• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.

Straightening foam board?

con244

Senior Member
#1
Does any one have any ideas on how to straighten some warped sheets of foam board? I left some sheets out in my workshop and they are all bent out of shape.
Con
 

vk2dxn

Senior Member
#2
When I crinkle my foamys I put the bunged up area in hot water or poor hot water over the area and it springs back to shape
 

tramsgar

Senior Member
#3
I painted foam board quite wet once, and it warped. When I painted the other side, it warped back straight =). So if you got "regular" warping try to carefully apply moist to the opposite side (water makes the paper shrink).

If that does not work, do like wood craftsmen do: look at your piece of material and visualize what could me made of that shape...
 

con244

Senior Member
#4
Ooooh, so the plane is in there I've just got to remove the bits around it :p. The sheets were up against the wall so they may have gotten more exposed on one side than the other. I will try turning them maybe that will even them out. Foam board is quite expensive over here in Australia almost $11 a sheet.
Thanks guys,
Con

I painted foam board quite wet once, and it warped. When I painted the other side, it warped back straight =). So if you got "regular" warping try to carefully apply moist to the opposite side (water makes the paper shrink).

If that does not work, do like wood craftsmen do: look at your piece of material and visualize what could me made of that shape...
 

Craftydan

Hostage Taker of Quads
Moderator
Mentor
#5
If it's nearly trash already . . .

option 1: Several of the models have folded shapes with long edges. If you're careful, you can use the folds to pull the sheet back into shape. align the bow along the long straight folds, with the convex side pointing outward. To make the turn, it'll have to be straight along the fold. watch for warping down the length and alignment of edges beyond he folded areas -- you might have to scrap it anyways.

Also, If you're using Adam's foamboard (Which from your locale you're probably not, but others here do) *any* moisture on untreated paper will cause the sheet to separate from the foam. Here in middle Georgia the humidity alone is enough sometimes.

Which leads to option 2: strip the board. The naked foam is very compliant and will likely flatten on it's own with the paper removed. The stripped foam is about 4-4.5mm, and has about 1/2 the weight. It can be laminated for strength or shape with *WATER BASED* polycrylic (really like minwax's polycrylic , paint on, press & hold flat and give it 6-8hrs to cure), and can be recovered by packing tape, or coated w/ polycrylic and painted.

Now several of the methods in the swappables rely on the paper, so a stripped & tapped board might work for a particular swappable -- might not -- but this is only a *SMALL* subset of plans that can make a sheet of foamboard fly!
 
#6
You can use an iron to smooth it out. Use old cotton towel for dollar tree board if the paper now is on. Steam works also. Practice makes perfect. Test on old scratch piece. Hot water is how foam is made
 

RoyBro

Senior Member
Mentor
#7
...and they are all bent out of shape.Con
"Bent" as in something bent them? Are they mangled? Squished? Or are they simply warped?

How bad? Often if you just reverse their position for a day or two, maybe with some weight on them, they will straighten out. How many sheets are we talking? If only a couple, you can always buy new sheets for large pieces like wings, and use the warped ones for pieces that have structure like the fuselage or power pod. Those A and B folds tend to straighten foam out as well.
 
Last edited:

rcspaceflight

creator of virtual planes
#8
At least with Dollar Tree foam board, it is the paper that warps, not the foam. I started removing the paper and replacing it with packing tape, it's not as rigid, but can handle more abuse that way.

If you can easily peel off the paper, that might be a way to salvage it. Or re-wet the paper and fold it flat some how. I see other people have better suggestions that I.
 

con244

Senior Member
#9
Thanks for your suggestions Dan and others. Don't know what brand this foam board is. I do know that removing the paper is a nightmare and generally leaves the foam in very poor condition. I did turn the board around over night and it has straightened some. I think the moisture in the air on one side and nothing on the wall side of the board may have caused the problem so I've just got to remember that the board has to be exposed to the air evenly before a build. I always paint the finished model so it is not a problem after the build.
Con
 
Last edited:
#10
I have the same problem, but how do I straighten the foam board that's already put together in a build like the FT nutball/flyer? Anyone got some ideas? Thanks.
 
#11
Just flip it over for a couple of days. It will straighten on it's own. Mild warping of the board will not cause any real problems for most parts because most of the building techniques force the board flat.