Add it to the paint (up to ⅔ of a gallon), allow it to harden, and throw it all in the trash. How to Dispose of Oil-Base Paint Oil- and alkyd-based paints are considered hazardous waste.

3. Use kitty litter or a commercial paint hardener For larger quantities of paint and absorbing the particles to dispose of paint water, you can use kitty litter or a commercial paint hardener to ...