If you work in the printing or building industries - more often than not – you’ll end up with some unused paint leftover.
Since some types of paint can be classified as hazardous waste, which means that they contain materials that can leak into the ground and cause physical injury to people, animals and the environment, you have to be careful when throwing it away.
Here's what you need to know, and to think about, before disposing of paint or paint thinners.
If you really want to throw out your tins of old paint, dry it out first.
Wet latex paint can be hazardous, so dry it up. If there's only a small amount of paint in the bottom of your can, leaving it out in the sun should do the trick. If there's a bit more than the sun can handle, you can add paint hardener, newspaper, sand or even cat litter to help soak up the paint and speed the drying process.
All of these options however, can still cause damage to the Environment.
If you feel bad just tossing your leftover paint, try to donate it ...
If you have a larger quantity of unused paint or sealed tins of old paints and thinners that you don’t need anymore, you can look into recycling it. An idea could be to call your local school to see if they have any big art projects coming up, or search for local companies that might accept extra paint.
.. or save it for later.
If sealed correctly, latex paint can last up to 10 years and oil-based paint up to 15 years. Next time you need a quick fix, you'll be glad you saved the leftovers. Environmental agencies recommend to keep paint in its original container (never in food containers) with the original label, adding the date you opened it.
To seal the can, place plastic wrap over the paint lid and hammer it down. Store in a cool, dry place away from sunlight and out of reach of children and pets. Once your paint is hard and lumpy, or if it has a particularly foul smell, it has probably gone bad and should be disposed.
What about paint thinners?
Paint thinner, or mineral spirits, is commonly used to clean oil-based paints and stains from brushes and tools. Most people dispose of the thinner after just one use, but that's wasteful and unnecessary.
It is illegal to dispose of solvents into open water, such as drains and gutters. They contain chemicals that can contaminate groundwater and endanger human health. They should be recycled for use in new solvents and paint products or safely disposed.
What happens when paint and thinners are recycled?
Paint and solvent recycling units use simple distillation. Excess paint is poured into the machine’s plastic liner and the lid is closed. The paint is heated until the solvent boils into a vapour and the paint residue is collected as a powder. The vapour is then cooled and the solvent drips into a collection tank to be reused. The paint solids retrieved during the recycling process can be reformulated into quality paint coatings.