How to Dispose of Paint Thinner

Paint thinner is considered a hazardous waste and must be disposed of in a manner that is safe for the environment and human health. It is basically a solvent that thins out oil based paint to the desired consistency, so that it can be applied easily and cleaned up. In many cases, after a painting project is done, you find that you have leftover paint thinner, and you may be unsure of the correct methods of disposal.

Never Dispose of Unused Paint Thinner like Ordinary Trash

Most cities have special methods of disposal for hazardous waste. If your area does not have a hazardous waste program, you must contact the local authorities on the preferred method for disposal. Never pour unused paint thinner down drains or in the regular trash. If it ends up in landfills or the water system, it will leech into our waterways, causing harm to the marine animals and polluting our water supply.
TIP: Painting professional Edward Kimble, author of Interior House Painting Blog, suggests, “Check with your local automotive repair and service shop or gas station. They have a tank for dirty, used oil and transmission and other types of fluids, and are actually paid when a reclamation company picks it up to refine into a usable oil. Most would welcome the paint thinner, as it would help fill their reservoir more quickly. That is how I get rid of all my used paint thinner safely and environmentally pure.”

Purchase Only the Required Amount

If you rarely use paint thinner, purchase small amounts as and when required. Try to use up all the paint thinner by applying additional coats of paint or by painting some small objects that need retouching. Never buy large quantities that you will not be using. If you have some unused paint thinner remaining, you can also give it to a friend or neighbor who plans to undertake a painting project.

Reuse Excess Paint Thinner

You could also store used paint thinner and reuse it in your next painting project. Wear gloves to protect your hands. Pour the used paint thinner in a glass bottle or container and close the lid tightly. To prevent someone else from mistaking the paint thinner for something else, label it appropriately. After a few months, the paint particles will settle to the bottom and leave clear paint thinner on the top. You can pour out this paint thinner and use it in your next painting project. Avoid pouring the paint thinner in a container that was previously used to hold edible substances.

Dispose of the Paint Sludge

After you recover the clear paint thinner, you will be left with some colored sludge in the bottom of the container. This sludge must be disposed of in accordance with the hazardous waste disposal guidelines in your area. Call the disposal helpline and arrange for drop-off or pickup of the waste matter. If you do not have arrangements for hazardous waste disposal in your area, you can leave the sludge open in a well ventilated area. It will dry completely after some time. You can dispose of this dry remnant in the garbage can. You must, however, contact your local authorities and ensure that this is acceptable. You could also try and accelerate the drying process by adding sand or cat litter to the sludge. Dry waste is easier and environmentally better to dispose of than wet waste.

Edward Kimble, professional painter and author of Interior House Painting Blog, contributed to this article.