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Scratch removal

Postby BJG145 » Thu Jul 11, 2013 11:00 am

I'm wondering about trying a potion to lessen some fine (and not-so-fine) scratches on the surface of a black acoustic. Do they work? I asked about products like T-Cut and Eternashine at the local guitar shop but they just looked blank and said there was nothing you could do about it.

http://www.guitarscratchremover.com/
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Re: Scratch removal

Postby zenguitar » Thu Jul 11, 2013 2:35 pm

The best way to deal with scratches is to stop worrying about them. Treat them as well earned battle scars and forget it.

Sure, you can polish out scratches. But within a few days or weeks you'll get new ones, and you'll want to polish those out too. And all that time looking closely at the finish while you polish means that you start noticing fine scratches that you previously wouldn't have spotted. Before long you start giving it a regular treatment all over to keep it nice and shiny. And after a while you get patches where you have completely worn through the gloss coat and are trying to get a shine on the colour coat.

All of these scratch removers are a very fine abrasive in a liquid/paste carrier. They work by removing material. Polishing out a scratch can be done in two stages. When you cut into a finished surface (which is what a scratch is) the edge of the scratch is a sharp edge which catches the light and draws the eye. So light polishing will round that sharp edge so it does not reflect so obviously; the scratch is still in the surface but it becomes less noticeable. The next stage is to remove more material around the area of the scratch to completely remove it. This leaves a slight dip in the surface which will remain visible as a flaw in the reflection on a gloss finish, like a distortion in the surface of a mirror.

T-Cut will work, but I wouldn't recommend it. It is designed for Car paints which are very hard (the paint on a car has to withstand the abrasion of fine dust in the air at speeds in excess of 100MPH) so it is a very aggressive cut.

Brasso and Silvo are a similar grade of grit as T-Cut and produce a similar finish. Both are less aggressive than T-Cut. Silver is a harder metal then Brass so Silvo has a more aggressive cut than Brasso. Both are useful in the workshop but Brasso is a far better option to use on finishes. You can get a very good gloss finish on an instrument with Brasso and a lot of elbow grease.

Autosol is a much finer abrasive in a paste used for polishing metal, so it is a little more aggressive than ideal for guitar finishes. However, used with care it is OK because it is such a fine grit.

I don't know the product you linked to, and their FAQ's don't actually tell you anything about the grit of the abrasive or the composition of the carrier cream. But I would expect it to be the same grade of grit as Autosol but less aggressive.

If I were to reduce/remove a scratch I would just use Brasso, and maybe a final buffing with Autosol. Alternatively, I would consider using the same sort of polishing compounds used for guitar finishing like these Colour Tone polishing compounds from StewMac.

But I generally wouldn't bother on my own guitars, and would advise against. It just isn't worth it.

Andy :beamup:
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Re: Scratch removal

Postby Hugh Robjohns » Thu Jul 11, 2013 2:47 pm

Just a thought, since you mention car paint polishers... what about using one of those colour-matched scratch fillers intended for cars? They can be pretty effective on car bodywork adn work by concealing the scratch rather than removing it.

I've never tried it and have no idea if it would work on guitar paint, but raise it purely as a possibility?

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Re: Scratch removal

Postby BJG145 » Thu Jul 11, 2013 5:28 pm

zenguitar wrote:Treat them as well earned battle scars

I would if I could...but they were more likely caused by some other twit who couldn't play not taking care of their instrument. I don't generally care if things are a bit scruffy, but I'd like to give this a bit of a "reboot". I was wary of falling victim to snake-oil purveyors, but the brasso plan sounds interesting...
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Re: Scratch removal

Postby zenguitar » Fri Jul 12, 2013 12:39 am

Hugh, I've also looked at those scratch fillers for cars and wondered. But I just don't know enough to know whether or not they would be any good on guitars or other paint/lacquered finishes. My gut instinct is that they are coloured waxes that load the scratch when they are applied. They hide the sharp edge reflections that draw the eye, and the body colour is close enough to be better than a scratch. But that is just my best guess.

BJG... You could do a lot worse than Brasso. I apply it with something like kitchen roll, work in large areas rather than just attacking the scratches, and then when it dries I buff it off with a soft cloth (yellow dusters are my favourite). It usually takes two or three applications to get a good shine, buffing it with a clean cloth after every application, and I do like to clean the guitar with White Spirits before I start and after each application. That is usually more than enough to remove all the fine scratches, greatly reduce the big ones, and get a good shine. But if you need a higher shine an application of a tiny amount of the Autosol with the same process will do the job nicely. But please resist the temptation to achieve perfection, all that does is remove way too much of the original finish.

Andy :beamup:
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Re: Scratch removal

Postby Kwackman » Fri Jul 12, 2013 9:08 am

If the guitar is worth it, maybe look for a local french polisher-if that skill still exists?
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Re: Scratch removal

Postby Martin Walker » Fri Jul 12, 2013 10:29 am

zenguitar wrote:Brasso and Silvo are a similar grade of grit as T-Cut and produce a similar finish. Both are less aggressive than T-Cut. Silver is a harder metal then Brass so Silvo has a more aggressive cut than Brasso. Both are useful in the workshop but Brasso is a far better option to use on finishes.


Now there's something else I didn't know - I always assumed (wrongly it seems) that Silvo was more gentle than Brasso because it was being used on more expensive metalware :headbang:

Thanks Andy!


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Re: Scratch removal

Postby zenguitar » Fri Jul 12, 2013 1:04 pm

Kwackman wrote:If the guitar is worth it, maybe look for a local french polisher-if that skill still exists?

Traditional French Polishers are very rare now and those you can find are very expensive. I know a local guy who is a very good finisher with paint and shellac, but he doesn't do traditional French Polishing like the old guys who used to visit bank branches in the 80's to maintain those lovely old counters.

However, shellac is a very good finish for touching up repairs because it adheres to any other finish and is generally very benevolent. But I wouldn't bother with it for scratches for a couple of reasons. The first is that it takes a lot of time and experience to match the colours, a guitar will have a colour coat (black in this case) and a clear top coat which is polished to a gloss finish. You can't get perfectly clear shellac so there will always be a faint colour difference in the filled scratch. The second reason is that you have to do a lot more polishing to get the shellac flush with the existing surface so it is a lot more work than just polishing the scratches out.

A good rule of thumb is that most chips and scratches can be reasonably disguised but it is very rare to be able to make them totally invisible. And in some cases filled chips and scratches can appear invisible in normal light but suddenly become very obvious under bright stage lights.

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Re: Scratch removal

Postby Gary_W » Fri Jul 12, 2013 2:42 pm

Obviously Andy knows more about such things than I'm ever likely to - so all I'm telling you here is what I did and what the results were :)

I bought a 2nd hand G&L Asat Special (tribute series) from eBay. Price was right. Played well once I'd set it up but the seller's description of 'mint condition' fell below my expectations - it was scuffed and scratched. It's a standard finish, nothing vintage and fancy.

I used http://www.meguiars.co.uk/product/198/ScratchX-20/

It's a lot milder than T-Cut..... And it improved things a great deal. It won't get anything major out but the minor scuffs and polish marks (where some divot has cleaned it with a cloth that has grit on it :roll:) improved a great deal.

I then finished it with their deep crystal polish. Looked great and both products were considerably cheaper than stuff supposedly made for guitar.

No issues were caused doing this. I started gingerly on the back but soon discovered that the scratch x did nowt visible to the guitar except for improve it.

The usual YMMV bottom-covering statement is now applied - it worked for me :D
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