What is Amine Blush?
Amine blush is a chemical reaction that can occur when environmental conditions are favorable for the amine curing agent on the surface of the coating to react with carbon dioxide and moisture in the atmosphere to form a carbamate. Or in more practical terms, the reaction some epoxy resin systems have with the air that causes a waxy finish or film on their cured surface.
When working with epoxy, all surfaces must be clean of any residue. Wiping down the surface with solvents such as acetone or lacquer thinner.
This is an image of a standard 5:1 epoxy system and the amount of blush left on the surface after it was allowed to cure in the presence of regular moisture in the air.
MAS 2:1 Non-Bushing system does not blush. You can continue laminating before the product has completely cured instead of waiting to wash and sand before the next coat. This means, non-blushing epoxy requires no messy wash downs in between coats. Therefore, you can re-coat the same day and save at least twice the time.
Traditional Marine Epoxy
MAS Traditional Marine Epoxy does blush when fully cured. The surface will have an oily, greasy feeling to it. Epoxy bonding surfaces must be free of any contaminants such as grease, oil, wax or mold release. Therefore, the surface must be wiped down with lacquer thinner, acetone or appropriate solvents.
The Advantages of Non-Blushing Epoxy
With a non-blushing resin you do not have to worry about wiping clean your laminate or coating between layers of epoxy. If blush is not cleaned properly it can affect the adhesion of your epoxy to the next layer. Blushing systems are not typically as clear as their non-blushing counterparts as well.
Why would someone use a blushing resin then? There could be a few reasons. First, they could be used to that type of system and not know about the benefits of a non-blushing resin. Or, they may be interested in saving money on their epoxy. If this is the case it is definitely okay to use a 5:1 system and be aware of the nuances of cleaning between coats. But, if you’re looking for a very user-friendly and beautiful structural finish with no cleaning necessary, go the non-blushing route!