Berryman B-12 Chemtool (part #0116) is generally quite safe on gaskets for short periods of time but should not be used for extended soaking. As for Chem-Dip, we make two different types. Part #0905 is an extremely aggressive immersion cleaner that is incompatible with most paints, coatings, and rubber components (including gaskets). It is intended for professional use and is supplied in 6-gallon buckets. Part #0996 is much safer for general consumer use, is compatible with most paints and gaskets, and comes in a 1-gallon paint can. This product can be used for overnight soaking with the exception of aluminum and aluminum alloy parts, which should not be soaked more than a few hours in total.