Leveling a low spot in a French polish finish - created 12-21-2008

Merritt, Lauren - 12/21/2008.17:52:14

I'd appreciate some input from the repair gurus on this one.

This guitar was damaged in shipping last year (some of you may remember the discussion), and I've been slow to complete the repair. Truthfully, it's still painful to think back on the whole experience!

The top was cracked between the bridge and rosette, and one leg of the X brace was cracked. I did the structural repair a few months ago: worked glue into the soundboard crack and cleated it, then glued and reinforced the broken brace with glue-saturated cotton fabric. This all turned out quite well, and the crack is invisible from the outside. I followed the guidance I got here last year, so thanks to all who chimed in.

The remaining problem (and the reason the guitar has been gathering dust since the structural repair) is the finish. My repair left a depression in the area of the crack and I'd like to bring it level. The finish is FP, and I've spent a good deal of time with the muneca trying to build enough to sand it level, but apparently that approach isn't going to pan out until this time next year.

I hesitate to level sand without building the finish first because I'm concerned that I'd have to sand wood and thin the soundboard in one spot. I'm considering using another finishing product like Behlens Rockhard to build this small area so I can level sand and complete the finish repair with FP. Is this a valid approach, and can anyone suggest a different one?

You can see (I hope) the depression in the two photos I'm uploading. A bit hard to catch with the camera, but I think you'll see what I'm talking about.

I plan to keep this guitar as my own, so the only customer to please is myself. Still, it's a matter of pride to get this right and an opportunity boost my repair skills. Thanks!

Use a thicker cut of shellac. Use short sessions. Let it harden well in between.

I see some color change between the two areas. Make sure you are using the same shade of shellac.

I would think that FP is the best choice for repairing this, rather than any other product.

I've experienced a sort of a halo effect when trying to deal with that type of issue. I think was was happening is the muneca was catching the higher edge and taking off more shellac, darkening that edge. I never was able to satisfactory overcome my problem, but upon reflection I've been wondering if I should have been carefully pushing the shellac from the outside of the area toward the center, rather than the usual figure 8 pattern. Any thoughts?

I have experienced the "halo" effect. Most often, I have a area near binding which needs filling. I have to work it more than other areas. The pumice grinds away some of the darker binding material, depositing it around the area I have worked more agressively.

If I am not looking at the guitar in bright lights, I don't notice it until later.