The cloudy coating in the lower left of the picture is the blush caused by West System 206 hardener. The third blushing patch down on the test panel is East System.

Blush is a waxy coating of amine carbonate which is 'almost' water soluble. It is caused by highly reactive epoxy hardeners with carbon dioxide and H2O vapor. You can get rid of it with water and some abrasive scrubbing which will prepare the surface for more coats of epoxy. I say it is 'almost' water soluble because it will require some elbow grease. It is similar to 'soap film' on batroom tiles and we all know how much fun it is to scrub those
The best way to reduce the risk of blushing is to use the slower hardeners or incorporating only a small percentage of the the fast hardener in the total hardener mix.
The link below shows the blushing behavior of various brands of epoxies.

Vaclav