I would appreciate some advice regarding the hot coat. I am using a cheap, poliester resin from a local supplier and it seems to work fine for the laminate coat. I use the same resin and catalyst for the hot coat and althopugh the finish is ok it seems to be porous. Ifteh boards are left out over damp grass at night the board looks milky, cloudy and it is as if the moisture has absorbed into the resin. It does disappear but it worries me as it suggests the board is not “sealed”. I don’t think there is a problem with any water getting through to the foam, it just seems to be the very surface layer. Recently I laid a board down on some newspaper and after an hour or so the print seemed to have been absorbed into the board??
I am using the same resin and catalyst for the hot coat as I do for the laminate coat. Am I missing something? Is there something else that should be added to the hot coar resin to make it harder and less “porous”?
You shouldn’t be using the same resin for laminating and hot coats. That is, you can use lam resin for a HC as long as you’ve added surfacing agent. So, it sounds to me like you are using lam resin for your hot coat without the additive. Lam resin will turn milky on the surface when it comes in contact with moisture. Hot coat resin should not.
Conversely, using lam resin for a hot coat without the additive is just plain wrong. Since, without the additive it isn’t really a “hot coat”. Good luck sanding that.
You are doing everything wrong that could possibly be done, go back and do some reading in the archives. I'm wondering if your post is a friggin'n yoke o' what??