That is a bummer, oh well Sig it is.......Rand-O-Fil Silver is basically dope with Silver pigments added. I don't want to mess with sanding silver dope, don't know why they did this but I am sure they have their reasons. Normal balsa sanding sealer was nothing more than dope with an additive to help with sanding. The additive was not really a filler unless you bought Aerogloss Fillercote. I have used regular dope to seal and fill balsa grain for years with no issues.