These products are considered hazardous waste.and can be brought to a Municipal Household Special Waste depot.
Paints and solvents (liquid paint, varnish, stains, thinner stripper, etc.) are among the more toxic products we have in our homes. Many paints contain heavy metals such as cadmium. Oil-based paints and paint thinners are made with solvents that evaporate easily, giving off harmful fumes. Leftover paint should never be thrown in the trash, poured on the ground, or into storm drains as it can contaminate groundwater and streams.
Ideas for leftover paint:
- Apply a second coat or use for touch-up.
- Stencil or sponge-paint walls or furniture.
- Mix latex paint together to use as a base coat (mix interior with interior; exterior with exterior).
- Give it away. Check with neighbors, friends, theater groups or community organizations to see if they could use it.
- Paint a fence, shed or your doghouse.
- List it on a classified ad or material exchange site
If you have one inch or less of leftover latex paint, dry it out by opening the can and letting it evaporate outdoors, away from children and pets. Dispose of the paint can with the lid off with your trash.
Reusable Building Materials Exchanges - such as Habitat for Humanity’s ReStore might accept used paint.
Paint brought into Household Hazardous Waste depots is often blended, or remanufactured into new product. Consider buying remanufactured or blended paint when it’s available.
Latex paints contain fewer toxic substances than oil-based paints, and do not require solvents for thinning and clean up. However they can still be hazardous. The best choice is organic paints, made entirely from plant materials. However, at present, these are difficult to find.
Buy only what you need. Here's a handy paint calculator for your next project https://www.benjaminmoore.com/en-ca/paint-calculator
In some areas Home Depot and Rona are now offering paint recycling. Eligible paints include latex, alkyd, enamel, metal and rust, stain, urethane, polyurethane, varnish and sealers for wood and concrete (empty cans are not accepted and those should be recycled dry with the lids off in your recycling box).