Hotcoat problem

General Discussion
1

Hello, 

I’m having a problem with a polyester hotcoat, after I made the bottom of the longboard, pinholes started to appear in some areas. After sanding I’ll give a Gloss Coat, my concerne is that the gloss coat doesn’t cover this pinholes, as it happened on the last longboard I did. To solve that, I used some UV resin, but It was painful to cover each one of them (AHAH). So I would like to hear some opinions, to help prevent this, and if Gloss Coat doesn’t cover up, what’s the best choices I have. I found some good information in the archives, maybe it can be related with a lot of variables, like temp, humidity, outside/inside, mixing bucket… but would like to know a “fresh” opinion.

The board I’m working is a 9’4 longboard (6oz bottom and 2x 6oz deck) with a tail patch. Laminated with light grey resin tint.

I Hotcoated the deck first, and no problems with pinholes, just did a mixture of Silmar resin 249BB (1200kg* a bit more than necessary, as I have little experience* + 4% Wax in styrene + 2%Cat) and went OK.

I was proud of the deck hotcoat. After thar I made the bottom with almost the same quantities, just add a bit less Catalyst, because that day was hotter (20ºc in glassing room). So, 1200Kg resin +4%/48g wax in styrene + 1.75%21gr Cat. When I was applying hotcoat, at the beginning I passed the squegee over the board, to resin get inside. When finished, I started to see in some areas of the board pinholes appearing, I’ll attach some photos. I’m worried about that because last longboard I have done had the same problem, and cant find a reason for that.

I was thinking maybe should be the quantities of Catalyst, should put a bit more/less?

Can also be the way I mixed the resin, I had to stear well to mix with wax in styrene. After mixing it seems that the resin was not as translucent as before (I think it’s normal, even if you move slowly it happens);

Environment of the glassing room, I have a fan, but works really slow when hotcoating and its above my head, doesn’t directly interfere with the board;

 

Want to mention that the deck’s hotcoat went well, and it was with almost the same conditions. In deck I had the 2x6oz, at bottom 1x6oz, maybe have some dry areas there.

 

 

All advice is welcome, cheers!

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2

Hello; where do you find that resin in Brazil?

Regarding that; those are not pinholes but debris from the wax and some previous dust on the surface; sometimes, in the used brushes too. When you add silice (aerosil) you can have those too.

That would be not a problem and after the sanding (with a polisher and 60 grit then 100 grit) should gone. If some pinholes remind after that; clean with compressed air and then wipe off with styrene monomere. Then another pass with monomere now would be ready for the pinlines or gloss coat.

3

Sand it until all that stuff is gone and then gloss it…  You have got a decent thickness on the hotcoat, so it should sand out.  Reverb could be right.  Might be undisolved wax or other junk in your hotcoat.  Always make sure your Surface Agent is shook well and dissolved.  If it is prepackaged Sanding Resin, stir it really well, making sure the surface agent is dissolved in the resin.  No chunks or flecs.  You should strain your resin also.  If your resin is older, thin it a bit.  Make it more workable.

4

Hi reverb, 

I’m in Portugal, I think the resin was in good condition and fresh, but never sure about it.

I’ll try to sand it and see what happens, then wipe it well with alcohol or monomer and gloss with a new brush.

@mcding thanks, yes it is a thick hotcoat. Here I made my own sanding resin, mix some wax in styrene, but one day would like to try that prepacked sanding resins.