  (Which is, in fact, what 3M advertises about their filters.  They trap 0.3 micron particles without adding materially to the back-pressure in an HVAC system.  The MERV-13 material I have obtained, by contrast, seems to have a lot more back pressure.  So I’m going with Filtrete until I run out of it, if that ever happens.)

If , upon examination of one of these, you have any fears about inhaling a stray fiber, please attach you own thin cloth backing to the whole assembly.  This is just three pieces of non-woven polyester (or possibly polypropylene fiber).  But if the idea of breathing though this bothers you, modify it, or don’t ask for one.

If you have a mask with a filter pocket, pick out the staples and you will have a 6.75″ x 6.5″ piece of Filtrete 2500, encapsulated in spun-bonded polyester.  As long as a piece that size will do you, I don’t even have to offer something for those of you with filter pockets in your cloth masks.  Just undo the staples.

In fact, if I see little enough demand, I’ll use two pieces of Filtrete (r).  That should, in theory, capture 95% of 0.3 micron particles.  And as I said, it’s amazingly breathable, so that there seems little danger that you will breath around this, rather than through this, if you use it in a filter pocket.

For now, I’m going to advise you not to wash this material.  I know that washing N95 masks compromises there filtration ability somewhat.  I have no clue what washing does to Filtrete.  Do what hospital workers are now doing to re-use N95 masks. Drop this is a paper bag and leave it alone for a few days.  Virus particles that you may have picked up with self-destruct over time.

I need to tweak some details.  I’ll probably make this a little less wide than my single-use masks (6.75″), because I don’t want my pleats to compromise the fit of your mask.  I may also rethink the size of the pleats. But this the general idea.

The construction of these is still slow and fussy, but I’m betting I can get better at this as time moves on.  But right now, I have zero stock, and it’s going to be a while before I have a considerable supply of either of these mask liners.

If you have a mask with a tight-fitting nosepiece, this is a better option than my first mask liner.  In fact, I’m only going to offer the first one with a nosepiece, and strongly encourage people to use this design instead.  It uses less material, and it doesn’t have the cheap commercial mask material impeding the breathability of it, so, plausibly, with this design, more of your breath goes through the cloth, not around it.

In short, it’s a better design.  And, if for whatever reason, the way I’ve pleated this does not work for you, you can pick out the staples, redo it, and re-staple it.  You could probably even just tape your pleats in place.

I make no guarantees as to the effectiveness of this mask liner, if any.  I will only state that I have in fact made this out of the materials that I say I have made this from.  Most importantly, if this in any way compromises the fit of your own cloth mask, do not use it.  Minimizing air leaks is by far the most important aspect of mask use.  Better that your cloth mask filters most of your air, however it does, than that this mask liner gives you filtration that you don’t use, because it disturbs the fit of your mask.

I’m probably going to do one more variant on this that merely shapes the material into a rough conical mask, and does not have the pleats.  That would have lower risk of disturbing your cloth mask fit.  But that’s another level of difficulty.  And, frankly, I hope I am too busy making these first two designs to have the time to come up with a third.

I’m now going going to make the following offers, on some commercial platform (likely Google Forms, maybe SurveyMonkey).  I’ll set that up today and post the link here.  My offers, to Town of Vienna residents and small businesses, are the following.  You may ask for:

  • A few single-use masks, just like the blue mask in the picture above.  Trust me, when I call those cheap, it’s an insult to the word cheap.  The nosepiece, as-is, is completely inadequate, and if you use these for any purpose as stand-alone masks, you should tape a piece of wire over the embedded nosepiece and use that to shape the mask to your face.
  • A few of the white mask liner pictured above.  Unless I get feedback calling for other sizes, I’m only making one size.  It’s not difficult to make those in any size.  If you just want a piece of Filtrete, in any easy-to-handle form, for the filter pocket of your mask, order some of these.
  • A few of my first design, with nosepiece, but only for individuals who do not have a cloth mask with an adequate nosepiece.   E.g., if the only thing you’ve got is a bandana, order that one, and wear your bandana over it.
  • If I fall behind, I’ll start offering these as kits.  I’ll give you the parts, you do the pleating and the stapling.

If you don’t want to take some for free, please donate some money to some Vienna-oriented charity.  My best guess is that (e.g.) the economic situation for local small business is not going to improve any time soon.

I’ll have an order form up as soon as I can figure out how.  I’m not going to put it on this website because I realize that lot of people don’t much like what I’ve had to say, and I don’t your dislike of me to stop you from asking for one of these.  And if you know any Vienna business that still have public-facing employees (i.e., not delivery people, but anybody who has to talk to customers in person), consider pointing them to this order form.  When I figure out how to do it.

Again, I make no claims or warranties as to effectiveness.  Use at your own risk.

Christopher Hogan, Ph.D.  chogan@directresearch.com

Post #644: First mask liner for distribution

This is the first model of “mask liner” that I am offering to anyone in the Town of Vienna who would like them. I will go learn Google Forms tonight and set up a form for requesting these, tomorrow.

The base of the mask liner is cheap commercially-made “single-use” mask, not suitable for use by hospital workers.  That’s the blue mask pictured above.  I then pleat a piece of Filtrete (plus thin cover cloth) and staple that over the outside of the mask.  Finally, I add a stiff full-length metal nosepiece in the form of a galvanized wire.

Here, so as not to waste the Filtrete, I used a piece of printed cloth.  The actual masks will be plain white on the outside.

My intention with making mask liners is that you would wear this under your regular cloth mask.  The small size and weak elastic makes these potentially quite “leaky”, and this really should be used with a tight-fitting cloth mask pressing this against your face.

In an emergency, you could wear this as a mask, by itself, but that’s inadvisable due to the potential for air leaks.  If you were forced to do that, you would be well advised to add a couple of pieces of string to the loops on the nosepiece, then tie those behind your head and pull this more tightly against your face.

Surgical-style masks like these are compromised by air leaks, so the nosepiece is important.  If your existing mask has a good metal nosepiece and fits snugly against the bride of your nose and cheeks, order the version of the mask liner that does not have a nosepiece.  The additional nosepiece will just be in the way.  And wear this so that this mask liner is held snugly to your face by your existing mask nosepiece.  If you have a mask that lacks a good nosepiece, then order the version of the liner that includes a nosepiece, as pictured above.

I make no warranties as to how well these work.  I make no warranties that they work at all.  You use these completely at your own risk.

The theory behind this is that it should help filter out smaller particles, of a size that cloth mask is probably unable to filter well, if at all.  In particular, Filtrete 2500 claims to catch 77% of particles down to 0.3 microns.  Two layers should, in theory capture 95% (but I have not tested that yet for breathability).

Surgical masks do not seal to the face the way respirators do.  No matter what you do with a surgical mask, short of literally taping it to your face, you will breath some unfiltered air.  And the harder it is to breathe through the mask, the more air will go around the mask.  So I have tried to keep this as breathable as possible.

These take longer to make than I had hoped.  So I’m not sure how fast I can make them. At some point, if you have a stapler, it might be more expeditious for me to mail these out as kits, rather than assembled.  All you need is a stapler, four clothespins, and (if you need the nosepiece) a few pieces of high-quality tape.  I would supply the rest.

Do not wash these masks.  Washing reduces the filtration ability of most high-quality filtering material.  You should treat these masks exactly as hospital workers now treat N95 respirators for re-use.  Wash your hands, carefully take it off your face (without touching your face), drop it in an open paper bag, and leave it for a while.   The virus self-destructs over time.  How long is a while?  If you are phobic, leave it for three days.  Otherwise, two days.  So if you plan to be out every day (which I think is bordering on crazy unless your job requires it), you’d want two of these, to use in rotation.

How long will these last?  I suspect that the elastic will break early on, but as long as you are using these under a tight-fitting cloth mask, that’s just a nuisance.  The filter material should be good for hundreds of hours of breathing, but I have to do a calculation to determine just how long it should last (based on the rated lifetime of the original filter assembly, and so on).

My intent here is that this would be used when (e.g.) on a weekly shopping trip.  Or when going to the doctor.  I don’t really see these as suitable for use on an 8-hour shift, day after day.  I don’t think they’ll last that long, owing to the generally cheap construction.

I’ll have the form up tomorrow to allow you to order this, or order a kit of materials to make these, or just order up a piece of Filtrete, if you have a cloth mask with a filter pocket in it.  Likely, I’ll ask you to pick your up off my front porch.  If you’re hesitant to take this as a gift, then donate a few dollars per mask to some worthy Vienna-centric charity.

Whether or not Filtrete will work, as advertised, in this case, is purely an act of faith.  For all the world, the stuff looks like a pleated piece of paper with some fibers on one side.  But you have to trust something.  I trust 3M.

That said, you get no guarantee from me.  It should work, but there is absolutely no way to test that, under the circumstances.

Finally, extra points for any old-timers who recognize the brand of tape measure.  Ya’ can’t hardly get those any more.