I tried multiple thinning ratios and really like 50/50, dries fast and super easy to sand. The less thinner I used, the longer it took to dry and harder to sand. At 50/50 the filler additive works great and easier to sand when compared to Brodak. Also thinned 50/50 it reminds me of old Aerogloss balsa Filler. I am thinking about sealing the balsa next time with Sig dope, 1 or 2 coats then applying the sealer.