by ddemasie on Mon Dec 14, 2015 12:43 pm
Hmmm...
This is just my opinion and practice:
From your description - I think you are actualy putting too much epoxy on in the first coat. I believe that if you do it right, after applying the first coat of epoxy, the fiberglass cloth should become transparent, but the point of the first coat is not to make it completely smooth to the touch, but just to form a strong bond between wood, cloth and epoxy. My first coat is always thin enough that after curing, I can still feel (and see) the weave of the glass if I rub my hand across it. it ddoes become transparent, ut you can still see that it is cloth. The second and third coat of epoxy 'fill the weave' and provides the additional strength.
I think that youe experience of seeing the weave of the fiberglass cloth is in places where you have put on too much epoxy, and the cloth is 'floating' on top of a layer of epoxy, and no longer making direct contact with the wood.
I do my first 'wetting' in one thin epoxy coat - just enough to adhere the cloth to the wood, then add 2 thicker coats in succession to add the depth and additional strength to the finished product.
I generally try to add the second and third coats within 12-24 hours of the first. Timing here is approximate and sometimes hard to control (since I have a regular job and cannot always approrpiately schedule epoxy coat timings), but the idea is that you want to get the second and third coat on before each previous coat fully cures (definitely within 24 hours) so you get a good chemical epoxy bond between the coats.
I only sanded between coats of epoxy if I had to wait over 24 hours between coats (or sooner during the summer when it is warmer and the epoxy tended to cure very quickly) - and sanded just enough with 80 grit to get a basic 'dulling' of the shiny, slick top layer of the cured epoxy. Doing that helps the new layer bond mechanically to the more fully cured layer of epoxy.
So - no, I did not generally sand my interim epoxy layers down to the uniform dullness needed for painting, though I did try to get most of the 'spikes' from cured epoxy cut down with a small hand held stainless steel blade that I bought from CLC for this exact purpose - look on the CLC website for them - great investment and a necessary tool.
Dennis DeMasie,
Aurora, IL