If you dont have enough money for thinner or the upside down trick doesnt work. Over by the paint section in Wal-Mart they sell this shit its called OOPS! its a multy purpose remover in an aerosol can. This shit is a cap saver and its cheaper than a can of Krylon. For best results use while you are bombing, use also after switching caps. If you feel or hear that your cap is clogging and the upside down trick doesnt work , which it doesnt always, pop those caps on a can of OOPS! & spray away. Just remember that the paint must be somewhat wet for it to work, it will NOT work if the paint is already dried in the cap. PEACE.