Originally Posted by ghrocketman

Sig Sanding Sealer needs at least 1 part thinner to two parts sealer.
It is very thick.
Do not use without thinning. It will be gummy for days if you don't thin it.
You can use straight Acetone to thin it, but it may dry way too fast for your liking.
If you don't want to buy commercial dope thinner, I would use straight Toluene or MEK to thin it instead. A mix of all three 8n even proportions makes an even better thinner.