question on cleaning old sealant before applying new

I picked up a bottle of something called Contractors Solvent from the specialty plastics shop in town. Spray the stuff on and the silicone or sealant was coming off by itself. Get a coupe of silicone removal tools as they do wear out. And a heat gun is great for the stubborn stuff. I know, I was on my 5th roof all weekend dealing with layers of old sealant.