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5 Tips for When Your Car Paint Won’t Dry

Every technician has experienced a sticky or tacky finish in their career. This typically happens when the paint hasn’t dried properly—not to mention the number of other defects that are likely to occur. While it’s best practice to wait until coats are fully cured or at least beyond their drying time, there are a few other factors that could affect the painting process. Here are a few reasons (and fixes) if your car paint won’t dry.

Common Causes of Paint Not Drying

  • It was applied too thick
  • Too many coats were applied
  • There was high humidity during the painting process
  • It was too hot or cold in the paint booth
  • The recommended coating drying time was not followed

How to Fix Paint From Not Drying

  1. Follow the Technical Data Sheet: While it’s easy to think every type of coating has similar rules, that’s not the case. In fact, every manufacturer has a different technical data sheet (TDS) for every coating. This provides valuable information such as the recommended number of coats and drying time between coats.
  2. Use an Air Makeup Unit to Control Humidity: An air makeup unit (AMU) can help control a booth’s inside humidity level. While ridding humidity can help when painting with solvent-based coatings, you’re better off controlling humidity levels when using waterborne paints.
  3. Use a Heating System to Control Temperature: A heating system can help control a booth’s inside temperature. Ideally, a booth should sit at 70 degrees Fahrenheit, for both water and solvent-based paints. If your booth is not equipped with a heating system, handheld, portable, or overhead systems are available.
  4. Try Hardeners: Depending if you need your paint to dry faster or if you need to slow down its drying between coatings, hardeners can help. As always, read their technical data sheet before using an additive product alongside your coating.
  5. Adjust Flash Cycle Settings: Flash cycle settings ramp up air speed and introduce heat to the booth to help drying times. Accudraft allows you to control flash settings to help ensure the paint is dry by the time you’re ready to apply to next coating (according to the TDS, of course).

Humidity vs. Temperature

While waterborne paints are more commonly used today, understanding how humidity and temperature affect water and solvent paints are important.

Heat burns out moisture in the air, making it a favorable environment for solvent paints to dry. However, little to no humidity can also make it difficult to apply water paints (after all… it is water). Sometimes a little humidity makes it easy to apply water paint, but then makes it harder to dry because of the moisture, therefore making the already wet paint remain wet. For this reason, it’s valuable to be able to control humidity within a paint booth to increase and decrease levels depending on where you are in the painting process.

Temperature plays a huge role for both solvent and water paints. For solvent paints, too hot of a temperature will dry the coating too fast and cause wrinkles or cracking. A technician may also think since the coating is dry on the surface level, they can apply the next layer causing it to become too thick. The problem here being the tech has now stacked material on top of material that isn’t completely cured. This can result in delamination issues down the road, solvent pop, and other issues.

Too cold of a temperature will prevent chemical cross linking, which is important for the effectiveness between coatings, primers, and hardeners. Regarding waterborne paints, water dries by dehydrating and evaporating water out of the air, which is why low humidity and higher temperatures are extremely effective between coatings.

Pro-tip: Install the Accudraft Xcelerator, which accelerates waterborne dry times in half.

Finding the Right Paint Booth Setup

The Accudraft sales team can help you determine your goals. For example, is your biggest issue output or time? Would you like to expand your vehicle mix or better improve your current floors production? Are you looking to upgrade an existing finishing system or install a new setup? Call us to talk through these key factors and more! We can discuss your shop needs and help pair you with the right finishing system set up.

Call 1-800-524-0340 or contact us online.