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April 1 - April 5, 2019

What causes amine blush in epoxy topcoats?

Selected Answers

From Josh Skinner of The Sherwin-Williams Company on April 6, 2019:
High humidity, condensation, low temperatures, improperly mixed coating, under-catalyzed OR over-catalyzed material, insufficient sweat-in time.

From Daniel Stahl of Blucoat LLC on April 4, 2019:
Epic Warren Brand! LOL

From Zenith Czora of Master Builders Solutions on April 4, 2019:
Amine blush or greasy film is a normal chemical reaction between amine-curing agents and carbon dioxide that forms a carbonate, appearing as a greasy film. The causes of amine blush  are high humidity, presence of excess carbon dioxide in the atmosphere and low curing temperatures. To avoid the occurrence of amine blush, check the environmental conditions and  apply the materials only when the temperature is a minimum of 10 C above dewpoint and rising and do not use propane heat in closed environments because it emits CO2.

From Warren Graves of Warren Graves Coating Consultant inc on April 3, 2019:
I would strongly recommend that people look up the article by George Mills in the November 2008 issue of Materials Performance. In the article Mr. Mills thoroughly explains the causes of this problem and some of the methods that can be followed to reduce the possible incidence of amine blushing. He points out that it is not only after applying a product that you can have the problem, but also when manufacturing the product or mixing the product you can create a problem leading to the reaction of the amine with carbon dioxide and moisture. I have also had a situation where a tank interior was heated with hot air, reducing the humidity in the tank to under 20% RH, but the tank floor was at about 50 F, so there was not enough moisture to cause any blushing, but there was the glossy amine exude on the surface that had to be removed.

From Warren Brand of Chicago Corrosion Group on April 2, 2019:
When it's told an embarrassing story?

From Marco Fabio Ramenzoni of ZINGA METALL BRASIL on April 1, 2019:
Incorrect component proportion mixing and consequent unreacted catalist reaction with CO² will form amine blush on the surface. Also, high humidity may cause amine blush.

From Mike DesPres of MMI Tank and Industrial Services on April 1, 2019:
High humidity and low temperature at the same time during cure right after the epoxy is applied causes amine blush.

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Tagged categories: Coating chemistry; Coating Materials; Epoxy

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