In my on-going quest to learn all the ways epoxy and fiberglass can be challenging, I noticed small, pinhead white dots while sanding my fill coat. I think this means I’m just touching the glass but I don’t know if it means I need to go a bit farther with sanding or if I already went a bit to far.
From this blog post (discovered elsewhere in the forum) https://www.bob-easton.com/blog/2010/1394/ the author’s first picture looks similar to what I’m seeing. However I’m worried about sanding through the glass so I don’t want to do anymore until I get confirmation that I still have room to sand.
After wetting the spots with alcohol they are still visible but not the end of the world. I’m also not sure if they will look different under another coat of epoxy vs the alcohol. I could definitely live with them but if this is common and there is an easy fix (like sand more), I’m all ears.
experts may have another (better!) suggestion, but here’s mine:
the white material is the very fine epoxy sanding dust nestled into low spots in the fiberglass cloth. I had that in a few places. I assumed that to get rid of the white spots I would have to sand almost all the way through the ‘glass which I didn’t want to do. so I used a stiff toothbrush soaked in denatured alcohol and was able to dislodge almost all the sanding dust from the pits.