When resin cures in cold or humid conditions, it can develop a greasy or waxy condition on the surface known as amine blush. The term "amine blush" refers to the reaction between the amines in the hardener and moisture in the air.
Amine blush not only dulls resin's glossy finish but can also prevent additional resin coats from properly adhering if not removed.
https://www.artresin.com/blogs/artresin/amine-blush-what-is-it-and-how-to-prevent-it
