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Hi all.

I'm doing a repair on a friend's old beat-up guitar where a hole was patched. I decided to try only using shellac to finish to see how that would work. Once the hole was patched, I sanded down to bare wood on the repair area. The side is made of walnut that has a lot of runouts, actually it's practically endgrain! My problem is that the area I sanded down to bare wood does not seem to seal properly, and the shellac (2 lbs cut, by the way) keeps sinking and sinking into the wood. It seems there is no end to it.

What do you think I should do? Sand back and seal with CA first?

Thanks!

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

It is not common for shellac to sink deeply into the wood even at end grain. No!!!!! do not use CA!!!!!!!!!! it will stain softwoods very badly deep into the cell structure.

a photo will help to see what is going on.

second I am hoping this guitar had shellac finish in the first place or there will be major witness lines between the old finish and the FP'd area.

Thanks for your reply Michael.



Yep, that's the plan! It is already agreed with my friend that there would be witness lines all right. That is no issue. It will actually blend in quite well with the rest of the guitar which seems to be made out of witness lines!

Anyway, here is a picture (the best I could take). You can see two major area:

- a big round area where the shellac shows OK on top of the old finish
- a smaller round area in the middle of the first one where I sanded down to bare wood. That is where the shellac keeps sinking in. (Although I seem to be seeing light at the end of the tunnel, I think...). Since there was no pore filling done on that area, pores are showing big times. But again, that is not the issue.

Thanks again!

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

Alain;
The old finish looks cloudy-unclear!
Your repair area makes the wood look good again !!
Load that area with Shellac and buff with steel wool to match the original !!

Mike

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Mike Collins

agreed on how to make the two areas apear cohabitable, I suspect that the shring bak you are seeing is lack of pore fill

Thanks Mike!

Indeed the old finish is not the best I've seen. Some pale filler was used to pore fill and it pretty much kills sweetness of that walnut.



I didn't think it coulds have that effect. I'll know it for next time.

So you guys think I should just keep on building up with shellac and eventually I'll see something shining?

Thanks!

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

After building it up you could go the pumice pore filling route. Not too hard to do on a small patch like that, as long as you don't mind having one little spot outshine the rest of it all.

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"Preoccupation with an effect gives it power and enhances the error"
from "Your Owner's Manual" by Burt Hotchkiss.

Hi again.

The shellac is still being sucked in by the wood. But I discovered one thing that might be important: my shellac bottle is at least two years old. Could that be the cause of my problems?

Thanks again!

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

Yes old shellac is a problem but this is still not adding up to me. Shellac does not tend to be adsorbed by the wood. It almost Does not penetrate into wood at all even on spruce and cedar tops except when applied to end grain and even then is not absorbed by the fibers very much. It does not penetrate but microscopically. This is strange

Ok, then.

And what is exactly the problem with old shellac? (Just curious...)

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

usally failure to harden properly. ie stays somewhat rubbery

I see.

It doesn't seem to be the case here since the shellac that was applied on top of the old finish (so this one didn't sink in) was hard enough to sand it with 400 grit this morning.

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

Ok, here is some progress (or regression more so... )

Maybe it's my technique that's wrong (after all, it's my first time trying a shellac only finish...), but It's not the wood that isdrinking the shellac away more than it is me who seem to be wiping the shellac off by trying to apply a new coat. I seemed to have something shining this morning and as soon as I applied a new coat, all the shine went away and it was back to the wood fibers again!

Should I apply with a brush instead?

Thanks again!

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

Fists are you just applying shellac to a pad and wiping? If so this is not FP this is padding. Second regardless of FP application or padding the shellac will dull as it gases off.

It is difficult to apply a FP or even a padded application to a small area that in essence is a recessed area of sanded back finish. The shellac will want to go to the outer perimeter because you are going over and over in the same area so it pushes away to the outer edges. This very well might be better done with a brush.

Well in that case, yes I'm padding. I just thaught applying shellac was French Polishing. What is the difference? The use of oil? (Just curious again...)


That seems to be what is going on here. I tried just tapping my pad on the area instead of wiping and it seems to be better. I'll just keep on doing so and if it doesn't work, I'll try a brush.

I'll let you know how it worked out.

Thanks a lot for your help!

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

This came up with me just last night as I was French polishing a myrtle guitar. I started one session with a pad that was much too wet and ended up creating essentially a 3-inch diameter crater in the finish.

Trying to simply add shellac to that area was only slightly successful as it built up on the perimeter as Michael said. Had to sand level and start from a flat surface.

At least it gave me an idea of how thick the finish was...

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Evan McCartney

This is French polishing: http://www.milburnguitars.com/fpbannerframes.html

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Waddy

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Sound Clips of most of my guitars

French polishing is an application method that wicks semi-dried shellac from an inner pad through an outer pad and leaves it on a surface. The combinations of these two pads are called the muneca. Each later session is 100% melted into the previous and is spirited off to remove lube oil and level as you go. This builds a singular amalgamated film not padded on layers. Once the film is built to desired thickness it is then glazed in a similar process except with thinner shellac per muneca load to produce a burnished polish surface. French polishing is vastly different than padding.

Hi Evan,

I'm originally from Potomac, MD. Welcome to OLF (if you're new)...

I've had a little more luck in that situation when I let the spot (and the overwet muneca) dry out a bit, and then go back to start building the inside of the crater up with several bodying-style sessions. The ridging still happens at the edges, but when I got to level sand (after the shellac has hardened enough), I find I'm just sanding off the outside ridge. Usually a little bit of glazing over the spot smooths out any remaining irregularity. Don't know if that makes any sense.

- Flori

That's great to know; thanks very much. I'm sure I'll leave more spots and get some practice at the technique. I probably wasn't patient enough in trying to rehabilitate the spot.

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Evan McCartney

The story of my life...