Canvas outside and 1/4" ply inside?

[rowerwet]

It never ends...

[KCStudly]

Where did this "cupping" issue come from .... First time we've heard that one eh ??? Get the shovels out !!! Again !!!

"...a shrinking skin can WARP a surface dramatically." - GPW said on 3/14/2012 here: http://www.tnttt.com/viewtopic.php?p=920223#p920223

Sucks getting old, doesn't it!

Just saying, it happened and we talked about it a lot... and you are also correct, the solution seems to be applying the fabric over the whole build. Some people just don't want to have to do the inside from the inside out, so they will have to be aware of this possibility, and work to avoid any issues.

Not a show stopper, just something to be aware of.

[GPW]

Actually as written , that was on model plane wings , delicate structures compared to two inch thick foam ... With a lot of folks covering the inside with bedsheets , plywood or chipboard , we don’t see the possibility of a lot of warping from the inside covering ... And proper installation of the outer covering with allowances made for shrinking ( like pre shrinking the fabric and not stretching it too much ) a lot of warping of flat pieces may be avoided ... ESPECIALLY once the foam is covered on both sides , equalizing the stresses imposed ...

I just finished gesso ‘ing two 24” X 48” masonite panels to paint Art on .... painting both sides , prevented any warping , paint surface still dead flat .... painting one side would surely warp , as we’ve proved to ourselves in the past ...