After a painting project is over, you may need to get rid of some unused latex paint. Even though this is water based paint, it is a hazardous waste, and you can't pour it down the drain or into a gutter. You can dispose of it safely though/
Step 1 - Open Your Paint Cans
The key step in disposing latex paint is allowing the paint to dry out. Thus the first step in the disposal process is opening up any cans of paint you want to get rid of. You want to protect yourself and your pets and family members from prolonged exposure to paint fumes, so make sure to place your freshly opened paint in an unoccupied area of your home, preferably an unfurnished basement or attic. An enclosed yard can also be a good spot for this. Should you decide to allow the paint to dry indoors, place your paint cans on top of a tarp or an expendable blanket in order to protect your floors and furnishing from any accidental spills.
Step 2 - Allow the Latex Paint to Dry
Give the latex paint ample time to dry. The amount of drying time largely depends upon how much paint is left in the cans. Your paint's drying time may also depend on its brand, so you may want to consult the manufacturer's website to determine how much time it will need.
TIP: Our expert painting advisor, Edward Kimble wants you to know, "It will actually take several weeks for even a half can of latex paint to harden completely."
You can speed up the drying process by adding sawdust or kitty litter to the paint. This additional material will help absorb the paint's moisture. If you really want to speed things up, try adding some special paint-hardening crystals. These additional measures are primarily recommended for paint cans that are more than halfway full.
Step 3 - Reattach the Tops of Your Paint Cans
Once your latex paint has sufficiently hardened, reattach the tops of your paint cans. Use a rubber mallet to firmly pound the tops back into place. After successfully reattaching your tops, you'll be ready to dispose of your latex paint.
Step 4 - Dispose of Your Dried Latex Paint
You can throw your newly hardened paint out with your regular trash. Given how heavy hardened paint tends to be, however, you may want to double-bag your discarded cans of paint.
TIP: Edward adds, "Oil base paints will also dry up and harden if left exposed to air."