How much fin warp is too much?

[Screaminhelo]

So, Estes sent me the whole DRM to replace the decals that I needed. This means that I MUST NOW BUILD ROCKET. Since I am familiar with the kit, I figured that it would be a good opportunity to tray a new technique or two. I didn't have wood filler to fill the grain, so I used drywall mud instead. I noticed a sight warp in a couple of fins after final sanding. Being a low power rocket, I decided that a minor warp is not a critical flaw and will continue with the build as is. What are your suggestions for avoiding this in the future?

 

[Marc_G]

I seal balsa fins with thin CA before doing any filling with carpenters wood filler, drywall filler, or any other water-based filler. In fact I like to seal with CA even before using lacquer/MEK based spot fillers (3M&Bondo glazing/spot putty), because the sealed fins are very hard once the CA sets up and I can apply more pressure while sanding without worrying about reshaping the fins.