To prevent damage from exposure to the environment (rain, snow, salt, UV, bugs, etc) I've been thinking about wrapping the outside of some wooden boxes in stainless steel for some time now.
The rough plan is to apply spray adhesive - something similar to
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the wood and then very carefully apply 0.002" stainless steel foil similar to this stuff
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the adhesive and use a roller to ensure good contact / smooth surface.
I've never done anything like this before, neither the adhesive nor the foil is particularly cheap, and the wooden boxes are expensive enough to make me nervous about screwing up even one full-sized test.
Has anyone tried anything like this (first-hand experience) or know of someone else who did? Did it work and if not, why not?
Does anyone know of more suitable/better/longer-lasting materials?
Any technique suggestions that might make the job easier or provide longer-lasting protection?
I wonder if you sprayed the box with that truck bed liner stuff [ rhino liner?] might work. seems like it would seal every thing tight and last a long long time.
Please. I'd like to take a look - and I confess ignorance as to suitability of particular adhesives.
This whole exercise is intended to maximize the useful lifetime of the boxes so, yes, I do care about the long term hold. I'm not committed to aerosol application - I'd just wanted to avoid a too-thick mass that might uglify the finished product...
is a heat gun. Contact cement and heat don't get along. Something to keep in mind. I thought of that, because when Morris is around, the sun can't be far away. What? Waitasec....
Two sizes: 48" x 72" x 8" and 96" x 72" x 8". I only need the s/s around the four 8" sides of the box.
I'm still experimenting with wood types, and my material choices open up dramatically if I can ensure that the material is completely shielded from the elements.
Anticipating your next post, these /will/ be perched in the sun - but shouldn't be subjected to temperatures higher than about 150°F/65°C or lower than about -40°F/C.
I'll follow-up on that. I'd like for these things to be good for a century or so in a high-UV environment, so I'd more or less ruled out plastics. A trip to the junkyard to look at old pickup might provide me with some notion as to how bed liner material holds up...
I've considered that - but wood has properties that make it particularly well-suited for these boxes. It appears that it's a lot more economical to enhance outer surface of wooden boxes with a small amount of metal than it is to deal with the thermal headaches inherent in an all- or mostly-metal box.
The boxes already have some 1/8" aluminum trim that I worry about not holding up well in coastal/salty/high-pollution areas... :(
I'd think a thin layer of foam/etc. on inside would be far quicker/cheaper and at least as much thermal resistance as 3/4" ply for the thermal part...the structural end could still be an issue, granted.
How big are the boxes out of curiosity?
That could be issue w/ common AL alloys, certainly. Altho we had trouble w/ some SS's being susceptible to grain-boundary-site initiated corrosion in some areas in paper mills, too (specifically bleaching operations w/ Cl processes) so depending on the environment even there may need to consider the specific alloy.
You didn't say what kind of wood, what the boxes are for or how important appearance is. I'm assuming plywood since laminating anything to solid wood is iffy.
If appearance isn't terribly important - and if it were me - I'd laminate the ply with fiberglass and polyester (not epoxy) resin, then paint it. I've never done that where it snows but have many times in the tropics...lots of sun, heat, salt from the ocean. It works well, had stuff like that for 20+ years.
The potential problem with *any* lamination is DElamination...once water gets between the two surfaces rot starts quickly. And how about the inside of the boxes? At the very least, any laminate should be continuous over the wood edges.
I'd like smooth paintable surface (to at least not clash with house siding) without penetrating fasteners. The wood, if kept painted, should last more than 20 years; and I'd like for these things to last for at least 50 years even if not maintained at all. I'd also like to keep weight down to control shipping costs.
I can't imagine the adhesive holding up that well in these circumstances. Particularly if it gets hot inside of that box. If you tired this, I would have to get some kind of assurances from the manufacturer that it would be suitable for this application.
What you need is some kind of coating over the outside.
Fiberglass comes to mind. I have seen fiberglass work well, but it deteriorates over time. It would need to be refreshed from time to time.
I used to work for a solar heating company that made the parabolic heaters for pools. We thermoformed everything. We got the metal coated mylar in sheets from the plastic company. We then just heated up the thermoforming machine and made up the parts. We were interested in its reflective properties.
Since you need a protective covering, you wouldn't need the reflective coating. Would something like this work? You could talk to the plastics company guys. They are very knowledgable. It is easy to make a thermoforming machine. You like to make things low cost knockoffs of industrial machines anyway. You can get plastics that last a million years. Attaching the protective plastic cover to the wood would be the tricky part.
And also, a spray on material could work as well. I know nothing about this. I know that somebody suggested the truckliner stuff. Could you go to a truckliner guy and have him spray the unit?
Is there some other kind of material/process that is sprayable? You might look at heavy duty spraying eqipment and talk to those guys. They may be able to give you some suggestions as to who talk to.
And you can always ask Lew for his epoxy suggestions. :)
Not sure about the painting or colours available, but how about some of the flat roofing type products (most are probably black I suspect, but there may be options).
That .002 SS foil would stick to wood with Wilsonart 3000. That type of adhesive is just amazing. Weldbond is similar. Water based technology has come a long way. And as long as one side of the joint is porous, it will work just fine. Just how important is the shipping weight? Isn't size the driver in the shipping costs more so than a couple of extra pounds?
Plywood and manufactured sheet goods are a possibility - but right now I'm working with SYP and poplar. If I can completely prevent moisture from getting at the wood, then my materials choices widen substantially.
The boxes, of course, are solar heating panels. The front is glazed and the back will be out of view (inside a south wall). The interior of the box will be exposed to warm air at the same moisture level as the inside of the structure - which isn't much of a concern. What I want to do is protect that portion of the box edges that are exposed to the outdoors.
Appearance is important. I'd like 'em to look smooth, clean, and simple. Paintable would be very nice, but probably isn't an absolute requirement.
Currently I apply a wipe-on coat of poly, sand lightly with #400, and brush on a coat of white primer. The customer then applies a color coat of their choosing - but beyond that point longevity depends entirely on the customer keeping the exposed portion of the box painted, and I want to remove that dependency.
Twenty years isn't long enough. I'd settle for 50 years, but a century would be way more than twice as good. I'm determined to make these things to outlast the customer's grandchildren if I can. :)
I'm not worried about the inside of the boxes at all - they tend to be self-regulating and have good airflow.
I am concerned about the adhesive deteriorating over time (that's one of the reasons I'm looking for advice here). One of the box's design points is that all glue and sealant areas are already shielded from UV, and now I'm wanting to provide 100% protection for the exposed (exterior) wood.
One of the things I like about the foil approach is that I can fold it over the front edge of the box side so that the front edge of the box is covered. I'm planning to use a closed-cell foam weather stripping between that edge and the glazing, and a 1/8" aluminum trim angle over the edge of the glazing to protect the weather stripping from UV and to dress up the edge. By doing that, I should be able to prevent moisture entry and make the glazing removable (it's not now) to allow cleaning when needed.
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