I did not prepped the surface before putting the hot coat on. Straight onto the carbon which I vacuumed last week. I only sanded the rails, where there was a carbon overlap. Cleaned the board with a vacuum cleaner, compressed air and dust remove spray. 100% sure that the board was totally clean. The epoxy shop told me to sand the layer down a tiny bit and put another layer over, 'won't be a problem.' Not sure what to do now. I still have to do the top side, how should I prep it to prevent the same?
My feeling is a combination between the resin being super viscous, wrong prepped surface and painted areas with uneven surface.
It's a journey to find the right materials and methods. I was pretty happy with the results for a first carbon vacuum build so far, bummer to get the last step wrong.