You can brush it on too. I have done that before. Just very thin. And just feel the glass. When you put extra MEKP on glass, the glass will harden underneath, and a thin oily layer will be left on top. You don't have to wait for that oily layer to cure, just make sure the glass itself is hard and then wipe the oily layer off with a rag. If you ever do glass again, a good thing to do is heat whatever you are covering first. I usually put a halogen over top of it for a good 10-15 min first before laying the glass down. You really don't need more than 1% MEKP, 2% at the absolute most!