longdan

Is there some way that balsa sheet can be 'shrunk' like covering film? You are probably wondering why I need to do this. I have just finished building a wing. The plans called for 1/16 sheeting on the top of the leading edge only, leaving the bottom open. I don't really like this so I sheeted the bottom with very thin (0.8 mm) sheet, both to add a bit of strength and to preserve the airfoil shape after covering. As with all my models, I painted the balsa with watered down PVA (white) glue to seal the grain and to harden the wood and make it more resistant to dents. The thin sheet soaked up the water and swelled up between the ribs. As it dried, it shrunk a little bit, but not back to its original size. The swelling seems to have occured in one direction only, like it has pushed the grains apart, but not lengthened them. It looks terrible and I think the effects will be very bad. Anybody know any way to bring it back to its original size?

jetmech05

sand paper applied vigoriously

stang

My Feedback: (1)

Hobby knife, apply vigorously.

bigchap

bad temper,applied vigorously!
on a more serious note,no,there is no way of shrinking it,start again.

da Rock

A sanding block that spans 3 or 4 ribs works great if you don't bear down on it. Makes lots of dust but works great.

Jim Thomerson

Try some non plasticized buyterate dope. Several coats and let it dry a day or two between coats. I use the PVA thinned down also but have never used it on sheet that thin.

longdan

Thanks for all the tips (well most of them anyway). I tried the butyrate dope on a small part of the affected area to see if it would work, but it wouldn't soak in due to the PVA I had already sealed it with.
But, for those interested, I managed to almost get it back to how it was. I wet it down again with water, and the balsa swelled like it did before. I then used a piece of very thin perspex with lots of weights on it to press down on the whole surface and left it to dry. It pushed most of the swollen area back to where it should be. Now It just needs a bit of microbaloon filler and a bit of sanding and it will fine.

jeff1127

Next time try sealing both sides before gluing it onto the frame. I know that's a little late for this.

Shuttle RG

80 grit