Did my first hot coat this weekend. The bottom coat went good, but the deck coat did something weird in a few spots - the hot coat “pulled apart” or separated on the rails in some spots. I didn’t notice until after the resin started to kick so I couldn’t brush back over them. I am 100% sure that these few areas were covered initially, but the resin seemed to have just kind of pulled apart in a few areas. It didn’t run or drip, it was almost like the resin was repelled from these spots. Any idea what would’ve caused that? Also, I assume that I should just hit these areas again now that the coat is dry. Any thoughts?
Finger grease… never eat a pizza and hot coat at the same time… Before hot coating (or glossing) always make sure you wipe down things really well with acetone (for poly) or denatured alcohol (for epoxy). If you don’t, the oils will repel the resin and you end up with exactly what you’re talking about.
Thanks, Chachi. I wiped down the board with a damp rag just to make sure I had all dust off, but I didn’t know to do it with acetone. So I guess I’ll clean off those areas then coat them again. That’s about lesson #10 on this first board of mine.
Jim, Hold the phone! Wiping your lam coat with acetone before you hotcoat is not a good idea. The lam is already sticky, and acetone will soften the surface even more, as it starts to dissolve the resin. If you have a dirty area, like a fingerprint or hand print, concentrate on that area with a little acetone, but be careful that you don’t overdo it.
To avoid the situation all together, only handle the lam-coated board with wax paper, or auto tape-off paper. Don’t touch the lam resin with your hands. Doug
So what is “a little acetone”? Just a quick, light wipe of the affected area will be OK and will do the job? Then what about the hot coat prior to gloss? Besides trying not to handle it with my bare hands, should I wipe the sanded hot coat with something before glossing?
After you hotcoat, you can take some lquid dishwashing detergent and make a mild sloution with warm water to wipe the board down with. Rinde thoroughly and your ready to gloss!
How fast, or slow, did you “kick off” the hot coat resin? One problem I encountered was catalysing to slow and garvity started to pull the resin apart in the same manner you mentioned. Might not be your problem, but just a thought and the damage is not irreparable.
I used UV resin with 4% surfacing agent per the guys at Fiberglass Hawaii and instead of putting it in direct sunlight to cure, I did it the “slow method” by keeping it in the shade (in my garage with the doors and one window open (no direct light hit the board though). It still went pretty dern fast though. It definitely didn’t look like a gravity slump, flow, drip or sag - just a separation. The oily spot repel call was right on. I think the spots are where I was holding the board while I surformed off some drips and edges of laps.