The Effect Of Temperature and Humidity on Paint

If an outdoor painting project is on the top of your to-do list, you might be policing the weather report to decide the perfect day to get it done. Yet if all you’re waiting for is a day without rain, you’re not giving enough attention to the weather report. That’s because temperature and humidity can have vital effects on paint as it’s drying, and zero of them are helpful. Even if there’s no rain in the projection, painting under circumstances in which temperatures and/or humidity are too high can mean all your hard work could wind up being for nothing. With the normal house painting project costing around $3,000, that’s an extravagant failure. If it’s a commercial or industrial project, you likely can multiply that sum several times over, depending on the extent of the project.

Whether the paint is oil-based, latex or acrylic, it is a liquid. That means moisture needs to be able to evaporate out of it at the correct rate for it to dry well. Temperature and humidity can wreak devastation on this process for many reasons, which ends in more than just having to wait longer for it to dry. Paint that dries too gradually or even too quickly it won’t adhere as well to the surface, with the result being unpleasant blemishes and premature flaking or peeling. 

For instance, painting when temperatures are too hot could mean that the top coat of paint dries and skins over, well before the layers underneath it have an opportunity to dry. That means the top layer of paint is in danger of actually sliding off the surface. At the very least, the dried top layer of paint will be dragged down by gravity and the paint will dry in waves of irregular thickness across the entire surface. This can cause blisters, cracking and peeling — even before the paint is dry. On the other hand, painting when temperatures are too low can generate other predicaments. Moisture in the paint may crystallize before it has a chance to evaporate, causing imperfections in the paint, for instance. Most oil-based paint needs to be applied at temperatures over 45 degrees Fahrenheit, while latex and acrylic paints must be applied at temperatures beyond 50 degrees Fahrenheit. 

Because the moisture level in paint is so relevant to drying properly, humidity can upset the balance and destroy a day’s labor. Most importantly, great humidity can re-introduce moisture into the paint as it dries, expanding the amount of time it takes for the paint to dry and increasing the risk of defects. Additionally, excess moisture in the air can be absorbed into wood surfaces and hurt the paint’s capacity to adhere to them. Humidity also has the potential to cause compounds in the paint to be filtered out of it, leaving patches of discoloration. 

There’s more to be worried about before beginning an exterior painting project than rain. Not taking into account extreme heat, cold or humidity can spell catastrophe for a painting project if you’re not informed of what they can do. Before you get started on your next painting project, review the accompanying guide and understand how temperature and humidity can become big issues for paint.