On my TomCat I have been using Brodak silkspan and dope. 5 coats of 60 thinner-40 dope. A light sanding, then applying Brodak sanding sealer, light sanding between coats. I don't have enough sealer so I added about 50-50 dope and thinner, then added some microbaloons, mixed well and it looks just like the sealer. Does this make up the same kind of sealer or should I not of used the microballoons?
We used to use Microballoons as a filler for CYA and resin; Baking Soda also worked. Talcom powder was the medium for Clear Dope.
I also recall a note on Talcom Powder: Avoid the scented type, as it had an undesired ingredient. Corn starch was a substitute for Talc.
You are essentially creating your own sanding sealer. I use the exact same mixture on my silkspan-covered parts for final finish. Some people will say use corn starch, some say use talc, but I find Micros the best. When I was young, I would use saw dust, because I didn't know anybetter. Elmers and sawdust was my filler and dope and sawdust was my sealer. Actually worked pretty well, considering.