Bowed FoamCore


Grumbler in Training
Jul 22, 2004
Indianapolis, Indiana
Okay, this is my first post so go easy on me.

I have a customer who has some blown up pictures that have been mounted to foamcore. They have been hanging in an office unframed for some time and have bowed. Looking at the picture, the middle is sunken in. He wants them framed with glass but no mat. My thought is to lay the picture face down on something soft so as not to scratch the picture, slap some glue on the back,lay some sort of plywood over that and then weight it down and let it dry.

Any thoughts? What kind of glue? Is plywood the way to go? I don't think another piece of foamcore would be strong enough.

Thanks for any suggestions you can give me.

Welcome Laura

You have a no win situation with a customer.

-bowed fome center board with a photo mounted
-customer does not want glass.

have the customer order a new print.

I do not think it is worth the risk. BTY you would probally need 1/2" plywood if you would happen to try to mount it with contact cement or carpenters glue.
Welcome Laura,

The bowing is caused by the uneven expansion of the foamcore. It can't expand evenly because the photo mounted on the front.

Lay the mounted piece face down, litely moisten with a rung out sponge and weight over night.

The photos shoud now be flat enough to frame.
Yo', Laura,

We'll be gentle.

If you have access to a dry mount press, you should be able to get (most of) the “bow” out of it. Moisture is the likely cause of the bowing.

Start with the convex side up against the platen and heat it to somewhere around 180°-200° for a minute or so. Do this several times both to the convex and concave side until the foam board is reasonably flat.

Once you cannot do any better, “counter mount” either a scrap photo of the same size, or barring that, a sheet of Kraft paper of the same size to the opposite side from the photo (in Bill-speak, the verso – "word of the day" – June 15, 2003).

It generally works well enough so that you can usually frame it.
Bill is right in suggesting that you countermount something onto the backside of the foamcore (after flattening it as best you can). The combination of a piece of photo/print paper and the drymount adhesive on one side only has sealed that one surface of the foamcore and added a restrictive tension to that side which does not allow it to expand and contract evenly during environmental changes in temp. and humidity. (This will also happen when the surface papers aren't tensioned properly on the foamcore during manufacture). So, when the temp/humidity rises the board tries to expand but only one side of the surface papers can expand fully, hence the bowing towards the side that can't expand evenly.

I would think that a countermounting of most any sturdy paper would help the problem as the drymount tissue would serve to seal the back side of the foamcore. If you can find a scrap piece of similar photo/print paper to the one mounted on the front side, this would be optimum as the restrictive tension applied to the front side of the foamcore would also be close to the same tension on the back side.

Originally posted by LCombs:
They have been hanging in an office unframed for some time and have bowed.
A really nice person would be able to resist the temptation to say "See, that's what happens when you try to cheap-out on your framing."

Okay, I don't have access to a dry mount press. I am currently trying the idea Dave suggested - lightly dampening the back side with a rung out sponge and then laying it flat and weighting it. It can't hurt to try that one.

The pictures are about 16" X 20".

My next question is what will keep this from happening again even after it's framed? Do I just put it in the frame with a stiff board behind it?

Thanks so much for your replies!

Candy, I was on my best behavior that night.

I'm sorry, Laura. I know I'm not being helpful. You have gotten good advice from other members of the forum and I have nothing to add to what has already been said.

Except... Welcome to The Grumble!