I just have a question about hot coats. I made a epoxy surfboard and did the top hot coat with epoxy and got a ton of fish eyes. I decided to try polyester resin on the bottom because I heard that some people do hot coats with polyester even if it is an epoxy board. I am somewhat experienced with making boards out of both polyester and epoxy but have never combined the two in any way. I have been thinking of my options and what I have come up with is either sand the epoxy hot coat down and do the top again with polyester or to sand the polyester hot coat completely off on the bottom and do it again with epoxy. What would be my best option?
I had this problem with my first board. Then I switched to Resin Research epoxy with additive F, and it really made a huge difference. If you glass with epoxy, it is recommended you hot coat with epoxy too. I always do. Then I gloss with poly.
Your mileage may vary, but this has worked well for me, as a beginner (7 boards).
As far as what to do with your board - I would sand it down to the weave, then hot coat with epoxy. Sand again, and gloss with poly.
thats what I am thinking of doing but i dont know if there any bad sides to doing that. i am thinking even if i sand it down to the weave it will still have a small amount of polyester resin in the weave and i dont know if that will affect the epoxy
I don't think so. You're going for a mechanical bond, not a chemical bond at this point. I would sand with 100 grit until you just barely hit weave, then stop. Make sure your hands are clean and dry when handling the board, dust it off, and re-hot coat.
I did a layer of 6 oz under a layer of 4oz on the top as well as the bottom so I think I will just sand the bottom and even if I expose the weave gettting all the polyester off, I wont sand through the 6 oz. I was just researching some more and I read that epoxy will chemically bond to polyester but polyester will only mechanically bond to epoxy. so as long as I get most of the polyester off i think i should be ok. should have just waited for more epoxy lol