I have found that Sand N Seal takes 4 coats for a grain free finish. I first tried it with 3 coats and it was not quite enough. Eze Dope also works well. I am finishing up a Estes Photon Probe that I used Sand N Seal on and it worked great, will post pictures when I am done painting. I have tried applying not fins not glued to the rocket and yes it will warp until you do the second side. Also after the 4th coat you could let dry for an hour then place between to heavy flat objects and the next day it is perfectly flat. Here is my first review with this stuff. P.S I still love Aerogloss but like I said it is hard to come by. Sig makes a sanding sealer but I don't want to order it online since nobody around me sells it. All the hobby stores around me sell Deluxe materials supplies.

http://www.oldrocketforum.com/showthread.php?t=14244