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Forum topic by Rayp posted 01-07-2013 07:16 AM 724 views 0 times favorited 12 replies Add to Favorites Watch
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Rayp

4 posts in 719 days


01-07-2013 07:16 AM

I make artwork on thin copper sheet that I want to mount onto wood panels (with standoffs on the back to give a floating appearance) to be hung on a wall. The copper sheet is mounted to the wood with DAP contact cement. For some of the smaller pieces (8”x11”) I’ve used ¼” sandy ply from Homedepot, but it has tended to warp. For bigger pieces (2’x2’) I want to use something about ½” thick.

Can anyone recommend the best wood to use in ¼” & ½” thicknesses that won’t warp? The pieces are meant for indoor use, but should also be able to hold up to outdoor use in sheltered areas and the humidity of a bathroom. Cost is a consideration too. I’ve thought about using MDF, but I don’t know how well it would hold up to any humidity or how well it would hold the screws used to attach the hanging hardware (eyelets & wire). I’m not a wood worker so any advice is appreciated!


12 replies so far

View blackcherry's profile

blackcherry

3209 posts in 2576 days


#1 posted 01-07-2013 02:07 PM

Baltic birch plywood extremely stable and you could dye stain for a striking contrast to your copper art

View Triumph1's profile

Triumph1

841 posts in 1832 days


#2 posted 01-07-2013 02:27 PM

The problem could be that you are only gluing the copper to one side of the plywood. Now one side is copper and one side is wood. They will expand and contract differently causing warping. The standard in veneering is to glue/attach something to the two sides at the same time to equalize the wood. Now, I am not sure what you could put on the other side opposite of the copper. I know copper is at a high so I am sure you don’t want to waste a piece on the back. You might want to experiment a bit.

If you use MDF you would probably have to seal it. As for mounting screws a little trick I use is to pre-drill the hole and then apply super glue (cv) into it. The MDF seems to suck that up nicely and then it hardens.

-- Jeff , Illinois Please...can I stay in the basement a little longer, please!

View Rayp's profile

Rayp

4 posts in 719 days


#3 posted 01-07-2013 09:47 PM

Thanks for the information guys, I’ll look into your recommendations and give them a try!

View bondogaposis's profile

bondogaposis

2760 posts in 1104 days


#4 posted 01-07-2013 10:21 PM

MDF would be another option. It tends not to warp, but it cannot get wet.

-- Bondo Gaposis

View Jim Finn's profile

Jim Finn

1745 posts in 1674 days


#5 posted 01-07-2013 10:34 PM

baltic birch is what I would use.

-- In God We Trust

View BentheViking's profile

BentheViking

1755 posts in 1317 days


#6 posted 01-08-2013 02:14 AM

possibly try some bamboo? It might do better in the wet areas than the mdf or baltic birch that others suggested

-- It's made of wood. Real sturdy.--Chubbs Peterson

View Loren's profile

Loren

7826 posts in 2400 days


#7 posted 01-08-2013 02:31 AM

I think Baltic birch would be good. It won’t stay totally flat
unfinished in this application.

Even a simple finish like paste wax will help stabilize the
plywood a bit.

Home Depot is not a good source of stable plywood. I have
seen they are stocking some ply that appears to be
cabinet grade now, but time will tell if the stuff is
equal to the name brands you get from plywood dealers.

-- http://lawoodworking.com

View lowellmk's profile

lowellmk

61 posts in 725 days


#8 posted 01-08-2013 02:31 AM

I think I would use Baltic Birch as well. I think you would be hard pressed to find this at Home Depot.

-- Wag more, bark less.

View AandCstyle's profile

AandCstyle

1486 posts in 1010 days


#9 posted 01-08-2013 02:42 AM

For exterior applications you could try MDO. It is expensive, but it is used to make road signs. I agree that if the copper is glued to the substrate, something is needed on the back side to prevent warping.

-- Art

View Rayp's profile

Rayp

4 posts in 719 days


#10 posted 01-08-2013 02:47 PM

Thanks for all your replies, it’s definitely given me things to think about and try. It looks like Baltic birch plywood is the leading suggestion, so I’ll probably start with that…maybe with a coating of some sort on the exposed back side. Loren suggests paste wax. Any other coating suggestions, a shellac of some sort?

View Mark Kornell's profile

Mark Kornell

664 posts in 1283 days


#11 posted 01-09-2013 04:02 AM

Baltic Birch is definitely a good choice, for 1/2”. 1/4” BB will warp, just like regular ply. For that application, I’d suggest hardboard (which is available at your local big box retail outlet, unlike BB). Won’t stand up to a wet environment, but should be OK with something that is just “humid”.

For a back coating, you want something that has the same kind of permeability to moisture as does copper, which is essentially impermeable. No standard wood finishes will keep out moisture to that extent – not wax, not latex paint, not shellac, not poly, etc. Maybe a thick, bartop finish style epoxy. It is the uneven moisture absorption that leads to the warping, not moisture absorption, per se.

So, look for something like aluminum sheet (paint it to prevent oxidation), thick mylar, maybe even countertop laminate.

For that matter, what about making your backing board out of lexan or plexiglass? More expensive, but no humidity issues, ever. Paintable, so you can disguise what it is…

-- Mark Kornell, Kornell Wood Design

View Rayp's profile

Rayp

4 posts in 719 days


#12 posted 01-10-2013 12:56 AM

um…all good ideas. I’m thinking I’ll probably go with baltic birch and seal the exposed back as good as I can. Plexiglass would solve all warping issues, but as you said, a bit more expensive. Thanks again everyone, I appreciate all your feedback!

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