I’m still honing my shaping / glassing / sanding skills and want to know the difference between a burn-through vs kiss the cloth. I know when I’ve sanded way too much and get a true burn through but am I ok when I can see the “+” of the cloth. I’ve got a couple of spots where I can see the cloth but there still seems to be that hotcoat layer. Am I ok in these spots or should I brush on some extra resin on these spots?
If you see the cloth, that means you are sanding it. If you are sanding it you are damaging it, and it gets weaker. And then yes, you need to recoat over the exposed cloth.
And epoxy and resin are different. Because epoxy doesn’t flow as well, I put down a hot and then sand it to where I’m just barely touching the weave. Then I lay down a xylene thinned top coat. Thinned isn’t as strong, but it flows smooth. That last coat should be easy to sand fair, without touching weave at all.
If it was easy, it wouldn’t be a trick. So keep practicing.
Sanded more boards than I care to count.
It happens to the best of us.
Key is a really clean gloss-like Hot Coat.
Sand the hotcoat, not the glass.