“How Does Humidity Affect Paint?” and Other Common Spray Booth Questions

Temperature and humidity levels play a crucial role in the painting process. It’s necessary for a paint booth to be able to control both elements to help achieve a flawless finish. To understand the impact humidity has on paint, as well as other common questions, keep reading.

1. How Does Humidity Affect Paint?

Both types of paints used in refinishing (water-based and solvent-based) are negatively affected by humidity.

Water-Based: When using a water-based base coat, humidity will slow down its drying time. If the top coat goes on before the base coat is dry, it can compromise the durability of the paint as well as cause visual defects like dullness.
Solvent-Based: Most solvent-based products contain isocyanate, which is a chemical that helps solvents cure. Humidity can slow down or quicken drying times of solvents depending on the compounds in the mixture, which will diminish the longevity of the coating.

2. What Issues Can Humidity Cause?

  • Discoloration on the surface of the paint
  • Longer drying times due to high moisture levels in the air
  • Damaged paint finishes, such as lifting, not adhering properly, and visual defects, due to condensation
  • A change in the desired coating thickness

3. Are There Times Humidity is Needed?

There are times when humidity is needed within a paint booth. For example, some coatings require 30% humidity for application. This is especially crucial for shops located in dry climates to be aware of. Another reason humidity may be needed is for military and aerospace finishing. These industries use Chemical Agent Resistant Coatings (CARC) that can require a specific humidity range.

4. How Can Humidity Be Controlled Within a Paint Booth?

Whether you need to increase or decrease humidity within your paint booth, an air makeup unit (AMU) can help. A direct fire AMU uses a flame to heat the air within a paint booth, regardless of the exterior temperature. Due to its direct contact, the heat will burn off any moisture in the air and dissipate it into steam. However, more complex applications may require a paint booth with cooling and dehumidification hardware attachments to mitigate humidity levels.

5. How Can Accudraft Help My Painting Operations?

If you’re experiencing uncontrollable humidity levels within your paint booth, contact Accudraft. Our team can inspect your equipment to determine where the issue is coming from and if a part needs to be repaired or replaced. We can also install a completely new air makeup unit if necessary.