The Do’s and Don’ts of Applying Coatings in Cold Weather

28 Jul The Do’s and Don’ts of Applying Coatings in Cold Weather

Now that winter is fast approaching, many owners, engineers, architects, and others believe that all painting projects have to wait until the weather warms up.

Well, the short answer is, not so. With the right knowledge and materials, you can paint most surfaces in colder weather very successfully.

Allow me to share a brief story about the largest cooling tower basin in the City of Chicago.  The cooling tower basin was more than 100’ long and roughly 25’ wide.  We had bid on the project a year earlier, but it was given to the low bidder. The coating failed catastrophically. The building was a bank and would start to use the cooling tower as early as March.

We were tasked to do the work in February.  To make a long and highly technical story short, the job went off without a hitch.  We used and applied a modified urethane which cured down to 20F.

Many people understand it’s not a good idea to paint in cold weather, but most don’t understand why. So we’ll start by explaining the challenges and then the solutions.

Challenges:

• • The cold makes it difficult for people to move and work for long periods of time.

• • The cold typically changes the way that materials are applied, making paints thicker and harder to work with.

• • Applying the material on a cold surface will sometimes cause the paint to freeze, or thicken to the extent that it is difficult or impossible to apply.  

• • Moisture can freeze on the surface, causing serious application problems and premature coating failure.

• The paint may not properly cure, or stay soft for long periods of time.

Solutions:

• • Be sure it can’t wait. It will always be easier to paint in warmer weather.  

• • Consider the substrate you’re painting. Metallic or painted (non-porous) substrates will be easier to paint than wood and concrete (porous) substrates. Wood and concrete will be much more challenging to determine if the surface is damp.

• • Do some research. You may not have much luck going to Home Depot or a local store for paint. You may have to do some online research and call some of the larger paint companies and ask them if they have “cold” or “fast” cure paint systems. Many companies have, for example, epoxy paint systems that simply requires a different part “B” or an additive to make it a cold-cure system.  

• • Follow the paint documents closely. Read and understand the paint directions. Some cold-cure systems require an induction or “sweat in” time for proper performance. Induction time is the time a paint must sit after it’s mixed in order for the chemicals to begin interacting. Often, the induction time depends on the temperature. So, if it’s 10F, the induction time may be 12 minutes. But if the temperature is 25, it may be 3 minutes.  

• • Be sure the paint will dry. Some materials, like epoxies, will begin curing as the temperature warms up, and slow down or stop curing, as the temperature drops. Be sure you understand the type of material you’re using and don’t apply a material that will take two weeks to cure if it’s going to get rubbed or damaged in the meantime.

• • Be sure the surface is dry. This can be the most challenging problem because you may not be able to see if the surface is dry, particularly if it’s below 32F. A nice trick is to take an area that you want to paint, and safely warm it up. You can use your hand. Take a tissue, place it on the surface and place your hand over the tissue. The heat from your hand will cause any ice to melt, and you’ll see the dampness on the tissue.

Of course, you can always use supplemental heat to warm the area or asset you’re trying to paint. If you do this, be very, very careful if you’re working in a confined space and pay attention to the substrate temperature, not the air temperature. That is, if you’re painting a fire hydrant, and you build a tent around the hydrant. Don’t check the air temperature, check the temp of the steel.

Painting in cold weather is kind of like skipping dessert. It can be done, but it requires some special training and effort.