“At the end of a paint job, you’ll almost always have some leftover paint. Don’t dispose of it,” says Debbie Zimmer, director of communications and media relations at the Paint Quality Institute. Inevitably you’ll need to touch up a paint job, and you could have trouble matching the color at a later date if you don’t save the leftover paint.

Follow this expert advice to properly store open cans of paint. Do the job right, and your paint could last for years:

1. Never store paint where it will be subjected to subfreezing cold or extreme heat (more 100°F). Although most paints are formulated to withstand several freeze/thaw cycles, these conditions can ruin coatings by causing them to solidify
2. Always store the paint in its original container, with the label intact. This will help you properly identify the color and type of paint when you use it again
3. If key information is concealed by paint drippings, write down the brand, manufacturer’s code, color, gloss level, and type of paint on a strip of masking tape and affix it to the side of the can before you put it away. It’s also a good idea to include detailed information on where you used the paint, especially when similar colors were used throughout the house.
4. Clean wet paint from the groove on the rim with paper towels.
5. Cover the can opening with plastic wrap to help keep the container airtight.
6. On a metal can, replace the lid by using strong pressure to press it down into the groove lines. Don’t use a hammer to seal the can—you could damage the rim. Instead, use a rubber mallet, but not with too much force. If you have a plastic can with a screw-on lid, follow the first two steps, then apply the lid. If the leftover paint is an alkyd, or oil-based, product, place a piece of waxed paper directly onto the paint before sealing the can to prevent a film from forming as the paint sits.

Essential information: Read our March 2008 report on interior paints, including the latest information on one-coat finishing and details on volatile organic compounds (VOCs) in paint. And when the time comes to dispose of paint, find out the best ways to handle your old finishes.