Latex paint, commonly used as interior and exterior house paint, dries rather quickly compared to oil-based paints. While this may be desirable if you're looking forward to putting on that second coat of paint soon, it may work against you if you're whipping up custom-blended colors for detail work, such as a wall mural or faux finish. Latex additives, often referred to as conditioners, retarders or extenders, will extend the time it takes the paint to dry, giving you more time to create the exact desired look for your paint project.
Things You'll Need
Latex paint extender, conditioner or retarder (title varies depending on brand)
Paint stir sticks
Container with airtight lid
Read the paint conditioner instructions carefully, noting the recommended amount of conditioner compared to paint. Mix a small amount of conditioner and paint together in a disposable cup based on the conditioner's ratio recommendations. Stir with the stir stick.
Spread the conditioner/paint mixture on a scrap piece of cardboard, using a paintbrush to test for compatibility and drying time. Note how long it takes to dry.
Mix a larger quantity of conditioner and paint in a container with an airtight lid. Use the same ratio as you did with the test batch, or adjust it slightly if necessary, staying within the recommended conditioner to paint ratios. Stir with a stir stick. Replace the lids on the conditioner and the latex paint.
Paint your project with the conditioner/paint mixture. When you're finished, replace the lid of the mixture's container to save it for another painting session.
Many paint brands carry their own latex paint extenders. If you can't find one in your chosen brand, Flood and Coronado are popular brands.
Air temperature and humidity also affect paint's drying time. An exterior house paint project in direct sunlight on a warm, windy day will dry far more quickly than on a cool, overcast day. Paint during the paint manufacturer's recommended temperature range for the best results, often somewhere in the 60- to 80-degree Fahrenheit range.
Using a conditioner or extender also means you'll have to wait longer between coats of paint, and even if the paint feels dry to the touch, it may not be completely cured.