I hope someone could help me with my "little" problem(sorry for the errors, english is not my mother language).

I just finished my mould that I made following the videos on the easy composit home page using the uni mould kit products. And I don't think I missed a step or did something wrong, but on one spot I got something strange. Something went wrong and I don't know what or why. It's like there's been some chimical reaction that gave this white layer so that the gel coat couldn't attach as it should.

To answer your questions, I followed the tutorial, but there was a crack on the surface, so I filled it with the yellow filling wax and gel coated it over. And I think you're right, with the exotherm kicking in the wax melted and reacted with the release agent and gel coat.