Polyurethane Scratch / Dent Repair with Fingernail Polish

nprenger

Junior Member
Joined
Dec 27, 2013
Messages
23
Reaction score
23
I haven’t posted very often, but I’ve learned a lot from you guys. I tried something that worked really well, so I figured I would give something back by sharing it with you and permanently document my method in the process.
This repair was done on an SG, but it just as easily could have been done on an Epiphone Les Paul because the finishes are the same material. Don't worry - I share your enthusiasm for Epi Lesters.
I bought a used Epiphone G-400 as a project guitar on eBay a few weeks ago. It was listed as ‘mint’. It wasn’t, but it was close. Absolutely gorgeous guitar – 1961-style with the smaller pickguard, rootbeer quilted maple top – and to top it off, it played really well right off the UPS truck. Shortly after I got it, the polyurethane finish started to flake slightly where the finish ends at the fretboard. I tried to even it out by scratching at it with my fingernail, and before I knew it, a 1/8” x ¾” chunk of poly was completely gone. Bare rosewood. This would not do.
Here’s what I did to restore it to a smooth, mirror-like finish.
Step 1: Use a sharp X-Acto knife to carefully remove any loose polyurethane finish at the edge so the new edge will be firmly adhered to the wood. This step ensures that you won’t have any bubbles when you’re finished.
Step 2: Apply a thin coat of clear fingernail polish to the area of bare wood. Don’t try to brush it out. This stuff dries quickly, so the more you mess with it, the more brush marks you will have. Blow on it to help it dry so it doesn’t run. Put the guitar down and let it sit overnight. Repeat this process until the fingernail polish is slightly thicker than the factory poly finish. It might take 5-6 coats.
Step 3: Apply a few more coats by the same process concentrating on the interface between the fingernail polish and the poly. The purpose of this step is to ensure that there will not be any voids between the two finish materials.
Step 4: Let the fingernail polish cure for 5 days. I’m not sure if it’s absolutely necessary to wait this long since it dries so quickly, but I wanted to make sure it was good and hard so it would polish to a glossy shine.
Step 5: Use 800-grit sandpaper (I bought 3M brand from the local Home Depot) to sand the fingernail polish flush with the poly. Don’t take away any more material than necessary to get it smooth and uniform. You’ll have to be careful not to sand through the finish. This is where the extra coats of fingernail polish pay off. Wipe the area clean with a damp cloth.
Step 6: Soak 2000-grit sandpaper (also 3M from Home Depot) in water for a few hours. Use it to wet sand the area to remove the larger scratches the 800-grit left behind. Rinse the sandpaper after about every 5 seconds of sanding to remove the residue from the paper so it won’t cake and cause more scratches. It shouldn’t take much sanding to get a nice, uniform haze free of the larger scratches. Wipe the area clean with a damp cloth after every 30 seconds or so of sanding to inspect it so you’ll know when you can stop. You can expect a really fuzzy haze after this step, so don’t make the mistake of trying to polish it out with the sandpaper.
Step 7: Use automotive polishing compound (I used Turtle Wax brand – available at any well-stocked auto parts store) to remove the haze and bring back the shine. Don’t confuse polishing compound with rubbing compound. Rubbing compound is more abrasive and may reintroduce deeper scratches. Rub the polishing compound in for about a minute for a smaller area and use a damp cloth to wipe the area clean. Look for scratches. Repeat until no scratches remain. It might take 5-6 total minutes of polishing to get everything looking good. You should now have your glossy finish back, and it should be blended well with the factory poly finish.
Step 8 (optional): Use automotive cleaner wax (I used a can of Mother’s that I had lying around) to lightly buff the area. Buff clean with a dry cloth. You could also use your favorite guitar cleaner for this step.
Step 9 (also optional): Use automotive finish wax (I used a can of Meguiars yellow paste wax) to really bring out the shine. You could also use your favorite guitar polish for this step.
Here’s the proof. Photo of the guitar:
IMG_2573%202.jpg

Here’s a close-up of the restored area. The area with the fingernail polish on it appears darker because I used a black Sharpie to make the white fret marker roughly circular again. It had become damaged when it was bare wood. Because the rosewood looked lighter without the finish on it, I used the marker on the whole exposed area to darken it. I wish I hadn’t done that. Overall, I would call this mini-project a success, though.
IMG_2576.jpg

Light reflecting off of it to show the single continuous glossy surface:
IMG_2577.jpg

IMG_2574.jpg

 

Tenacious T

Senior Member
Joined
Dec 14, 2007
Messages
3,809
Reaction score
1,973
Well done. Clear nail polish works great on those little touch-up's.
 

Curmudgeon

Senior Member
Joined
Jun 24, 2013
Messages
2,273
Reaction score
2,350
Really nice work! :applause:Gonna use this technique on a headstock blem on my '56GT.
 

nprenger

Junior Member
Joined
Dec 27, 2013
Messages
23
Reaction score
23
Thanks everybody! It turned out better than I expected, and it was easier than I thought it would be too.

Really nice work! :applause:Gonna use this technique on a headstock blem on my '56GT.

Let us know how it turns out. By the way, my plan is to join the P90 club with this guitar, install a Batwing pickguard to cover up the pickup routing, and add a Bigsby just for grins. I'm also going to change the wiring to 50's style and maybe try a few tonal improvements that I haven't already tried on my LP. Oh, and the pointy body is just begging for Keystone-shaped buttons on the Grovers.
 

Teeceman

Senior Member
Joined
Nov 29, 2013
Messages
227
Reaction score
134
Belated HNGD...
I have to agree, that is one beautiful SG.. very nice repair job too :thumb:
 

Fuelish

Senior Member
Joined
Jan 27, 2008
Messages
2,781
Reaction score
1,231
Nice DIY!!!! Nice guitar :cool: Not normally a SG fan, but that is a REALLY nice lookin' one, I could definitely live with that :) ....on second (or perhaps third) thought, it's not that I'm not a fan of SGs, it's just that I cannot afford any more guitars... at the moment. Again, ...nice guitar, great touch-up work :cool:
 

nprenger

Junior Member
Joined
Dec 27, 2013
Messages
23
Reaction score
23
This is slightly off topic, but it turns out that applying steps 5 through 9 above works really well for cleaning up oxidized polycarbonate headlight lenses, too.

The masked headlight has been polished. The opposite has not.

IMG_2582.jpg


Close-up of the unpolished headlight above after polishing:

IMG_2583.jpg
 

smac4th

Senior Member
Joined
Feb 22, 2015
Messages
201
Reaction score
71
This is slightly off topic, but it turns out that applying steps 5 through 9 above works really well for cleaning up oxidized polycarbonate headlight lenses, too.

The masked headlight has been polished. The opposite has not.

IMG_2582.jpg


Close-up of the unpolished headlight above after polishing:

IMG_2583.jpg

The head lights on my 04 passat were real bad. Just wet sanded them and used buffing compound then waxed them to protect them and they look new. Saved myself $400 by restoring them. I actually found the whole process fun.
 

nprenger

Junior Member
Joined
Dec 27, 2013
Messages
23
Reaction score
23
Great! I'm glad it worked well for you. I thought it was kind of fun, too. There isn't a whole lot of risk involved since the lenses have to be thick enough to withstand impacts from small rocks and such. If you leave some scratches, just sand and buff some more! A few bucks and a little bit of your time to improve visibility in the dark is kind of a no-brainer.
 

Latest Threads



Top