Dry Spray (Spray Dusting) Issue

Problem Description:

Dry spray occurs when paint emitted from the spray gun dries too quickly and adheres to the surface in a rough, textured manner. Although this issue may not always be visually obvious, it can be felt by touch. It typically arises from premature drying of the paint or improper application techniques.

Possible Causes:

• Excessively High Temperature: Elevated temperatures in the application environment cause the paint to dry rapidly as it exits the spray gun, resulting in a rough surface.
• Fast-Drying Paints: Paint formulations containing very fast-evaporating solvents can lead to dry spray.
• Incorrect Spray Gun Distance: Improper adjustment of the spray gun-to-surface distance prevents the paint from distributing evenly, promoting dry spray formation.

Solutions and Precautions:

• Maintain Ideal Temperature and Humidity: Regulate environmental temperature and humidity to optimal levels for painting. Recommended conditions are approximately 20°C (68°F) and 45-60% relative humidity.
• Select Suitable Paints: Use paints with slower drying and controlled curing properties.
• Adjust Air Pressure: Set the spray gun air pressure to the ideal range, typically between 2 to 3 bar, avoiding excessive pressure.
• Control Paint Viscosity: Maintain the correct paint viscosity, targeting 13-16 seconds on a Din-Cup4.
• Choose Appropriate Thinners: For solvent-based paints, opt for slower-evaporating thinners.
• Maintain Proper Spray Gun Distance: Keep the spray gun 15-25 cm away from the surface to ensure even paint distribution.

Dry spray can be prevented by controlling environmental conditions, selecting appropriate materials, and applying correct spraying techniques.