In this post we look at why high humidity can cause multiple paint defects during the application of paints and how to rectify them.
Humidity significantly impacts the application and curing of automotive clearcoat, as it affects the evaporation and reaction processes of the solvents and hardeners in the coating. Here’s how humidity can influence the clearcoat:
1. Slower or Uneven Drying
• Cause: High humidity introduces excess moisture into the air, which can mix with the solvents in the clearcoat.
• Effect: This slows down the evaporation of the solvents, leading to delayed or uneven drying.
2. Blushing or Cloudiness
• Cause: Moisture can become trapped in the clearcoat as it dries, especially if the temperature fluctuates or if the clearcoat is applied too heavy.
• Effect: This results in a milky or hazy appearance called “blushing.”
3. Poor Adhesion
• Cause: High humidity can cause condensation on the surface of the vehicle, making it difficult for the clearcoat to bond properly.
• Effect: The clearcoat may peel, crack, or chip prematurely.
4. Solvent Popping
• Cause: Excess moisture in the air can react with the solvents, creating gas bubbles that are trapped as the clearcoat cures.
• Effect: This results in small craters or imperfections in the finish.
5. Extended Cure Times
• Cause: Increased humidity can inhibit the chemical reaction of the hardeners in the clearcoat.
• Effect: The clearcoat takes longer to cure, which can delay further work and increase the risk of contamination.
Mitigating Humidity Effects
• Control Environment: Apply the clearcoat in a controlled environment with recommended humidity levels (typically below 60%).
• Monitor Temperature and Dew Point: Ensure the surface temperature of the car is above the dew point to prevent condensation.
• Thin Coats: Apply thinner, even coats to reduce the risk of moisture entrapment.
there are very good pieces of equipment that can help reduce moisture and change temperature when spraying too. Take a look at the below brands and what they offer.
WALCOM Thermidor technology
More information herehttps://walmec.com/en/products/thermodry-technology
SATA airline filtration system removing water and oil from the airlines that eventually lead to the spray gun.
more information here https://www.sata.com/en-eur/products/filter-technology/sata-filter-series-400/sata-filter-series-400
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