What is the Best Temperature to Paint Inside?

While our homes provide us with comfort and safety year round, they are unfortunately not impermeable strongholds, and the weather outside can affect painting conditions inside. Even inside temperature controlled homes, you should be mindful of extreme weather outdooors as this could have adverse effects on the results of your house painting projects.

What Is Paint Made Of?

One of the main concerns when dealing with the temperature in interior painting is how well the paint can adhere to and bond with the receiving surface. Paints are usually made of four main components, each with a particular purpose in the mixture:

-Pigments: the ground-up particles that are dispersed into the paint. This is what provides the paint’s color and coverage/hiding properties.

-Binder: ingredients that hold the pigments together and create a dry film on the painting surface. This is responsible for the paint adhesion, ease of cleaning, resistance to fading, and gloss retention. Binders also determine how the paint will harden as a result of either evaporating, cooling, or curing.

-Solvent: the liquid medium where the solids (pigments and binders) combine and allow them to be carried together from the paintbrush to the surface. The quantity of solids per volume will determine how much paint will remain on the surface after the liquids have evaporated.

-Additives: These extra ingredients can vary from brand to brand and have a multitude of purposes, from biocides that prevent bacteria from growing on the surface to thickening agents that provide more viscosity. These can also include ingredients that affect drying time and weather resistance.

All of these work in conjunction to form the uniformly textured liquid paint, but its proper adhesion and bonding to the surface are due in part to the evaporation of solvents and other liquids in the paint, which greatly depends on temperature and humidity.

How Does Temperature Affect Paint?

A factor that affects the performance and application of paint as much as the temperature is the level of humidity. No matter how arid the area you live in, there is always some humidity in the air.

The ideal humidity level is between 40 to 70 percent; if it is above this, the paint may not be capable of binding to the exterior surface, and slow down the drying time and entire process, especially if it is a days-long project. The paint will remain gunky and wet if the moisture in the air won’t allow the solvents to evaporate, and delay the curing time, while also keeping it from settling evenly on the surface.

Tip: While still allowing maximum drying time, if you’ve applied a coat the previous day, time your painting session so you can start several hours before the highest temperatures of the day.

When painting indoors, the temperature outside isn’t nearly as important as the humidity level and ventilation allowed, but it can still make a difference. The ideal range is between 50 to 90 degrees. If it’s too hot, the paint is forced to dry quickly, which can lead to cracking or can cause a film to form on the painted surface. If it is too cold, on the other hand, the paint will struggle to bond to the surface, and often remain a gunky mess.

Ventilation

A rule of thumb for interior painting is that you must have proper ventilation, preferably by opening as many windows as possible and using a box fan to push air out of the room. This is done to remove paint fumes and VOCs from the air that could cause minor irritations and/or long-term health issues. And if the resulting temperature and humidity are out of sorts it could either slow down or speed up the drying time undesirably. Choose a time frame that will remain between 50 to 90 degrees without rain or excess humidity for two to three days to ensure proper drying and curing times for your paint.

If you have ideas for an interior painting project you’d like to get started on and want a professional opinion, call the experts at CertaPro Painters® to schedule your free estimate and complimentary color selection consultation.