Holy cow, my first epoxy glassing ends up with a truck load of pukas or dimples all over the gloss coat, the pinline color got smeared into the clear when sanding the hot coat to prepare for the gloss coat. AND after glossing, shiny patches appared along the pin line. Like it reacted to the water based acrylic.
I prepped for gloss by sanding, a wipe with denatured alcohol and a swipe with a strip of masking tape to pick up any dust.
I can sand off all the gloss and do it again, but what went wrong so it won’t happen again?
Damn. Nothing that I can point at and say “that’s it!”. The slow hardener did not help you, though. It gives the epoxy time to develop the dimples/craters. The defects are depressions in the surface, not little high points, right?
OK. Here’s what I think. The acrylic going all over the board from the sanding and DNA did not necessarily help. I have had bad experiences with an acrylic, the Aervoe spray acrylic I used to seal paint with. Temperature was fine. The reason I wanted to know wabout the sandpaper was that if you are using the ‘improved’ type papers with a stearated coating (like Norton 3X), it can cause problems.
Is there any source of oil or silicone anywhere in the room (like an oil-lube comrpessor running nearby)?
These defects are usually caused by either particulates (dust) or oily/silicone type contaminants.
One more question: Did you see the dimples form as soon as you brshed it on, or did it happen after the walkout? If it was long after the walkout, you may need to use a faster hardener. If it happened right away, it was a contamination/compatibility issue.
Either way, When you notice this is happening, get a squeegee and get that stuff off of there. The squeegee will still leave a very thin layer of epoxy on the board, and sanding this the next day with 150 or so will let another coat flow on great, as epoxy loves to stick to itself if it is fresh (less than 24 hrs) and roughened up a little…
The squeegee beats the hell out of the sanding job you’ve got ahead…
Don’t use DNA next time, just sand it, dust it off, wipe it with a paper towel. Don’t touch it with you oily grimey hands, use paper towels to touch. You probably had body lotion on you hands, then you started to get all lovey and feel up the surfboard. Less contamination the better…nothing better than a properly sanded surface. A sanded surface is a clean surface, my mom used to say. Also don’t thin your epoxy with DNA.
How can the pinlines smear if they are done in epoxy resin?..oooh, you did them in paint? Did you thin the paint with any thing like Acrylic floor wax stuff? Acrylic floor stuff & Epoxy or Resin doesn’t mix so well on a glasses surface. it’s best left to foam spraying, it usually leaves fisheyes on sanded coat… Best to do the pins in Epoxy resin, they won’t smear.
If you do them in paint, just cut the paint with a little water.
You could sand it off, but theres no telling what you might do this time. Keep it clean, keep it simple…no touch, no additives, no cleaners.
I think it was a contamination issue too and the part about smearing the paint all over the board may have done it. So you seal your pinlines with what?
Someone also recomended for glossing I use a faster hardener. And yes I did see the pukas forming right away. I think it had to be the acrylic paint because the gloss got all wierd over the pinline.
Resinhead’s advice is first-rate, and foolproof. I find it very hard not to get my grubby paws on the board after sanding the hotcoat, because I do all of my artwork on top of the sanded hotcoat…
My best gloss coats have been over just epoxy, and over unsealed, acrylic thinned only with water (like resinhead said), and I think I’m going back to it. Instead of DNA (denatured alcohol) wipedown, I would wash the board with Dawn dishwashing detergent or a mild car wash detergent, both have worked well. The Dawn and the carwash stuff won’t take the paint off if your last spray coat of paint was semi-wet to wet, and it flowed together well, making a hard shell. If you just dust the coats on, the Dawn will take the paint off, much to my dismay.
You found out the hard way that DNA screws up acrylic, so did I. I sealed acrylic paint with Krylon Crystal Clear and with Aervoe clear acrylic on several boards because I wanted to use the DNA without taking off the paint, but I have had mixed results including 2 disasters like yours; thank goodness I had the squeegee ready to save me some sanding…
To tell you the truth, to keep from having to deal with acrylic/epoxy issues, I am really thinking of using these paints:
I’ve done a couple of UV poly glosscoats over rough sanded epoxy. I thinned it out a bit and used some extra surfacing agent per Kokua’s recommendations. I then run it through a filter cone to get any chunks out. He doesn’t typically use UV gloss resin but I find that once it sits long enough to flatten out a little, the quick cure that UV resin provides prevents other problems like sheeting, runs and bugs.
Don’t use DNA next time, just sand it, dust it off, wipe it with a paper towel. Don’t touch it with you oily grimey hands, use paper towels to touch. You probably had body lotion on you hands, then you started to get all lovey and feel up the surfboard. Less contamination the better…nothing better than a properly sanded surface. A sanded surface is a clean surface, my mom used to say. Also don’t thin your epoxy with DNA.
Above is exactly right. Also double the Additive F, use a new brush, warm the resin slightly, and make sure the air isn’t moving in the shop.
My guess as to what happend to the gloss coat was due to the tape… tiny amounts rub off onto the board and it repells the resin.
Once a board is lammed I never again touch it with my bare hands… gloved hands only. After I grind/sand down the lap line, I use a new, clean paintbrush to brush off the dust, then use compressed air (for computers, sewing machines, typewriters…) to blow off anything that remains. Then I use the same brush (blown clean) to hotcoat. I’ll do the same thing after I sand the hotcoat.
Thank you Swaylocks - I was pulling my hair out trying to figure out why my fill/gloss coats were so puka’d. Fixing a board for a friend that did a costa concordia, routed out the bad stuff, fill w/ mb&RR epoxy, then glass - so far so good, then the hot/filler coat results are in the pic on the right…ARRRRRRRG…yeah I used DNA to wipe down the board (duh). So resanded (man I luv 2 sand), quick wipe, no DNA. Also added more additive F than previously. First try was about 4-5 very small drops of additive F per 30 cc mixed resin small batch. Second try used about 10 drops. Left pic is the results - mo’ betta!
