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Removing scratches

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Removing scratches

Postby Karl Ruffing » Tue Mar 25, 2014 1:19 am

I'm new here so my question may seem very elementary to most of you, but what is the quickest (and safest?) method for removing scratches in a finish? They are on a side of an archtop guitar and it is natural maple. I don't believe that the scratches are into the wood, just the lacquer.
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Re: Removing scratches

Postby David King » Tue Mar 25, 2014 3:00 am

Karl,
The first thing to determine might be where the scratches are coming from. Make sure that there isn't a metal rivet or nail protruding from the lining. You would hate to put a lot of effort into fixing it just to have it happen again. If you can post a photo I'm sure that would help us recommend an appropriate approach.
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Re: Removing scratches

Postby Clay Schaeffer » Tue Mar 25, 2014 7:27 pm

If the scratches are too deep to buff out, you may want to drop fill the scratches with finish, re level , then sand and buff. Do you know what type of finish it is?
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Re: Removing scratches

Postby Karl Ruffing » Tue Mar 25, 2014 8:25 pm

It is nitrocellulose lacquer over natural maple. And the scratches were caused accidentally by me. I am not a guitar builder or even a person with woodworking skills. The guitar is new and I just want to remove a few small surface scratches the quickest and safest way possible. I would appreciate any suggestions. I'm thinking they could simply be buffed out.
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Re: Removing scratches

Postby Barry Daniels » Wed Mar 26, 2014 8:57 am

Buffing cannot remove deep scratches. Typically these need to be wet sanded, then polished, then buffed. Doing this risks buffing through the finish into the wood, creating a much worse problem. Lacking experience, I do not recommend you attempt this repair. Take it to a professional luthier, or learn to live with it. Sorry I could not be more helpful.
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Re: Removing scratches

Postby Clay Schaeffer » Wed Mar 26, 2014 9:08 am

If the scratches are not too deep then hand buffing with an automotive polishing compound may remove them. Generally speaking, the more expensive the instrument, the thinner the finish (although it may not look that way) so if it is a nice instrument you should take it to someone who can inspect it and give you good advice. Without seeing the instrument it is hard to say what is the best way to go.
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Re: Removing scratches

Postby Karl Ruffing » Wed Mar 26, 2014 11:56 am

Well, thanks for the advice. You have convinced me not to attempt to do this myself. I am located in a very small town of 4,000, so I will try to find a luthier in Calgary, which is a one-and-a-half hour drive away. If I am unable to find someone who can do this, then I'll just leave it be as it is not really that big a deal and hard to spot.
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Re: Removing scratches

Postby Michael Lewis » Thu Mar 27, 2014 3:11 am

The first scratch is always the biggest, no matter how small it really is. Part of the human condition is to make the grand canyon out of a small issue at first. It may be an easy fix or it may require a more involved approach, but we can't tell without seeint the problem.

It is very easy to make a small issue into a bigger one by trying to "fix" it. Recently a customer called me to ask how to buff off a dull area on his guitar. His problem was that he had already rubbed off the finish, and that was the dull area, which was getting bigger the more he rubbed on it.

It helps to have a practiced eye to inspect the problem, to see if the wood is dented or not, to see if the finish is fractured or just scratched, is wood exposed, and to see how deep is it. Typical finish on an archtop is about .005" or just over .1mm.
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Re: Removing scratches

Postby Karl Ruffing » Fri Mar 28, 2014 2:11 am

I see your point, Michael. It is really a small scratch. I was lowering my metronome and accidentally brushed it against the side of the guitar and it left a scratch, about 1/2 an inch in length, but it is unsightly, even if it is somewhat difficult to see. However, I know it is there, and it bothers me tremendously. So it is onward to Calgary.
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Re: Removing scratches

Postby Bob Gramann » Fri Mar 28, 2014 9:42 am

If you plan to use the guitar, you will eventually put more blemishes in the finish. Along the lines of "You can't have your cake and..." why not accept the mark as a sign of a loved guitar? There will be more.
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Re: Removing scratches

Postby Karl Ruffing » Fri Mar 28, 2014 12:29 pm

Well, as I have said, this is a small town of 4,000 and there really are no venues for performance and I don't know anyone with whom I might jam, so I guess I'll just be playing for my own amusement. It is kind of like a person with a new car, isn't it? The first scratch or ding is heart-breaking, but then it is just a means of transportation. And you are correct; there will be more. This I'm sure of from past experience.
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Re: Removing scratches

Postby Michael Lewis » Sat Mar 29, 2014 3:17 am

Karl, if the finish is not separated/open/cracked/etc. it will be safe to leave it until sometime in the future when it can be better inspected and advised. If the finish IS interrupted so moisture and dirt can get to the wood then maybe something should be done sooner than later.
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Re: Removing scratches

Postby Karl Ruffing » Sat Mar 29, 2014 12:22 pm

It is OK. There is no exposed wood and I will leave it alone for now as I attempt to locate a luthier in Calgary. Thanks for all your advice.
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Re: Removing scratches

Postby Tom Sommerville » Mon May 12, 2014 2:02 pm

A question to all:
Suppose Karl picked up a pint of lacquer thinner, or acetone, carefully masked the area 3mm or so on either side of the scratch, and using a fine sable or similarly soft brush, lightly flowed or puddled the solvent into the crack, allowed it to flash off, and then repeat? A few repetitions should amalgamate the sides of the scratch. After a few days, the immediate area could be lightly leveled with 800 and higher, and then buffed.

I don't work with Nitro very often, but I seem to recall getting a decent mend this way on a repair.

I also recall using denatured alcohol on a pad to blend, or "pull" some brushed lacquer once, and it worked satisfactorily.

It's been years, but has anybody done anything like this ?
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Re: Removing scratches

Postby Michael Lewis » Tue May 13, 2014 1:40 am

IF it is only a scratch then a bit of thinner would help heal the 'open' surfaces of the finish, however, if it is a dent the new lacquer could level toe surface but would not change the underlying reflectance of the wood, and the dent would still be visible.

Regarding masking and lacquer, you only mask where you want a crisp break between two areas. In the case of a spot repair no masking, use a brush to 'drop fill' the missing finish, level and buff after it has dried thoroughly for a couple weeks.
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Re: Removing scratches

Postby Jim Hobson » Sat Mar 09, 2019 9:33 am

Dan Erlewine, of StewMac fame, is generous with serving up his decades of acquired knowledge on such things. He created a video on how to repair scratches in a guitar There is no fast, easy way to repair damage to fine finishes. This video gives clear instruction and details on how to do it, but it takes a little bit of time. I think you will find your answer here.
The real secret to a happy life is making good decisions.
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Re: Removing scratches

Postby Clay Schaeffer » Sat Mar 09, 2019 12:05 pm

There is a lot of good information on line these days (and also a lot of bad) but one thing it doesn't give you is experience. Finish repair is an area where looks are everything and it is also very easy to make things look worse rather than better.
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