Today is the day when a whole lot of campaign signs go straight into the dumpster. Along with the political aspirations of half the recent candidates,
Which is a pity, really. (The signs, I mean.) The best of those signs are made to last a long time. We really ought to do better than treating them as a single-use disposable.
So I suggest that the first Wednesday following the first Monday in November be declared Campaign Sign Recycling Day. In keeping with that, today is a good day for me to make something useful out of some dead political yard signs.
This post is the theory. Next post is the actual assembly.
We’re talking Coroplast.
Source: Coroplast, Inc.
Campaign yard signs come in several varieties.
Cheap campaign yard signs aren’t re-usable in any obvious way. Some are coated cardboard, on some sort of stick. Some are a printed plastic sleeve that fits over a three-sided wire frame. For both of those, the metal frames (if any) can be recycled. But the signs themselves aren’t good for much. Far as I can tell, once they’ve served their purpose, they’re trash.
By contrast, high-end campaign yard signs are Coroplast(r). That is, corrugated plastic sheets — two sheets of plastic bound together with thin plastic channels. As pictured above. Effectively, they are built like corrugated cardboard, but plastic.
These sheets — typically made from polypropylene — have a surprising amount of structural integrity. Much like corrugated cardboard, they are quite resistant to bending or folding across the corrugations. This means you could use a single thickness of Coroplast to build light-duty objects, and multiple thicknesses to build heavy duty objects.
These also stand up well to being used outside. The ones forming the sides of my oldest raised beds now have more than five years of cumulative outdoor exposure (first as yard signs, then as raised bed sides.) Only this year did they begin to show brittleness from all that sunshine and weather. (And if I’d cared to keep them painted, I probably could have avoided that, as most of the damage is from exposure to the UV in sunlight.)
Fastenating
I’d say that the biggest downside is that these can’t be glued together. (Or, at least, not well, or not easily, using conventional glues). The underlying material (typically, polypropylene) just doesn’t stick to much. And the ink coating — the printed message — further complicates things.
Near as I can tell, most people who make DIY projects with Coroplast sheet opt for some sort of mechanical fastening. That can be as simple as cutting slots and tabs, so that sheets fit together. Than can include melting sheets together, in places, to form a sort of plastic rivet. Or can include using actual metal fasteners (bolts, washers, nuts) to hold the plastic parts together. Or staple or nail them into a wood backing.
(The big exception being model airplane enthusiasts, for whom gluing coroplast is the only practical option. That said, after having read one or two sites discussing that use, I’m convinced that gluing up Coroplast is not something that you’re likely to get right the first time.)
There are chemical methods that might, in theory, hold these sheets together. Some are specialized glues specifically designed for this sort of application. All of those appear to cost an arm and a leg, at least for the quantities that would be needed to build (e.g.) a piece of furniture. And then there’s solvent-welding the polypropylene (PP). That is, finding a solvent that will dissolve PP, dissolving some pieces of PP in that solvent, and then using that as if it were glue. I strongly suspect that either approach — specialized glue, or DIY solvent-welding — requires a nice clean PP surface, involving a lot of complicated surface preparation, and that the ink firmly bonded to the typical campaign sign would interfere with that.
Dare I say this? Even duct tape is iffy. The same factors that make it hard for glue to stick, make it hard for tapes to stick. And surface preparation for taping is not easy (e.g., lightly torching the PP surface). All told, taping or gluing this stuff seems like a lot of work, on the off chance that you can get something to stick firmly.
The upshot is that I’m going with mechanical fastening only.
Never in small amounts
I find most plans for upcycling or recycling of materials to be of little value. Most involve using small amounts of materials. Most involve creating something for which there is a very limited demand. The results tend to be more of a novelty than a way to divert significant amounts of material from the landfill.
Contrast that with using campaign signs for the sides of raised garden beds. That used up a lot of material, slowed down the inevitable progress toward the landfill by years, and avoided consuming considerable amounts of virgin materials.
In this case, I have a stack of roughly 35 campaign yard signs, or about 100 square feet of Coroplast sheet. Pre-cut into neat 2′ x 1.5′ pieces. So I’m looking for a project that will use up just about that amount of material, and give me something useful in return.
Revisiting cardboard furniture
Source: Google search
In Post #887, I did up a quick summary of the various construction methods used to create corrugated cardboard furniture. I’d guess that just about anything you could build as corrugated cardboard furniture could also be built out of Coroplast.
So if you are stuck for ideas, you can look up cardboard furniture plans. As long as they don’t depend critically on glue, they ought to work with Coroplast.
As I see it, the main approaches to creating weight-bearing structures for cardboard furniture are:
Simple stacked sheets.
Source: Homedit.com
Folded beams
Source: Time, inc.
Structural grids (with or without surfacing materials):
Source: Planet Paper
Totes
Source: Storage Techniques for Art, Science, and History
It seems worth mentioning that a lot of lightweight commercial bins and totes are made from folded and fastened sheets of Coroplast. It’s such a common use that there’s even a market for used Coroplast bins and totes.
You can find lots of different plans on the internet for constructing Coroplast totes, bins, boxes, and so on. They all boil down to folding a sheet into a box shape, and then somehow fastening it together at the corners. In the example pictured above, the author constructs a sort of “rivet” out of hot glue, and uses that to fasten the corners mechanically (reference).
Here, I’m shooting for something larger, to use up more Coroplast signs.
From dead campaign signs to structural integrated panels.
Source: Builder Bill
I’m going to turn my pile of used Coroplast into some structural integrated panels or SIPs. In this case, the SIPs will be flat, rectangular wooden frames, faced with coroplast sheets, and filled with … probably scraps of insulating foam board.
Like a hollow-core door, if you’ve ever dealt with the insides of one of those. The entire frame around the rim is solid wood, and so has enough strength to hold fasteners and hinges. But the broad flat surfaces are just thin, rigid sheets backed by some hollow, honeycomb-like structure.
As long as those rigid face sheets stay firmly in place, the entire unit ends up being quite strong, given the light weight. Far more than you might reasonably expect. This is why (e.g.) you can easily use a hollow-core door as a table-top, even though the individual face veneers are far too flimsy for that use.
I think this takes good advantage of the strengths and weaknesses of Coroplast. And it allows me to connect the Coroplast to the structure using a (hardware) staple gun, which is about as fast and as lazy as it gets. But all the connections subject to high point loads — the sort of connector that would pull out of a thin plastic sheet — can be made through the solid wood edges.
And it’s generic. I’m going to use this to build a little knock-down insulated shed for my composter. But nothing would stop you from (e.g.) building furniture this way. Bookshelves. A larger shed. A lightweight travel trailer. Anything that can be made from rigid flat panels can be made this way, within the strength limitations of the materials.
From structural integrated panels to winter composter cover.
At this point, putting the composter cover together is just a matter of connecting the panels made in just above.
Ideally, I’d like to have “knock down” construction — something that can be easily disassembled and re-assembled without tools. (That way, I can store it away easily during the off-season). But in the end, this is only going to take four long screws to hold it together. So I’m just going to screw it together.
How this actually goes together is going to depend on what scraps of lumber I build it out of.
Conclusion
In this post, I figured out how I’m going to use up a lot of 1.5′ x 2′ Coroplast campaign signs. My proposed method is to build a bunch of “structural panels” out of those signs. That is, thin wood frames faced front and back with Coroplast sheets. And then use those rigid panels to build a structure.
This approach:
- Uses up a lot of signs.
- Doesn’t require gluing the Coroplast sheets to anything
- Uses (hardware) staples as the main fastener
- Avoids putting high point loads on the plastic sheets themselves, by placing all the “structural” fasteners into wood.
- Is flexible — just make the panels different sizes.
All I have to do now is to make that happen.
I’m now going to test that, by building a winter cover for my composter, using that “structural panel” method. Assuming all goes well, the construction of that should be documented in my next post.
