When you're doing a painting project, it's nearly always best to follow the directions and recommendations printed on the label. However, labels can't cover everything. Your specific environmental conditions -- such as very hot or cold weather, dryness or humidity -- can greatly influence drying times between paint coats.
Latex paint is water-based and, in general, the fastest drying of all interior paint formulations. It comes in various finishes, from flat to satin and high gloss, but all require only about one hour to dry to the touch under ideal conditions. However, you should wait at least four hours between coats to ensure that the paint is fully cured.
Note that while the word latex generally refers to rubber, latex-based paints do not, in fact, contain latex, but acrylics or vinyl. Therefore, according to the American Coatings Association, latex-based paints do not pose a threat to those with latex allergies.
Alkyd paints contain alkyd resins -- a complex chemical compound composed of alcohol and fatty acids -- thus the original name alcid, which became alkyd. These resins are modified with oil to produce a coating material, and therefore have drying times similar to oil-based paints. Alkyds generally require six to eight hours to dry to the touch, but second coats should not be applied for at least 16 hours.
Like alkyds, oil-based enamels require six to eight hours to dry to the touch, and you should wait 16 hours or more between coats.
Shellac is sometimes used in faux and special painting techniques. It's an organic coating made from the ground bodies of the lac beetle mixed with alcohol. As an alcohol-based coating, it dries to the touch within minutes and takes only about 20 minutes to be ready for a second coat. However, for a thoroughly hard surface, shellac needs several days before you attempt finish techniques such as rubbing.
Conditions Affecting Drying Time
Heat or Cold
High temperatures speed evaporation and contribute to faster drying time. However, too much heat may cause surface drying before the paint solvent beneath the surface has completely evaporated -- leading to blisters or improper curing. Do not paint when the area is above the recommended temperature range for your product.
Cold temperatures may have a reverse effect. The same latex-based paint that requires four hours dry time at 75 degrees Fahrenheit may take six hours or more at 50 degrees. Alkyds and oil-based enamels that take 16 hours to dry at 75 degrees could take as long as 48 hours to dry at 50 degrees. You can use heaters or fans to speed drying by increasing the evaporation rate in cold areas, but avoid painting when it's below 40 degrees Fahrenheit .
Humidity is merely the amount of water vapor in the air. The higher the humidity, the more water in the air. When the level of moisture in the air gets very high it's difficult for solvents to evaporate, which extends paint drying times. The industry standard -- perfect temperature/humidity levels for painting -- is 77degrees Fahrenheit and 50 percent relative humidity.