www.KitGuitarsForum.com

My 1954 00-18 has had a tough life. In college it was a favorite of the "borrow" crowd. In grad school it survived a fire in our building. Finally I have decided to make some repairs and restorative touchups while waiting for some materials for my cocobolo and spruce J45 build to arrive.

Problems:
One side of the rim was apparently repaired before it was purchased from Sam Ash music in Brooklyn around 1958. The repair was done by putting a glue soaked fabric patch over the damage and refinishing the outside of the rim in the area of the patch. While the refinish area is pretty good it is noticeable in strong light. For the moment I want to leave that area as is.
In the heat of the fire a crack developed in the top of the lower bout. I can see the crack on the inside with a mirror but a strong laser flashlight does not show any open space through the crack.

There is a typical pick guard crack. It has been partially repaired in the past by bridging it with a small block of spruce on the underside. The crack extends under the pick guard and that area has not been repaired. Again I can see the crack thought the top with a mirror but no light shines through.

I removed the pick guard. Although I heated it with a heat gun and pried with a spatula the heat did not soften whatever glue was holding the guard and the spruce under it delaminated. There is no hole in the area but there is a paper thin layer of spruce, attached at one edge, separated from the underlying spruce.

There are numerous scratches and dents in the finish, some to bare wood.

There is a shallow crack in the rim at the lower bout, on the side opposite the patched crack. I do not see that this penetrated the mahogany.

Some of these areas I know how to restore. The rubs and pick rash on the spruce top I can repair using permanganate to oxidize the wood to its current amber look followed by touch up with Behlen nitro lacquer.

The rubs on the rim and bottom I can dye match and retouch with the Behlen.

Some of the fixes though I'd like advice on. For the area under the pick guard I am considering re gluing with one of the following: yellow titebond original. Or quick set epoxy. Or All wood epoxy. Or SB112 system. After gluing I was planning to prime the repaired area with SB 112 with fused silica thickener. In one tips video Dan Erlewine uses paint-on cyano to prime and harden under the new pick guard. Opinions on best procedure?

In another tip Dan uses amber medium cyano to repair a long crack and slivers of spruce to fill in where light shows through. Since the crack is tight I am planning to use only the amber cyano. Opinions?

One other. I was thinking of shooting the behlins with an airbrush or a touch up gun. At the Martin factory they use a brush and drop fill thickened lacquer. Opinions on best way?

I'd like to solicit thoughts on these various repairs.

Thanks
Bert

Yes, Dan is Dan Erlewine.

Thanks for the ideas. There is no evidence that any of the bracing has loosened or cracked. The heat damage occurred some time around 1967, and i have played the instrument a lot since then, with no buzzes or other acoustic evidence of brace problems. Also, i have examined the interior carefully with a mirror and strong flashlight many many times in anticipation of the point at which i might feel comfortable doing repairs, and i am certain the bracing is sound. The long crack in the lower bout seems solid, as I mentioned, but no light passes through. I did try the amber cyano repair shown in his tips video, and, yes, it looks like crap. But, it's done, and the crack in the finish i have scraped flat with a razor (rounded off the ends so it doesn't scratch) and sanded with 600. I hope to get to try a lacquer fill with a narrow brush tomorrow. Other places on the top where the finish was breached with small nicks - 1-3 mm in diameter, the amber cyano worked well to fill the depression and add the right tint. I'll scrape and sand those areas, and drop fill them.

The area under the pick-guard I will probably repair with Titebond. I don't really see the advantage of hide glue there, except of course for the long open time so i can cover the glued area with waxed paper, and apply a caul and clamps. And of course, hide glue contracts, which would tend to pull the delaminated parts tighter to the underlying wood. Hmmm - maybe hide glue is the right stuff after all. Blonde shellac will be easy to make up in small quantity from flake, so, i will go ahead and use that to prime and consolidate the fibers where the pick guard goes back. And, the part of the pick-guard contraction crack that is not yet repaired i will repair with a small piece of cross-grain sitka left over from a build-project.

When done, I will add ebony bridge pins (certainly not original looking) with a little flash from a tiny dot of MOP in the head, as well as an ebony end pin.

I was considering polishing the machines, which are the open type, but, my guitar-head son voted to leave the patina. So I will.

My objective is not to refinish, but to restore it to some likeness of a well-used, but old instrument that was better cared for than it actually was.

Thanks again for taking the time to write your reply.

Bert

SB112 is a finishing resin and not a bonding resin. It would be OK to seal the wood with but not as an adhesive.

Yes - thank you. I will probably use the hide glue and shellac primer approach though.

bert

I tried out an artist's airbrush with the un-thinned behlen's out of the can. Almost no overspray, and for the long crack in the lower bout, i think it made a nice layer over the repaired crack. In some areas i had a chance to rub with 600-1000-2000-4000 abralon to see how it would look before compounding and polishing, and I believe I can flatten and rub out the lacquer so that it will be hardly noticeable. In a few other spots i used a tiny artist's brush and drop filled with the same lacquer. A few drops will probably be necessary to build up to the original finish, but i think for the tiny dings that technique will work ok. The area of the pick-guard is presently being clamped after spreading hot hide glue. I feel pretty confident that with the advice above, and some effort, i can conceal some of this guitar's hard-life history. I am also trying to assemble some dyes to color match the mahogany, but getting it exact will be difficult. I can see that it is tinted red-mahogany with a slant towards brown, so that a bit of green dye in red mahogany would be a starting point. I did like a previous suggestion about using a piece of glass as a mixing palette, so that i can see through the color and get a pretty good idea of how it will look on the wood. I have to find a small piece of glass, though - maybe from an old picture frame.

bert