Understanding how caulk dries helps ensure that you buy the right kind and use it correctly. There are three general types of caulk: acrylic latex, silicone and polyurethane. Because they are made of different material, the amount of time it takes for them to dry varies.
It takes about 24 hours for acrylic latex caulk to cure completely. Silicone and modified silicone caulk cures in 12 to 48 hours, and polyurethanes take between three and 10 days to cure completely. All of these curing times will vary slightly depending on the temperature and humidity in your area. Large joint depths, excessively cool and excessively humid conditions can lead to longer cure times.
Painting and Additional Information
There may be a difference between the time it takes for caulk to cure and the amount of time you must wait before painting it. The majority of acrylic latex caulking can be painted within two to four hours of application. However, clear acrylic latex caulks must cure for seven to 14 days before you can paint them. Consult the instructions on the caulk itself before purchasing and applying it, and remember that not all caulks can be painted.