SPI epoxy has no talc and is totally water proof.
Sorry I did not answer earlier but it was a first post and no explanation and I had no idea, why you were asking. I responded to your email, a minute a go and you have nothing to worry about.
For the rest of you, he applied two coats of epoxy and then it rained on it and he has some with spots.
This happens once a week in the boat industry, in South GA and FL, no problem at all, just scuff the whit spots off and paint or primer, in his case, could be a vinyl top installed and I said just leave as is.