Paint Booth Temperature Settings – A Practical Guide

We were recently asked to give advice on recommended temperatures for painting in a spray booth, and in general, talk about just how important temperature control really is during the paint process. Since the answer varies widely based on what coating you’re using and many other factors, there isn’t a ‘magic bullet’ for this problem.

However, we received some excellent general guidelines from two of our GFS experts that can give you an idea on what you should be looking at for average temperature settings for your paint booth.

First, let’s take a look at an Auto Refinish scenario…

Brandon Lowder (GFS Distributor Development/Strategic Accounts Manager, Auto Refinish), suggests the following:

A paint booth must be a minimum of 55 degrees for any automotive paint with a catalyst to dry. All automotive paint companies base the time it takes to flash, cure, recoat, etc. on 70 degrees and 50% RH (relative humidity). There is a standard basic rule in the automotive industry that for every 15 degrees above 70 degrees, the coating will cure about twice as fast. This rule works the other way around as well; for every 15 degrees below 70 degrees, the coating will take about twice as long to cure.

Of course, this is only true down to 55 degrees, where the catalyst becomes dormant and does not crosslink. Once the catalyst is dormant, it will never crosslink properly. Since much of the country is warmer than 70 degrees for at least some of the year, paint companies have different catalyst and reducers to compensate for the rapid increase in cure times while applying the coating.

Using the rule of 15, it is easier to address why temperature control is so important. If you are spraying a product that takes 30 minutes at 70 degrees to flash before it can be coated with the next step, a shop could effectively cut that time in half (to about 15 minutes) if they have the ability to raise the temperature in the booth to 85 degrees. GFS auto refinish booths with LOGIC control panels automatically do this with smart flash modes. Our AXIOM control panels achieve temperature control with the manual flash mode.

Clear coats are based differently today since there are so many new products available, but the product works in a similar way. If a clear coat would cure in 3 hours at 70 degrees, it would be possible to cure it in 15 minutes at 140 degrees.

As you can see, heat exponentially increases the paint shop throughput. More than twice the amount of work can be put through a heated booth vs. a non-heated booth.

If you have a non-heated booth, you also have to keep in mind the amount of heated air that is exhausted from a heated building. This is especially important during winter months in colder states. For example, say you’re working out of a shop in Green Bay, Wisconsin in January. The outside temperature is 25 degrees. The building is 10,000 sq./ft. with 15’ sidewalls. Therefore, the building would have 150,000 cubic feet of heated air in it. If the shop had a non-heated paint booth that moved 12,000 CFM (standard auto booth), the booth would have exhausted all of the heated air in the building in 12 ½ minutes, requiring the building heat system to replace it. Most buildings will not have the capacity to do this so the temperature in the building and booth will not be able to maintain a constant temperature above 70 degrees.

Next, we’ll talk about temperature settings in Industrial applications… 

Jim Husby (GFS Territory Manager, Industrial), suggests the following: 

The average temperature it takes to cure paint is between 65 and 70 degrees F. Determining the right temperature for each paint job is a more complicated process though.

First, you want to look at what kind of coating you are using. No two coatings are the same; and the list of coating types goes on and on. Also, a coating type from one paint manufacturer is not necessarily the same as a coating type from another paint manufacturer. 

Next, you should consider what you are painting. The size of the object will affect how long it takes to dry and the appropriate temperature setting required. For example, a massive C-17 aircraft will take much longer to dry than a small part would.

The last factor you should consider when determining the appropriate temperature to set your paint booth at is humidity. As we know, a temperature in one location is not identical to that same temperature in another location. It will take longer to dry paint on the same object with the same coating on a humid, 70-degree day in Florida than on a dry, 70-degree day in Arizona.
Because of these factors, it is impossible for us to identify just one “recommended temperature setting” for all customers. Your best bet is to check with the paint manufacturer, as they will be able to tell you exactly what temperature your booth should be set at to properly dry and cure your coating.

4 thoughts on “Paint Booth Temperature Settings – A Practical Guide

  1. Don Putney

    The higher the temperature the slower the air speed reducing the effectiveness of the envelope of air around the vehicle. It is best to spray at 68 to 78 degrees F. to reduce the risk of contamination in your paint jobs.

    Reply
  2. Brandon

    Hi I am painting a jetski in my garage . The outside air temp is 95 and I try to paint when it get around 80-85 degrees. My problem is the paint never seems to dry it just stays tacky . Please can you tell me what I can do so I can mask off and paint another color. Thank you for you time .
    Brandon

    Reply
    1. Global Finishing Solutions Post author

      Hi Brandon,

      While there are many factors unknown to make a truly accurate assessment, based on the information at hand our experts had these comments:

      “There are several issues that would cause this and none of them would be specifically related to the air temperature in this particular case. We would need to know what kind of paint is being used. If it is a non-catalyzed paint (meaning it does not require a hardener to dry or it comes from a spray can) then then it possibly has been applied too thick, or there was not adequate drying time between coats. If there is relatively no shine or poor gloss to the paint, it will need to be stripped off and repainted. Without a proper high-temperature bake, it’s unlikely that it will ever dry and be solid enough for durability let alone painting other colors on top of it.

      If it was a catalyzed product (meaning a hardener was needed) then it’s highly probable that the product was mixed incorrectly. Either too much or not enough hardener was mixed into the paint.

      One thing that could be attempted is to set the jet ski out in the sun on a hot, breezy day for a long period of time and it may help to dry the coating but it is fairly likely that it will never have the strength to allow for masking or other coatings to be sprayed on top of it.”

      Reply

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