ultrahold is mixed with the solvent tolunene which is very quick to evaporate...that's why it has a strong chemical odor. You have to replace the cover each time you dab the brush to prevent this. We all have learner the hard way. I've never been able to use all of a jar of ultrahold...oh, and don't knock it off the counter..EVER...NIGHTMARE! and don't try to thin it with alcohol...it turns yellow and is not usable