The answer to this depends on the type of material you're using: Hot Crack Filler or Cold Pour Crack Filler
Hot Crack Filler
If you're using a hot applied crack filler and filling the applicator using a stationary melter, then your best bet is to have a plumbers torch on hand (sold at your local hardware store) and burn off any rubber that might have built up during use or caused moving parts to seize up. Pour pots, for example, will sometimes have the valve freeze up between uses. Simply heat up the left over rubber and this will free up the valve. We recommend draining these units of all rubber after the job is done and burn off any excess rubber ahead of time to make sure you're ready to go for the next use.
Cold Pour Crack Filler
Cold pour crack fillers are generally water based products which means you can easily just clean up with lots of clean water. In some cases, you might find a cold pour crack fill that is made from petroleum-based products and these will require a cleaning agent such as mineral spirits or toluene. All of the cold pour crack filler we sell are water based so cleanup is super easy.