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Neck dent repair ~ from gouged to glamour   You are logged in as Guest
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estebanana

Posts: 8324
Joined: Oct. 16 2009
 

Neck dent repair ~ from gouged to gl... 

1964 Kohno arrived with a set of pressure dents in the neck that look as though it was pressed hard into sharp table edge. I employed some of my tricks and just like that, they are gone.

Before and after.



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  REPORT THIS POST AS INAPPROPRIATE |  Date May 23 2021 7:34:00
 
estebanana

Posts: 8324
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RE: Neck dent repair ~ from gouged t... (in reply to estebanana

Final result after French polish and color match tinting.





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  REPORT THIS POST AS INAPPROPRIATE |  Date May 23 2021 7:36:12
 
estebanana

Posts: 8324
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RE: Neck dent repair ~ from gouged t... (in reply to estebanana

The tools, plus a soldering iron not pictured.



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  REPORT THIS POST AS INAPPROPRIATE |  Date May 23 2021 7:42:03
 
ernandez R

Posts: 482
Joined: Mar. 25 2019
From: Alaska USA

RE: Neck dent repair ~ from gouged t... (in reply to estebanana

Stephan,

Have you shaped the iron tip in a certain way to make this work?

Do you first remove the finishe around the dent?

I've had really good luck with a small hobby iron, moistening th effected area, two layers of damp paper towel, then working the iron around the effected area. Mostly fixing self inflicted damage pre finish.

HR

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doesn't have to be fast,
should have some meat on the bones,
can be raw or well done,
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  REPORT THIS POST AS INAPPROPRIATE |  Date May 23 2021 14:12:06
 
estebanana

Posts: 8324
Joined: Oct. 16 2009
 

RE: Neck dent repair ~ from gouged t... (in reply to ernandez R

Yes, I use a low wattage soldering iron and heated and pounded the tip into a flatted egg shape. I don’t remove any finish before, I try to keep as much original finish as possible. These gouges were quite deep, in the monkey bite zone. I was surprised that it turned out this good without having to completely strip the neck take more wood out of the neck. It was an arty skill job, not a brute force sand it out job. It was finessed and I think it turned out well.

The pumice was just used at the end as a grain filler in the raw wood spots.

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  REPORT THIS POST AS INAPPROPRIATE |  Date May 23 2021 17:07:33
 
JasonM

Posts: 1682
Joined: Dec. 8 2005
From: Baltimore

RE: Neck dent repair ~ from gouged t... (in reply to estebanana

Amazing!

The guitar that I made has a dents just this on the neck from resting it on a block on the workbench. A lot less severe than this but I can still feel it. Been meaning to try and fix it one of these days. But I was thinking I’d have to sand it out. I’m really surprised the soldering iron was able to pull those deep gouges out!
  REPORT THIS POST AS INAPPROPRIATE |  Date May 24 2021 18:37:59
 
estebanana

Posts: 8324
Joined: Oct. 16 2009
 

RE: Neck dent repair ~ from gouged t... (in reply to JasonM

quote:

ys. But I was thinking I’d have to sand it out. I’m really surprised the soldering iron was able to pull those deep gouges out!


Not all the dent came out with steam heat, but it lifted enough material up so a minimum of original finish was removed in a process of feathering out the discoloration and roughness. After the steam, there was really judicious sanding with a light flat foam block with 180 and then 230 sand paper. Then I used alcohol to raise all the exposed grain, then sanded that very gingerly with some well worn 230.

After this first treatment I alternated between a very light cut wash of shellac put on with a folded piece of cloth to ay down a slick of shellac. When you do this with sanding between shellac coats you cannot use oil. Oil will change the color of the wood under the shellac and change the way the sanding works to fair out the surface.

The Sky Blue Assilex abrasive is the secret weapon. I researched and found this stuff in 2008 through the auto body industry. Its made by the same parent company, Kovax, that makes Buflex, but it has a different function.

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  REPORT THIS POST AS INAPPROPRIATE |  Date May 25 2021 1:17:49
 
estebanana

Posts: 8324
Joined: Oct. 16 2009
 

RE: Neck dent repair ~ from gouged t... (in reply to estebanana

This stuff-

It's designed to track over dips and hollows on the surface you are trying to fair out, sand paper does the same thing, but this one is engineered to do it better and to level without leaving scratches. I think the micromesh from 3M is similar, but this one works better in my opinion.

You wash a slick of thin cut shellac over the feathered out finish after you get the dents at surface level. Then the shellac stiffens the raised grain and holds it so you can take another pass with the Sky Blue which cuts it down without scratching. This step is important because holding the raised grain without it smushing over makes the leveling of the surface go faster and be more true. The cutting power is equivalent to 600 sand paper, but its not a macerating action, it's a micro scraping action.

Once you get the work to this stage you can examine it and do a spot or two of pore filling with pumice to level up any low areas that resemble raw open grain. Then cut the pore filling down with the sky blue. When all the raw wood is sealed and the surface is very close to being faired out flat, you can begin a regular French polish with clear shellac. Then wipe the oil off and pass again with the Assilex. Repeat until you have the surface you want, then pad on a little touch up color, follow up with clear if you like.

I use the Stew Mac tinting colors that come in bottles which are about 20 bucks each, but they last for several years. Amber is the most useful color. Put a half drop on a plate and thin it with copious amounts of alcohol, then charge your pad with shellac and pick up a bit of color. Practice swipe it on on something with some scrap wood with a clear shellac body up already on it.

It sounds like a lot of steps, but it flows together. You have to pause and put the work away while shellac dries, but on a hot day that's about 15 minutes. I think the best way is to not try to do it all in one day however, because shellac shrinks back as it loses solvent, it can take a day or two to totally off gas. So I might get this started by steaming out a dent then some sanding or what ever it takes and get the work to the stage where the first layers of shellac with no oil are going on, then leave the piece over night or a for a few days. When you come back to it the shellac is reasonably 'cured'. It's important because sometimes working over tender, fresh dried shellac can be frustratingly counter productive. Avoid that. You just have to get a feeling for the materials as you work.

Good luck anyone who tries it. I'll be happy to coach you if you get stuck. I hope this info helps any of you seriously trying to learn finish repair.

One other thing, this works best over an existing shellac finish, or otherwise on any finish that accepts a shellac over polishing. Mileage varies on non shellac finishes so keep that in mind and do tests on the shellac compatibility of your existing finish. This method also works very well with varnish finishes.







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  REPORT THIS POST AS INAPPROPRIATE |  Date May 25 2021 1:19:07
 
rombsix

Posts: 7571
Joined: Jan. 11 2006
From: Beirut, Lebanon

RE: Neck dent repair ~ from gouged t... (in reply to estebanana

quote:

in the monkey bite zone




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  REPORT THIS POST AS INAPPROPRIATE |  Date May 25 2021 5:43:48
 
JasonM

Posts: 1682
Joined: Dec. 8 2005
From: Baltimore

RE: Neck dent repair ~ from gouged t... (in reply to estebanana

quote:

This stuff-

It's designed to track over dips and hollows on the surface you are trying to fair out


I remember you mentioning this. Cheaper than micro mesh, right? I wonder how hard it would be to find in the states. Micro mesh is so pricey.

After fairing out when it’s time to shellac, you are starting at the dent to deposit shellac in the deepest part of the trough, let it dry, then keep doing that until you build some thickness, level some, then slowly expand the area out to the edges, kind of like a fiberglass repair job?
  REPORT THIS POST AS INAPPROPRIATE |  Date May 25 2021 16:13:19
 
estebanana

Posts: 8324
Joined: Oct. 16 2009
 

RE: Neck dent repair ~ from gouged t... (in reply to estebanana

It's cheaper in Japan, I get 50 sheets for 50 dollars .

https://www.amazon.com/Super-Assilex-Flexible-Sanding-Sheets/dp/B001TQRUFW?th=1

you might shop around. Used to get it at an auto body supply store

I'm more of less wiping shellac evenly over the whole area, then maybe a few swipes across the areas that I lifted out. You just have to play with it job by job, each condition is different.

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  REPORT THIS POST AS INAPPROPRIATE |  Date May 26 2021 0:48:31
 
JasonM

Posts: 1682
Joined: Dec. 8 2005
From: Baltimore

RE: Neck dent repair ~ from gouged t... (in reply to estebanana

quote:

you might shop around. Used to get it at an auto body supply store


Cool thanks. I think there’s a place in my area I’ll have to look for some.
  REPORT THIS POST AS INAPPROPRIATE |  Date May 26 2021 19:21:06
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