It’s recommended to apply paint at a room temperature between 50-95 degrees F. So, does that mean that temperature affects drying time?
The temperature affects the drying time of the paint because it determines the evaporation rate of the paint solvent.
For paint to dry, the solvent (or moisture) in the paint must evaporate and evaporation occurs through heat. So, when the temperature is high, the evaporation rate is higher, and paint dries faster.
But, when the temperature is low, the paint will take longer to dry. This is how the temperature affects the dry time of the paint.
Paint Dries Faster in Hot Temperatures
Paint dries faster in hot temperatures than in cold temperatures. That’s because the rate of evaporation occurs faster when the temperature is hot. The faster the solvent in the paint evaporates, the faster paint dries.
Paint won’t dry fast in cold weather because the drying conditions are not ideal. The cold temperature will slow down the paint’s evaporating rate, causing it to remain wet for hours.
How Does Paint Dry?
To understand how paint dries based on the temperature, let’s take a brief detour to understand the formula of paints. The paint formula contains pigments, additives, and binders. These ingredients are dissolved in a solvent to keep them from solidifying in the paint container.
When the paint is applied, the particles are applied with the solvent (water or oil). For the paint to dry, the solvent needs to be evaporated; this evaporation can only occur when there is heat.
The heat boils the solvent turning it into gas so it evaporates and the paint can dry. Also, when there is heat, the air current moves faster. The improved air current causes the paint to dry and cure faster. This is why paints generally dry faster in hot temperatures.
When the weather is cold, paint won’t get enough heat to warm up the solvent to the point of evaporation. Also, the air current moves slower when the weather is cold because the air contains more moisture (or high humidity) so your paint will dry slower in cold temperatures.
Things That Affect Drying Time Of Paint
Asides from the ambient temperature, here are other factors that affect the dry time of your paint:
Humidity relates to the level of moisture in the atmosphere. When the humidity level is high, more water is in the atmosphere. This happens during and after rainfall. Since there is increased water in the atmosphere, the air current is slowed down and the temperature will be cooler. This will cause your paint to dry slower.
The paint can turn tacky, in extreme cases. However, the paint will dry if the humidity is at the right level. You should apply paint when humidity is between 40-50%. You can test the humidity levels with a hygrometer, and reduce it with a dehumidifier.
The Number of Coats
The number of paint coats determines the dry time of the paint. The more paint coats you apply, the more solvent there is and the thicker the paint is, so the paint dries slower. It’s recommended to apply only 2 coats of paint (4 coats is the maximum).
The level of prep work and how ready the surface determines the paint’s dry time. Before painting, you must wipe, clean, and sand the surface.
Sometimes, you’ll also need a primer coat before applying the paint. If you don’t prime or wipe the surface before applying the paint, it will not dry fast.
Temperature Affects Paint Curing
Temperature affects paint curing time, but it’s not the only factor. The air current around the paint also affects its curing process. Both, the ambient temperature and air current around the paint determine its curing time.
For paint to cure, the paint particles and pigments in the paint must solidify and harden. This occurs as the paint chemicals react with the oxygen in the atmosphere to become tightly packed, this process is known as oxidization.
The amount of air that the paint is exposed to after it dries determines how long it takes for the paint to cure. If the paintwork was done near the window, it will cure faster because it will be exposed to a higher air current.
I know what you are thinking –- “Since air determines the curing process, how does temperature now affect paint curing?”
The air current is determined by temperature. When the temperature is cold, the air current will move slower, this will cause the paint to cure slowly.
When the temperature is hot or warm, the air current moves freely and faster around the paint coat. So, while air directly affects how your paint cures, the temperature indirectly affects it because it determines the air current or airflow.
Best Temperature For Painting
For outdoor paint jobs, the ideal temperature is between 65 – 85 degrees F during the day, and above 32 degrees F at night.
If the temperature gets too high, the paint will crack off because it will dry too fast. Due to higher temperatures, the solvent evaporates faster than it should, and paint particles will be forced to bond instead of bonding naturally. The forced bond wouldn’t be strong and begin to crack after a few days causing the paint finish to fall off.
Also, you don’t want the temperature to be too low, especially at night. If the temperature gets too low outdoors, your paint will not dry.
For indoor painting projects, the ideal temperature is between 50-85 degrees F during the day, and 32 degrees Fahrenheit at night.
You don’t need the temperature to be very hot indoors. Paint will still dry if the indoor temperature is 50 degrees Fahrenheit. This is because the warmth indoors is trapped and will circulate inside longer than outdoors.
This is why you feel warm inside even without turning on the heater. The walls keep the heat trapped and this helps the paint dry faster.
What Happens If You Paint When It’s Too Cold?
If you paint when the temperature is too cold, the paint won’t stick and dry properly. This is caused by the slow rate of evaporation in the cold temperature.
Since your paint isn’t sticking or drying well, it will begin to shrink on the surface. When your paint starts to shrink, lines and wrinkles will form on the paint coat. The lines will get swollen over time as the paint gets exposed to dry air.
In the early stages, you can fix the wrinkled paint if you touch it up with a fresh coat. If you don’t fix it, the cold will turn paint tacky and start to smell depending on the type of paint that you apply. Oil-based paints begin to smell foul after a few days of exposure to cold temperatures.
What Happens If You Paint When It’s Too Hot?
If you apply paint when the temperature is too hot, the paint will dry too fast. This is because the evaporation rate will increase, causing the paint to dry too fast. When this happens, the paint will become weak and it takes little impact to dent or cause the finish to crack.
For paint to be strong and durable, the paint particles have to bond and solidify naturally. When the particles bond together, the paint will become strong and can handle traffic and furniture weight. This solidification between the paint particles occurs a few minutes after the paint has dried.
If the temperature is too hot, the increased heat will cause the paint particles to dry up and bond prematurely. It would be a forced bond and this bond between the particles will be weak. If the paint dries too fast, it will crack when you walk or put heavy furniture over it.
If the paint dries too fast, it won’t give the right color shade. That’s because the paint pigments will dry in the paint instead of setting across the surface. Having your paint dry too fast doesn’t give the best results so ensure not to paint when it’s too hot.
In summary, temperature affects your paint’s drying and curing because it determines the rate of evaporation and movement of air around the paint. It’s better to apply paint when the weather is warm than when it is cold.
Test the humidity levels and check other factors that affect the paint’s drying time before applying it. Finally, follow the manufacturer’s instructions regarding the paint’s dry time and drying conditions.