What is this?

No idea what this is or what I did to induce this. Can anyone tell me what happened so I don’t repeat this error?

 

It wasn’t there before I started the polishing process. I started with 400 grit and moved through 600/1000/1500/2000. I have used the compound yet for the finishing touch and want to know what this is before I do. 

 

Initially I thought it might be “burn” but I kept the board very wet - hosing off after finishing a section etc… and it never felt warm to the touch so I don’t know how it could be this. 

 

Should I just polish and see if it goes away?

Before and after pics. And I didn’t burn through the color as I never hit weave of any kind  

thanks



Why does the color look so different in the close up?

Polyester resin, opaque pigment, polyester gloss on top?

 

Maybe you cooked the polishing compound?  Did you try scraping it off with you fingernail?

Or bad gloss resin and you forced the compound into the resin?  Try carefully touching up a post with acetone?

Why does the color look so different in the close up?

Polyester resin, opaque pigment, polyester gloss on top?

 

Maybe you cooked the polishing compound?  Did you try scraping it off with you fingernail?

Or bad gloss resin and you forced the compound into the resin?  Try carefully touching up a spot with acetone?

 

ps nice looking board and pristine workshop!

Must be the lighting why it looks so different. 

 

Epoxy for all coats and yes to opaque coloring. 

 

I haven’t used the compound yet. Just sanding. 

 

doesn’t come off with fingernail. 

 

Thanks!!

 

I might just try polishing and see what happens

Sorry I can not help you with this problem, but to avoid polishing problems in general, I wetsand my epoxy hotcoats just once rather course with 150-300 just to get it flat and then I apply a 2k PU varnish on top. The PU varnish protects the epoxy from UV rays, gets very hard and most importantly, it shines without any further polishing. Application is done with soft paintbrush followed by a foam brush (you need to work very fast!) to remove any bubbles or sprayed. Better results than ever achieved with polishing and much faster.

Epoxy resin just does not take to the Polyester polishing regime.  Going to 2000 and rubbing compound is over kill.  And you may not have seen it when you did it; but you sanded your filler coat(no such thing as Gloss Epoxy) off of those areas. Personally, I think that is bound to happen when you go thru that many grits.  It’s called over sanding.

But just for mechanics;  After your lamination how many coats of Epoxy?  Did you do a filler coat, sand and then a finish coat.  I am assuming that is what you did?  If so;  What was your sanding process on the filler coat?  What grits?   If you take a little Styrene or Xylene on a clean cotton rag and wipe those areas with the rag on the tips of your fingers;  Does the discolored area change back to the color it should be?  Even briefly?  When the board is wet it is often hard to notice these kinds of things.  I noticed you said you wet the board after sanding each area.  You should be sanding with water on the board at all times or at least frequently spritzing the board with water.  Yes the water helps with overheating, but it primarily reduces friction.  The only reason you would go thru that many grits and compound is because you are leaving swirls, scratches and sanding marks after each grit.  Otherwise if you could W&D at 400 and left no scratches or swirls, you could go straight to #2 Polish and be done.