Just finished glassing and hotcoating my third board and after sanding both sides yesterday, I discovered a stack of pinholes in the hotcoats. I did a search on here and found numerous potential reasons why they happen, but after going back over my process, can’t nail the reason to any one thing. I followed the advice about using gloss resin applied firmly with a squeege pressing down into the affected areas, and after resanding, seem to have fixed the problem on the bottom, however the deck is still yet to be done. My problem here is trapped resin dust in the tiny holes. I’ve hit it with the air hose at 100psi and have managed to dislodge alot of it, but a hell of a lot still remain, and it will NOT budge. I thought wiping down with acetone might help but I think it made the problem worse. The back half of the board is solid black pigment, and the front half is deep blood red transparent tint… so both dark colours which show up these stubborn trapped dust specks. The black will be a wet rub finish, but I want to polish the red, so I’m hesitant to re gloss the deck as these dust filled pinholes will most definitely show up. Please can somebody throw me a lifeline on this one.
I started using a bit more resin in the lam and haven’t had a pinhole issue since. Also my experience that the dust will disapear once wet out with next hot/gloss coat. good luck.
I had a similar problem with pitholes in my glosscoat last week. There are a number of possible reasons as to why this happened and they are all dealing with contamination. A dirty mixing bucket, a dirty hotcoat brush, too much catalyst (causes the resin to shrink around micro dust particles??), a bad batch of surfacing agent. After I laid my hotcoat down and walked away I immediately began to see separation around the dustspecks. In order to get rid of this mess I simply sanded, sanded and sanded some more until I had an even surface to apply a second glosscoat. Another possible source for the problem is pollen?? We had a very late start to our summer here and there is still pollen in the air.
For my next glosscoat I changed most of the variables so I am not sure of the original source of the problem. I had a new mixing bucket, new brush, new surfacing agent and then strained my glossresin as I normally do. I cleaned the bottom with clean paper towell and acetone. I ran a piece of masking tape along the board to make sure all of the micro specks were gone. I also reduced the amount of catalyst by a few cc’s. This one turned out fine.
Assuming this is PU.
IMO it is probable that the lam was thin and your sanding or filler coat reacted and would not fill in.
As I read it you used glossing resin did you “thin it”? To “suck up” and got by on the bottom.
When I mess up, I go to the “sauce”.
No, not alcohol!
Styrene monomer, I use just use catilized UV lam resin w/ surfacing agent and use the styrene to thin out to suit.
dob and poke that’ll suck up.
Follow safety instructions nasty shit…
The problem is that you have failed to mention whether you are using PU or Epoxy. Differant problems associated with each and differant remedies.
Sorry McDing
I’m using Polyester, not epoxy. The pinholes are in the hotcoat, not the Gloss coat. Since the initial post/question, I used some gloss resin applied a thin coat with a squeegee, forcing the resin into the tiny holes, then did a gloss coat as normal. The following day I sanded with 320 and only found one or two still remaining, so problem solved for this one at least… however, I would still like to know the possible cause or reasons why this happened in the first place.
We used to all it “pin air”. When you glass the board you need to make sure the foam and glass are saturated. When you squeegee the extra resin off don’t make it to dry. If is see pin air in the lam I will mix a batch of resin thinned out with styrene and squeegee it in real good. Then hotcoat as normal.
So in the end the problem is usually in the lamination.