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french polish - dark spots under first body session
dan g.

Total Topics: 12
Total Posts: 27
Howdy folks.
So after about three evenings of pumice pore filling, I finally got to the point where I thought I was ready to start padding on the shellac.
I spirited off the entire guitar with straight alcohol to (hopefully) clear all the pumice.
There were a few areas where some darker spots remained, which I took to be places where some shellac had started to build up.
I went ahead and did a first bodying session, and now those dark spots are there under the first layer of shellac.
Has anyone had experience with this?
Will they likely be removed or become less noticeable during subsequent body sessions and leveling?
Or do I need to deal with them somehow... I guess my only option would be to remove the first shellac layers (with alcohol?) and then continue on with the alcohol to scrub away those dark spots?
I realize pictures would be helpful, so I'll try to get some tonight.
Mostly just curious if this has happened to others during french polishing.


Mar 25, 08 | 7:52 am
dan g.

Total Topics: 12
Total Posts: 27
Well, I got to working on the polishing again this evening.
For some reason, the spots didn't stand out as much as they did last night.
I think I've resigned myself to accepting them, and hoping that they blend a bit as the shellac finish builds (unless someone convinces me otherwise).
For what it's worth, here are a couple photos (in which you can't really see the spots very well, but you can sure see the shine the shellac is putting on!)

<img src="" width="500" height="375" alt="guitar back after first shellac session.JPG" />
The spots are mostly sprinkled in on the bass side of the back. They're a bit more prominent than this photo captures, but not too much.

<img src="" width="375" height="500" alt="back after first shellac session 2.JPG" />
Another view, they're even less visible in this one.

<img src="" width="375" height="500" alt="top after one shellac session.JPG" />And a view of the top, just because I'm so happy with how this is turning out so far. Such a transformation to start to see the "finished" look of the guitar!

Mar 25, 08 | 10:27 pm
Bill Cory

Total Topics: 158
Total Posts: 3584
Dan -- I've had that spotting effect in the past, but not with French polish. I theorized that it happened to me because I had in some spots sanded through my sealer coat while leveling the pore filler; in those areas, the wood took on a darker appearance.

As I said, that was my "theory." I don't know it for a fact. It only happened with one guitar, early on.


Mar 26, 08 | 4:57 am

Total Topics: 1
Total Posts: 81
I am going to guess the spotting is a function of the direction of the wood grain. Also, the application of alcohol to "spirit off" before you FP might have enhanced the dark spots where the wood grain becomes "wetted" more in the end grain. Perhaps as the guitar "dries out" the spots will even out some, but since the grain is still varying some, it probably won't even out altogether.

If it is the same as what I am thinking, this spotting is very common in Cherry, for example, and is lessened by sealing the wood before finishing. That way, you get little penetration of the finish into the more exposed parts of the wood grain, and a more even wood color.

Still, yours looks pretty good to me. Good luck and have fun.

Mar 26, 08 | 6:49 am

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