I had six longboards to sand. After I laminated them and hot coated the decks, I used up all of my regular Sylmar resin and tapped into my new drum of “Sylmer Optibrite Resin”. Supposed to be cleaner and clearer…and more $$. So I hot coated the bottoms with it. Today I sanded all six boards. I noticed right away that the bottoms were WAY harder to sand than the tops were. It was very obvious and really pissing me off! All of the boards were glassed with “S” cloth except one which was glassed with 8oz Volan. The Volan board sanded much easier than the rest. What I’m trying to figure out is, is it the resin that made the sanding harder, or the resin combined with the “S” cloth. Has anyone else had experience with this type of situation?
Do you use S glass regularly?. S has thicker weave, and you could be sanding into the cloth.
Possibly your new batch cures quicker, and with full cure, it’s harder to sand. Since I mostly hand sanded, I’d usually hot in the AM, sand in the PM on the beach.
Opposite for gloss coats. They need to cure before rubbing, but I usually sureform the rail line when still kinda soft.
Thank you for responding. No…I don’t use “S” cloth too often, although that may change. I just hot coated and sanded like I always do. Hot coat the boards and sand no more than two days later. Never had a bit of problem before…not even with “S” cloth. You may be right about the resin curing faster or harder though. Next time I will try and sand sooner after the hot coat dries…see if it makes a difference. Only the “flats” were harder to sand. The rails were easy enough.
I remeber similar happening, and as LeeD said, the different batch of resin might be promoted differently, summer batch, winter batch etc.
‘Promoter’ was the name I know for the purple additive to make poly resin cure faster, actually harden faster. It does make the resin more brittle.
To speed up the occasinal shape-to-glass-to-sand-to-surf equation, I would promote the laminating resin, to then get the promoted hot coat on quickly.
The big problem was occasionally leaving it overnight to sand. Next morning it was rock hard and a pain in the arse to sand. And that was with a machine.
Future quick boards were sanded about an hour after gelling, which was more acceptable for my feeble sanding arms.
Sounds like I need to sand right away. How about the gloss? Same deal? Maybe this more expensive new resin wasn’t such a gook idea after all. What about just cutting back the mekp? (I use only Hi-Point 90) Leave it to me to find the most oscure problems with thing!
Gloss needs hard cure, lots of time.
Anything to slow your kick time is good for hotcoating, but why can’t you just sand the friggin boards sooner…change YOUR timing?
Well…If I had more arms and legs I probably could. But I am the chief cook and bottle washer here. My home shop has two down racks and plenty of off racks…but only me glassing, finning, sanding, polishing, pinlining, etc. Plus I have pending ding repairs all the time, an online bookstore, an acre and 31 chickens, a dog, four cats, wood to split, rock to haul, a shed to build, laundry to do, dinner to fix and a greenhouse full of hungry carnivorous plants. Quess I shoulda had some kids! Not complaining at all…just lots to do. Not worth training anyone because once they find out it’s hard work, their gone. You know how that goes. Besides, how would I advertise? “Help wanted. Poor working conditions and lousy pay!”