How to Store Paint So It Lasts (and Doesn't Dry Out)

That leftover half-gallon is worth keeping — matching touch-up paint later is a pain, and a sealed can stays good for years. The enemies are simple: air and temperature. Beat both and your paint will be ready when you need it.

Seal it airtight

Air is what skins and dries out paint. Before closing the can, wipe the rim groove clean (dried paint there stops the lid from seating). Lay a cloth or paper towel over the lid and tap it down firmly with a rubber mallet — going around the edge, not just the center. Hammering the bare lid bends it and ruins the seal. For extra insurance, lay a sheet of plastic wrap over the opening before pressing the lid on.

The upside-down trick

Once the lid is sealed tight, store the can upside down. The paint settles against the lid and forms its own airtight gasket, so the small amount of air in the can sits at the bottom instead of skinning the surface you'll use. (Only do this if you're confident the lid is fully sealed — otherwise you'll have a mess.)

Temperature matters

Paint is happiest in a stable, cool, dry spot — an interior closet or a basement shelf is ideal. Avoid the two extremes:

• Freezing ruins water-based (latex) paint — it can separate into a grainy, clumpy mess that no amount of stirring fixes. Keep it out of unheated garages and sheds in winter.
• Heat in an attic or hot garage thickens paint and shortens its life.

Label it

Write the color name, sheen, and the room it went in right on the can, plus the date. Six months from now you won't remember whether that gray was the hallway or the office. A piece of tape and a marker saves a lot of guessing.

Is it still good?

Open the can and check. Good paint stirs back to a smooth, uniform consistency. Toss it if it has a sour, rotten smell, if it's dried solid, or if latex paint has frozen and turned grainy and won't blend smooth again. A skin on top isn't fatal — peel it off, and if the paint underneath stirs smooth, it's fine.

How to dispose of it

Never pour paint down a drain. Let small amounts of latex dry out completely (add cat litter to speed it up) and toss the hardened remains with household trash where allowed. Oil-based paint is hazardous waste — take it to a local drop-off site.