MB100,

This is a tough one as Poly builds in layers and does not melt into the layers below like lacquer.

Sand the area with fine grit paper, 400-600 grit. Put a few coats of poly on that spot sanding between. Lightly sand entire surface with an 500 or 1000 Abralon foam backed disk on ROS to blend. Then a final coat over the whole surface??

Do this with the test piece.

The alternative is painful.

Good luck

 

It takes time and patience. I've used this method to repair nicks in car finishes. If there is any loose material in the chip outs, remove those with light scraping and brushing. Then use a very small pointy something like a pin or tooth pick and put a small drop of poly in each chip out. Let it dry. Then do the same again and again until the dried poly has built up slightly higher than the surrounding area. Then, using finer and finer grit wet/dry sand paper on very small sanding blocks or sticks, sand it smooth and level with the surrounding area. Work through 6000 grit to give it a good polish.

 

Several ways to repair it. If you want quick and cheap. Use a magic marker of a close color on the spots and rub the spot over with your finger to help blend in. Then apply a wipe on finish over whole top. You might be surprised with the results. I've been able to hide marks this way with different restoration projects. Depending on where the spot repair is, you might not even need to apply a wipe on finish.

 

Hmm, one sweating beer glass can hide those marks?

It takes time and patience. I ve used this method to repair nicks in car finishes. If there is any loose material in the chip outs, remove those with light scraping and brushing. Then use a very small pointy something like a pin or tooth pick and put a small drop of poly in each chip out. Let it dry. Then do the same again and again until the dried poly has built up slightly higher than the surrounding area. Then, using finer and finer grit wet/dry sand paper on very small sanding blocks or sticks, sand it smooth and level with the surrounding area. Work through 6000 grit to give it a good polish.

- bilyo

+1
Gloss finishes are easy to repair using automotive methods.

Use some mineral spirits in divots to clean out dust and see if wood stain needs repair. Damaged wood color makes repair more difficult.

Another trick with top coat repair is to use plastic scraper (old credit card), when your drops of finish are higher then surface. Will level the spot, but tends leave a halo or tracks adjacent to damage. Finish will shrink as solvent evaporates, so it requires a couple of fill steps. Still scraper saves on sanding. Level with 1000-1500grit, and go straight to buffing step with a foam pad and automotive polishing compound. Meguiar's PlastX, or Micro polish and small foam pad works on fully cured poly (give single part finish 3-4 weeks, 2K can be polished in 48hrs). Once repair is done, a coat of hard furniture wax will even out any sheen differences.

Best Luck.

 

Shellac burn in stiks, requires practice. Most of the time I just rub some dye or stain to match ( go slightly dark vs light, hard to get exact match). After a year you wont notice, and no one else will notice until you point it out. Poly is about impossible to get a perfect repair.

 

A lot of repair luthiers use CA/Glueboost for fixing poly guitar finishes. Plenty of info and videos on line.