Hold my beer - I'm gonna try try something...

[FrozenNorth]

Even a vinyl or aluminum siding product may be worth considering, I am just thinking of products already designed to be outside anyway.

[Lyndell Thompson]

Morris have a look at this page. Definitely not smooth or paintable but lasting .......... yes. 50 year warranty......life expected to last 100 years. Gottem on my house! They make flat sheets for for trimming aroung chimney's and the like. Lots of color and pattern options. May not be what you want but the longevity is in the range you require. Decra is not cheap......you didn't mention price range. Lyndell

[dadiOH]

May have lasted much longer, don't know, 20 years was the length of time I had the stuff before selling.

[WayneJ]

Besides being expensive, 0.002 stainless foil is THIN. If the completed box gets any significant rough handling you should expect one or more cuts through it.

You mention exposure to salt, if the stainless foil is in contact with salt water (or other source of chlorine ions) in the absence of oxygen it will corrode fairly quickly. Foil 0.002" thick doesn't allow for much corrosion. Salt water trapped between your box and another surface or even a layer of saltwater mud can exclude oxygen to the degree required.

WayneJ

[Zz Yzx]

'k, I'm intruiged. Can I ask what the use of these boxes is?

-Zz

[Morris Dovey]

Solar heating panels. They mount in the sunny side of a structure to keep it warm. Photos at

[Morris Dovey]

The metal doesn't appear to be a large cost factor. I thought about flashing, but my flashing choices here appear to be aluminum and copper.

Copper is expensive and changes appearance (which might be ok with some customers, but not with others). Aluminum is a little better with respect to appearance, but would perform poorly on a saltwater coast. I chose stainless primarily because I want it to hold up well not only in Des Moines and Sarnia, but also Edinburgh and Oslo...

...for a very long time.

*This* is a big part of what I was after. Thank you! I'll investigate.

It's probably not a major factor, but I still don't want to add any more mass than necessary. Already I'm discovering that these things are getting heavier every year...

[whit3rd]

In terms of moisture and fungus attacking the wood, your structure will need roof-like coverage; that means flashing in addition to the foil/cement that protects the large flat surface. Stainless steel will just be a kind of paint, with all the problems of paint (nicks or cracks will grow into major flaws). Some ventilation will be required, too, or the protected wood will never have a chance to air-dry in case of accidental moisture.

Instead of looking at just the protect-flat-surface part of the problem, you need to examine edge and corner and overlap areas, and apply appropriate flashing there. It doesn't seem to me this will be easy.

If dissimilar metals are nearby, and if they touch the stainless, you can expect accelerated corrosion of the metal. Copper and lead roof structures have lasted centuries, so there's certainly hope for success.

[Swingman]

Have you looked into any of the vinyl products? Vinyl clad wood seems to have a pretty good track record.

[Lew Hodgett]

RE: Subject

Trying to laminate a wood core with fiberglass, metal, etc is at best a very difficult thing to do.

Ultimately the adhesive will get you and wood core structure is heavy.

Stainless steel in a marine environment is a loser.

"Stain Less" are the operative words.

Unless you use 316L, forget it.

Faced with your situation, I'd start talking to the "Plastic Wood" people.

Seems like a natural, especially since the offer dimensional lumber sizes.

Lew

[John Grossbohlin]

Carbon Fiber over balsa wood like on a Corvette should do the trick... Strong and light. ;~)

John

[Lew Hodgett]

Two basic problems:

Carbon is still on allocation

Balsa sucks.

Ever have to redo a boat deck that has a rotted balsa core, from getting water in the balsa core?

Lew

[LDosser]

While you are there, maybe check out Undercoat. Some of these folks should be able to give you the UV tolerance of their products. What do the utility companies or railroads do?

[aeroloose]

How about you forgo the wood & SS sheet idea, and think about extruded aluminum C-channel instead? You can frame your box, have the edges welded seamlessly, and get a nice plasma or hard anodize finish applied to the final assembly. These finishes have excellent aesthetics, and will resist handling / installation abuse well, as they're part of the surface micro-structure of the metal (vs. external coatings). Overall weight is reduced, too, so that might be beneficial.

Tabs could be added to the inside to attach mountings, glass, solar panel parts, etc. If you're concerned about heat loss or conduction, perhaps the inside section of the channel could be sprayed with foam or other insulator.

Food for thought ... it's not woodworking anymore, of course ... :)

Aero

[LDosser]

I'm not sure stainless holds up all that well in salty applications. I've seen supposedly stainless measuring cups pit when I use them for saltwater aquarium water preparation. Brass might hold up better in a salty environment, but I don't have a clue about that.

[Markem]

Perhap copper it will last and age well.

Mark

[Lew Hodgett]

Brass in salt water is strictly a loser, the zinc leaches out leaving a structure that will crumble in your hand.

Stainless Steel is no winner either.

"stain" and "less" are the operative words.

18-8, of which is what most cooking utensils are made, will pit right in front of you, if left to continuous exposure of salt warter. 316L, about a 35% price premium, will last a little longer, but silicon bronze is your best shot.

Lew

[Lew Hodgett]

Only problem with copper, other than initial cost, is that it would get stolen before it gets installed, for it's scrap value.

[Mark & Juanita]

... snip

Haven't done anything exactly like this, but I'd be concerned that 2 mil steel covering is going to be susceptible to all sorts of damage from handling and pre-installation problems. That would leave a channel for water infiltration that could result in worse long-term damage than exposed but painted wood. 2 mils is really more tin foil than covering.

[Morris Dovey]

Hmm. Thanks. What I've been looking at in my catalog are Type 321 and Type 309 stainless tool wrap - probably good for their intended purpose (making a quick "airtight" envelope for heat treating small parts), but not necessarily great for mine.

I doubt solar heating panels will be continuously exposed to salt water

- but I'd like 'em to hold up as well as possible in coastal areas. I could live with a 35% premium if 316L holds up significantly longer than

309 and 321, and I've added the search for silicon bronze foil to my to-do list.

I'll do my own research, of course, but do you have a notion of the difference in cost between silicon bronze and, say, 316L stainless? And are you aware of any mechanical properties that might make it more/less difficult to work with?

I have a local customer who's volunteered to be a guinea pig for Type

321 panels, and I don't expect any salt problems here - so building his order will be the learning exercise in applying a metal jacket to these things. Since I have you "on the line" would you care to comment on Lee Michaels' suggestion of possibly using an epoxy as the adhesive?