Bubbles in epoxy lam

General Discussion
1

I'm building a board with my brother, and we did the bottom lamination yesterday evening.  We're using 4oz cloth with epoxy with a yellow pigment over a polyurethane blank.

Everything looked fine when we finished the lam, but a few small bubbles came up subsequently.  They're not "foaming"-type micro-bubbles, but more like small ridges where the the glass has just lifted slightly from the foam.  I'm not even sure that there's air in them - they may be filled with resin.

Also, and I'm not sure if the problem is related, there is also a very small bubble running along the stringer (there is definitely air in this one).  I have read about stringer out-gassing in the archives, but we glassed in the early evening with falling temperatures; and also I've previously done a board with the same type blank and had no problem with out-gassing on the stringer.

So, 2 questions:

1. How do I make sure that we avoid the problem when we do the deck?; and

2. How do we deal with the bubbles that are there now?

Regarding the second question - the bubbles are small enough that if the board was for me, I'd just carry on and do the fill coat.  However, the board is for my brother, and he has really high expectations on how this is all going to turn out :-)  (As it is, this board is way better than the previous board I did, at the same stage.) 

Any assistance will be appreciated.

Tim

2

Sounds like dry cloth. Maybe, because epoxy takes longer to “kick” the resin drained into the blank, leaving the cloth dry. If the cloth has lifted away from the foam, and it’s not filled with reain, you need to cut it out and patch it. You need a good, tight lamination everywhere. If it’s filled with resin (you can tell by pushing on it with your finger), there’s nothing you can do, really. Just pull more excess out next time.

The bubbles along the stringer - I’d just poke a few tiny holes into them, and they’ll fill with the hotcoat.

What blank/resin/hardener did you use?

3

I'm not at home now, and my inspection this morning before work was fairly brief - so I'll have to check later whether there's air in the bubbles.

I used a Surfblanks SA blank, and Gurit Ampreg 21 resin/hardener system.  The Ampreg 21 system is not a clear, but sort of tea coloured.  I previously used clear Gurit SP 115, but the supplier didn't have any in stock.  Seeing as we were going to use a pigment anyway, we went with the Ampreg 21.  According to the spec sheet, it's meant to be significantly stronger and have better wetting properties than the clear resin.