Causes

1. Activator/hardener has been left out of two pack systems.
2. Too little or too much activator/hardener used.
3. No driers added to synthetics, (only for HMG mixing schemes).
4. Heavy application.
5. Drying environment is insufficient, (too humid, too cold, little or no air movement).
6. Insufficient flash off between coats.
7. Absorption of driers in Old synthetic products used after their shelf life.
8. Contaminated substrate, oil, grease, diesel/petrol, silicones.

Prevention

1. Make sure activator is used in two pack systems.
2. Always add the correct amount of hardener and make sure that the lid is replaced immediately with isocyanate hardeners after use.
3. Only apply at recommended film thicknesses.
4. Make sure the drying environment is suitable for the product being used. In some product HMG supply “wintermix hardeners” that are specially designed for colder conditions.
5. Make sure, (especially with synthetics) that there is good movement and circulation of air.
6. Make sure flash off time is adhered to between coats.
7. Do not use products after their recommended shelf life.
8. Make sure surfaces are clean and degreased before application.

Rectification

Make sure the object being painted/surface is in a warm, ventilated area.