How to tint glass with uneven, jagged silicone or gasket.

Method 1: There is no way to get clean edges on gasket or silicon that has become jagged or uneven after years of deterioration. The only way tint it properly is to trim it straight with your blade, or cut it all off completely and redo it - either with new gasket or new caulking. Alternatively, you can tint right up against the silicon and then add more caulking later on, but this will leave you with a bigger silicon perimeter.