Why does a high solid paint dry slower than its conventional counterpart?

The biggest reason high solid paint dries slower than its conventional counterpart has to do with its drying method. Conventional products dry in a physical way (evaporation of solvent) first, followed by cross-linking of the binder. After physical drying the paint film is more or less dry to the touch. To produce high solids, which still have good spraying conditions, binder products with lower viscosity and low molecular weight are used. The result is that the drying is more dependent on the chemical cross-linking, which is the slower process.

How can dry times be decreased?

The acceleration of drying is dependent on the chemistry of the specific coating that has been applied. Some products can be accelerated using a catalyst, others by temperature. Consult the technical data sheet and your ANAC representative to find a suitable method. Not all products are suitable for accelerating drying times and properties of the finished film may be affected.

How strictly do I need to adhere to mix ratios?

It is very important to follow the mix instructions as precisely as possible. The mix ratio for base, hardener, and activator components is determined by the chemistry of each component. Improper amounts of base or hardener will leave some of the resins un-reacted, which will create drying, curing, and performance problems. Too much or too little activator can increase or decrease dry time and affect appearance or production rates. It is also important to follow thinning recommendations. These recommendations are designed to ensure proper application, film build, and appearance of the coating system.

What effect does humidity have on paint application?

The effect during paint application is dependent on the amount of humidity in the air and the chemistry of the coating being used. All coatings are affected to some degree by extreme high or low humidity, but certain coating types, such as polyurethanes, are more sensitive to moisture than other chemistries.

High relative humidity will increase the cure rate of polyurethane topcoats, increasing the potential for film and appearance defects such as orange peel or micro-blistering. Extreme low relative humidity will lengthen the dry and cure times of polyurethane systems.

ANAC formulations are developed to be consistent in as large of range of application conditions as possible, but under very high or low humidity levels alternative reducers or hardeners may be recommended to provide the highest quality application and appearance.

Epoxy systems are much less susceptible to humidity variations; however, one particular concern is the combination of low temperature and high humidity. Some epoxy primers will "blush" in these conditions. Although not visibly detectable, the result is potential topcoat delamination. ANAC chemists understand the cause and take great care in developing and testing our epoxy systems to prevent blushing.