Melt scratches off your guitar?

StewMac visited Mamie Minch and Chloe Swantner at Brooklyn Lutherie. Mamie shared this great tip for making scratches disappear, while renowned guitar photographer John Peden shot closeup photos.

Behlen Lacquer Retarder

Guitar Repair Vise

Behlen Nitrocellulose Stringed Instrument Lacquer

ColorTone Touch-up Marker

ColorTone Aerosol Finishing Kit

ColorTone Shellac

[fdort]

Thanks for the lesson Mamie! I'm 50 years-old...you are only the 2nd Mamie I've ever heard of. There was a sweet old lady that lived across from us by that name...I miss her.
This tip will help me restore more than my hubby's guitar...thanks!

[Spritsailor]

Mamie, you can make those other tiny micro scratches disappear, and also make your repair look smoother, by rubbing it briskly with a rough paper bag. The heat produced liquifies a thin layer of molecules on the surface and will make it smoother and have less of a cracked appearance. I even did this on a bass neck last week that had a bunch of scratches from a cymbal. You just need to pause once in a while to check your work to make sure you're not overdoing it. Try it sometime! A paper bag is about 5000 grit and free!

[nick]

What a beautiful presentation technique you have - in this world about 'this is all about me ' what's ups' - now what was I talking about?!' you gently stay on track and are really involved - made me want to scuff my old guitar to try this though !!! Ha - thanks from the UK - more please!

[michaeld.mcclish]

Thanks for this tip! I expanded on it. My friend had an old Stella classical that had baaaad water damage on the bottom side of the guitar body, you know, crackled, some of the original finished had popped off. Well, I got the same retarder, taped the bottom corner off, and cut a piece of t-shirt to go over the damaged area, which was around the curve. I slowly dropped laquer thinner onto the cloth, which spread the liquid onto the damaged finish. I used a syringe to drop it onto the cloth, keeping it wet, but not dripping. By checking on it and keeping it wet, the original finish "melted' back onto the guitar. Since I kept the cloth very wet, not much of the finish came off onto the cloth. The damaged area started at strap button, around the bottom, past the inward curve, about 1/4 of the body side. I then let it dry overnight, and started some light sanding. Only a few sections had lost the finish completely and I tried to stain to match, sort of. Then, I finished it off with newer semigloss Varathane clear, and buffed. I'm not a pro, but the repair was pretty darn good. By using the laquer retarder I was able to melt the old waterdamaged finish back onto the guitar, restain a few bad patches, then refinish the whole section. Thanks for this tip, it spurred me onto a successful experiment!

[Eliot-toob]

Mamie mentions that the retarder is n-butyl (aka PGBE), while the can in the video looks like Campbells Care Lacquer Retarder C1611 (PGME). PGBE and PGME are both propylene glycol ethers, so it makes sense they can both act as decent lacquer retarders - but they're not the same. Additionally, the Campbells is 99.5% PGME whereas most n-butyl formulas have several additional solvents with different evaporation rates, such as Mohawk No-Blush Retarder for instance. Also tried to find the Safety Data Sheet for StewMac Retarder to understand it's formula - nothing yet. Which of these works best for your application? The point is you will get the best possible results when understanding more about what's being bought and then always testing wherever possible.

[jeffdevries]

Great method! Thank you for sharing! Mamie, I really like how you find the path of least resistance to get great results.

[thegee-tahguy]

Put a flat heavy iron (no heat) over it before it fully dries to flatten down any high spots. Better results are often achieved.

[bassmentality]

Big Thank You! I really have been helped with the restoration I have done and doing by StewMac. I love the kit and these idea videos are master classes without a doubt. Just wish I didn't have to pay almost 30% import duty for purchases into Europe/Spain!

[s_SoNick]

Mamie Minch and Dan Erlewine are two of my favorite people on Youtube, and I love that this channel shows their videos!

[Hannah-fhsm]

Good activity for those OCD guitarists who can’t tolerate scratches. Dings won’t disappear, but the lacquer retarderdant (LR) helps dissolve the original coat into itself and at least coats the ding. Fingernail and/or wider dings are pretty hard to push out. Appears that the only way you can fill these is by using CA glue with different viscosities, scraping with a masked razor blade, fine grit sand paper, and skillful refinishing. All that work isn’t worth doing on such small dings. But the psychological benefits of “fixing something” with LR is fun...

[raleighburns]

tons of "will it work on this kinda scratch ... " questions. Nitro is part science, part art, and a little VooDoo magic. You gotta try it. At the end of the day you're simply liquifying solid finish and redistributing it. You're changing the geometry of the existing materials. It's going to make what's there flatten out and lay flat and adhere. If the scratch went through to the wood... no it's not going to be invisible. If you're not left with enough material to reflatten and buff to the same sheen it's not going to work as well.... if you simply have a scratch which has moved nitro around.. yes it will work.

[coryballiet]

Nice trick! Finish touch up is something I always struggled with when I worked as a luthier.

[baalzephon]

Who doesn't love a good Nitro huff from time to time? These "fixes" show up like a lightning storm under a black light;) Good job, Mamie.

[mrfester]

This woman knows the science of this stuff and how things work and the reasons why things are as they are and I would trust her with my stuff in a heart beat. I would bet good money that she cares about her work, that she's interested in it and that she enjoys it as well. I knew all that after the first minute or so of this video. That's what told me that she's very good at what she does.
I really got into hearing her explanation for why the scratch took on that color and why she approached the restoration like she did. It made me think of Bluebirds and the refraction of light! Bluebird feathers in certain situations actually appear brown! Anyway... Knowing the "why" helped her, I'm sure, in determining the correct way to make the repair.
I also get the feeling that her biggest concern is doing things right so if by some chance she ran into something that she got stumped on she'd have no problem asking someone who did. None of this false bravado nonsense that ends in messing up your instrument.
I would trust that she can solve problems she's never seen before because she knows how things work. Many people who work with their hands are technicians. They know what to do in a specific set of circumstances but are stumped when they see something unusual or out of the ordinary.
She's got a thumbs up from me.
This lady is no technician. This lady is an artist and I think that's pretty cool!

[frankkolton]

Iva bin dreenking and samelling lacker retarter four years, it hassint efective mee nun.

[Moodo]

What do you mean "don't drink it", what could possibly go wr

[FriendM]

We wanna see you do this process on a Martin spruce top 🤓🥳👍

[spiccolirocks]

I love Mamie Minch! She's awesome, great job as always!

[HeIsGreaterThanUs]

I have a 90 year old Harmony Silvertone or Supertone (not sure) Archtop, and has some pretty bad wear and cracking in the finish in a lot of areas. I like the vintage look and wondered if I could use nitrocellulose lacquer to seal in the wearing that occurred over those 90 years. My main concern being that the cracks need to kinda melt back down and sit flush so when I wet sand it will look good still and not sand through the finish below. Any recommendations for me?

[jonahguitarguy]

I'm thinking spraying the lacquer melt with an air brush might get the scratches to lay down a bit. The brush technique seems to leave a trough.