Ok I’ve done a search and I think I know what’s going on but looking for advice. Two things which I think tie to each other.
Q1. First I’m getting pimples in the hotcoat.
A. I’m mixing the resin too hot?
I use Suncure, but I mix in Cat as well. Try to get it to kick at around 10 minutes. When it starts to gel I expose to the sun. I might be leaving it out too long at first?
Q2. I get channels in the hotcoat, doesn’t seem to flow off the deck real good, or too much of it flows off?
A. Not using enough resin?
Because it seems to have too much flow off I think I’m trying to get it to kick to fast.
Ok quick update. I did a second hotcoat layer today, which is what made me bring this to the forum. It looks like I’m getting those pimples in the same place just the nose and tail. Any reason for just in those areas?
Pimples probably some dust or some other small particles landing on a wet hotcoat or brought up with rising wax. Is your room clean and not a lot of air moving around? Usually I put the side of my head close to the board to eyeball down the length - if I see tiny debris on a lam I compressed air blow off or vac the lam prior to hotcoat. You’re going to sand it, so small pimples usually no biggie. It’s the dimples/depressions/valleys in a hotcoat that can ruin your day. A smooth flat finish is only as good as the lowest spot
I will try to post pics later. But you might be on to something there bud. The room is clean, however there’s an overhead AC that I turn on. It could very easliy blow to the nose and tail of the board. Which is where I’m getting these pimples.
I use Suncure, but I mix in Cat as well. Try to get it to kick at around 10 minutes. When it starts to gel I expose to the sun. I might be leaving it out too long at first?
Why the sun?
I use UV Lam / S/A & MEKP as well,
Barry, dry lam, YUP or…
You didn’t blow it off with an oily air compressor?
Or your mix was whipped good, (air bubbles)
Ah, maybe brush pressure.
I do an acetone wash on the prior sanding coat to lose the wax if I don’t sand
Yup. Looks more like pinholess than zits. Air escaping through the hotcoat as the resin tries to settle in to the pinholes. The resin displaces trapped air, which has to go someplace.
Your other problem sounds like “slabbing”. It is caused by mixing too hot and too fast a kick. If you’re using catalyst, reduce the Sun exposure. Ten minute kick is a bit fast. Slow cures are stronger.
…sand the board; after that you ll see only tiny pinholes; clean very well the dust trapped there with air compressor and lay the gloss coat (that is for that)
Done
Just want to add that if you’re using UV powder or premix, you gotta “flash” it via sun or UV lightbulb for just a few seconds. Back to shade for 20-30 seconds then let sit in the sun till fully kicked. Sometimes I double flash. Don’t cook it in the hot sun for too long tho.The flash is so your wax can rise to the surface before full kick.Sometimes foam wants to breathe/gas out under high temps. Through the pin air most likely. If using mekp, let wax rise before setting in sun. When mixed in correct ratios and everything is timed right, a solar hotcoat is insanely easy to sand. Jam through the grits with little to no gum up even up to 600. Both those things could have happened but also looks like hot batch and a dirty brush.
I use cat and sun cure. So i get a little gel when take it out to cure. Didn’t want it to be “Dripping” as I moved it out. Next I’d like to build a UV Booth.
Brand New Brush for hot coat, although thats a topic in itself. I use those F’ing chip brushes that I’ve heard a lot use, but lose little hairs in the hotcoating.
No oily air compresser blow off I try to use a tape pull and drywall brush
My final stroke is very light pressure.
I’ve done other hotcoats the same way and no issues, even other resin pigments. So I’m guessing a lot to do with that Dry Lam thing. Thank you all for the advice, tips and help.
Cleaning the pinholes real well, you don’t want any white spots visible.
Mixing my hotcoat a little less hot, and adding a little bit of styrene in it, then pour a little bit of resin and pull it with a squeege where your pihnoles are, strong pressure to make sure the pinholes are filled with the resin,
Then take your brush, pour all the resin on the board while pushing the resin strong behind the pouring, tail to nose, nose to tail, then the usual cross pattern, then tail to nose and nose to tail with lighter pressure, walk away.
maybe try hotcoating on dropping temps. Dry lamination is most likely the culprit like Barry and Bill said but if the temp is rising while hotcoating it is also possible that your shaped blank was outgasing and actually blowing air up through the hotcoat. I like the colors you used in the lam. good luck
Thanks for all the advice. I gotta look more into the dry lam thing. I’ve never had it happen before, but the lam did kick sooner than I expected (I’m guessing my measurements were off). I noticed it after the laminate was done before I hotcoated, maybe I could of done something before the hotcoat to not have the issues now.
