120 Brushing Thinner is a general purpose thinner. Many paints when stored for some time before use will increase in viscosity and should be thinned. 120 Brushing Thinner evaporates at a moderate rate and is completely out of the paint film in several hours. Up to 10% is the normal recommended usage, some very hot and windy days may require more thinner. 120 Brushing Thinner is the recommended thinner for all Pettit solvent based topside enamels and varnishes as well as all antifouling paints except for Hydrocoat and Ultima SR-60.