Now is the time to remember this simple paint tip. With your exterior deck stain and house painting coming to a close, store all your leftover paint in their original containers upside down and inside. Before that final closure of the paint lid clean the paint out of the lip/rim of the gallon or qt, paper towel work fine. Then with all the excess paint cleaned off the can put the lid back on firmly, a rubber mallet reduces the dents caused from a hammer. If the lid is resealed without cleaning the rim first the paint with cement the lid on so future removal is tough. This storage method will stop all air infiltration eliminating the trapped air to dry the paint out over time. When you need to touch up or re coat you will have wet paint!