I used vinyl spackeling to try and fill in a long crack in a sheeted wing and the water content cause the balsa to bubble up, so now what do I do ?
I have been using vinyl spackeling since I read Harry Higgly's book "There are no secrets" years ago and this is the first time to have a problem I expect because of the thinness of the sheeting and the large area applied to. BTW it did not fix the crack it just can through the spackle :
I should have known better cracks need either to be pulled together and bonded or filled with something flexible.

thanks
Jay

Any time I've need to warp or bend balsa, I've applied water to the side I wanted the balsa to bend away from. So if you apply water to one side of balsa, those fibers will expand and warp away towards the side that doesn't have the water applied to it. It's tough to control, but for example when you are shaping balsa over a leading edge, it works just fine. I don't know how far into your project you are, but consider your options. Replace the wood with a new sheet. Try to warp/bend the balsa to what you need. Many kits will suggest using opposing warps to make a straight wing. Like with spars. That does work. If its way out of control and warped beyond fixing, buy a new sheet.

It sounds as thought the balsa was not bonded to well to the wing structure. Is this a built up wing or a foam core? Foam core, clean as much Spackle as you can off. get some water based glue, such as good ole Elmers, thin with about 20-25% water, use a thin plastic sheet as a way to get the glue under the balsa, get as much area covered as you can. Either make a cheap vacuum bag out of a shop vac to hold the balsa as tight as you can. If you can cut a foam block into the shape of the wing you could use that as a mold to squeeze the balsa tight again.

Built up wing, drill small holes along the top of the ribs, wick ca into the holes to glue the balsa down again. Fill the crack with a long sliver of balsa, glue well, sand. I use Elmers with the orange top. It is the color of balsa, sands like balsa, take paint, covering, like balsa.

Lots of work to fix a warped piece of would.


Buzz.

In the past I would hold the panel over a steaming teakettle and counterwarp the wing panel. Bend more than is needed as it will relax and some of the counterwarp will disappear. It will take several hours to dry so a jig to hold it in place will be necessary.

The best filler for cracks in wood is..... drum roll..... WOOD. Sliver a piece of same/similar balsa small enough to fill the crack tightly.. and take a sliver of CA glue on a toothpick... working quickly, dab the CA into the crack... stuff your sliver in.. block sand flat. You won't even know the crack was there. Guaranteed.

Dents are a bit of another story.. but you're probably on track with filler for any dents... but there's a few other tricks for those too.

Ammonia is the best chemical to use to straighten wood. Brushing it on wood or injecting it into a wing relaxes the lignin that is the natural glue that gives the wood its strength. The Ammonia will cause the lignin to remain soft until it dries out once again.

In the mean time you can re warp the wood to your satisfaction. The wood will then keep it's new shape.

Dan

I've had numerous cases of warped wood that I would have loved to get leveled out. I've tried several methods but none of them worked. If you fin a way to do this, let us know.

Wood warps because of swelling of fibers (I think anyway). Once that's happened, it's heck to get things flat. If you find a solution, it's the holy grail of model building.

Dave