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Shellac - French Polishing


Doc Eastman
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Has anyone used shellac (resin from India lac bug) dissolved in alcohol to finish violin family instruments? Searched on it and only found 1 reference relating to using it in a ground of madder root extracted with alcohol. Used by Spanish to finish fine classical guitars. Involves sealing with shellac, filling open grained wood (like mahogony)with shellac, oil and pumice (no filling needed for closed grain wood like maple and spruce), then loading up successive layers adding mineral oil (baby oil) in late stages, and then clearing with alcohol rub down after hardening. Similar to finishing with spirit based coatings. CD from Int. Violin shows the pocess. Very labor intensive if applied by pad, but can be loaded with a brush. Very fast drying. Only get 1 pass with a brush, max 2 on a cold day. Harder to work with than oil based varnish. Beautiful glassy finish that is very easy to repair (also easy to ruin by the unschooled). Susceptible to water damage and dissolves with alcohol. Have attached photo of back of my first cello finished in this way. Tone is excellent. Would greatly appreciate thoughts on this aproach.

post-44249-0-54879400-1315575977_thumb.jpg

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French polishing is used by some makers as a final stage of varnishing (just for new instruments). The problem of using French polish for the whole process is that it will be difficult to add the colour to the varnish, I think. Guitars poses little problems in relation to varnish colour.

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French polishing is used by some makers as a final stage of varnishing (just for new instruments). The problem of using French polish for the whole process is that it will be difficult to add the colour to the varnish, I think. Guitars poses little problems in relation to varnish colour.

Thanks for the response.

Adding color too the shellac is easy, because shellac is compatible with spirit varnish. I added some dark brown spirit varnish to the shellac for a couple of coats. It is very difficult (for me) to get an even coat when color is added. Strobel points out in one of his books that this is a problem wih spirit varnish that will "hopefully" average out after many coats.

I was taught to "french polish" oil based varnish as a final step using oil and a sprinkle of pumice, but oil varnish dries too slowly to apply the way shellac is applied by french polishing (successive coatings at one sitting with a pad, for example).

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Shellac, by itself, is not often used. Spirit varnish contains shellac as a major component, and is used by some makers. One problem with it (and spirit varnish) is that it dries too fast. Sometimes certain oils are added to lengthen the drying time a bit, to get a better surface.

That appears to be why mineral oil or baby oil is used later in the process. I have also heard of using pure lavendar oil.

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That appears to be why mineral oil or baby oil is used later in the process. I have also heard of using pure lavendar oil.

I've done some french polishing with straight dissolved shellac in my time on guitars and bows. The baby oil is needed (very little) to keep the "rubber" from sticking decreasing friction on the built up layers. It comes to the top of the successive coats and needs to be spirited off - removed with a light pass with straight alcohol. Another problem besides its durability and incompatibility with water spotting is that it tends to be shippy when thicker-less elastic than oil based varnish.

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My current spirit varnish method - I use it on my hardanger fiddles - involves french polishing. With a lot of practise, it's not too difficult to apply colored varnish evenly. In fact, I find it more difficult to brush spirit varnish evenly! And when brushing, one often get them ridges at the edge of the stroke..

A combination of brushing and french polishing is what works best for me.

But to be easy to french polish, the varnish might have to contain mainly shellac. I used to soften it a lot with mastic, but had to switch to a little castor oil only, when I started to do more french polishing. That produces a rather hard varnish, which is fine (and traditional) for hardanger fiddles.

This one is varnished using this method. (Varnish is thin, still color is strong and quite even!)

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You mention ridges at the edges of brush stroks with shellac. I have something that was brushed with shellac and has those ridges. Is there a way to smooth those out? I don't have any experience doing french polish. Could I just rub over it with an alcohol pad maybe with a few drops of oil on it but no shellac in it? Sort of a shellac eraser ?

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My current spirit varnish method - I use it on my hardanger fiddles) - involves french polishing. With a lot of practise, it's not too difficult to apply colored varnish evenly. In fact, I find it more difficult to brush spirit varnish evenly! And when brushing, one often get them ridges at the edge of the stroke..

A combination of brushing and french polishing is what works best for me.

But to be easy to french polish, the varnish might have to contain mainly shellac. I used to soften it a lot with mastic, but had to switch to a little castor oil only, when I started to do more french polishing. That produces a rather hard varnish, which is fine (and traditional) for hardanger fiddles.

This one is varnished using this method. (Varnish is thin, still color is strong and quite even!)

What a beautiful finish and fine work! You confirm what I have found. I notice that if no ground is used (no UV, stain) to color the light wood that the color is considerably lighter. I have a test piece going where I used Old Wood Golden Ground Solutions A and B, which give a nice brown patina, followed by multiple coats of shellac. I am getting the same coloration as you appear to have in the photo without adding any pigment to the shellac. Note that shellac comes in a range of colors from platinum to orange. Check out www.shellacshack.com. I use their blond dewaxed shellac.

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You mention ridges at the edges of brush stroks with shellac. I have something that was brushed with shellac and has those ridges. Is there a way to smooth those out? I don't have any experience doing french polish. Could I just rub over it with an alcohol pad maybe with a few drops of oil on it but no shellac in it? Sort of a shellac eraser ?

Item DVD 25, International Violin, by Ronald L. Fernandez suggests wrapping fine grit paper (say 400 machine paper) around an oblong eraser, and with baby oil lightly going over the ridges. Note that these coats are quite thin and easy to cut through. Oil is part of the process, so is not a problem. It eventually works its way to the surface and is wiped off during the alcohol process at the end called "Clearing".

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Item DVD 25, International Violin, by Ronald L. Fernandez suggests wrapping fine grit paper (say 400 machine paper) around an oblong eraser, and with baby oil lightly going over the ridges. Note that these coats are quite thin and easy to cut through. Oil is part of the process, so is not a problem. It eventually works its way to the surface and is wiped off during the alcohol process at the end called "Clearing".

I like this idea better than scraping. with scraping I'm afraid I may go too deep all at once. Can you explain 'clearing' ?

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Item DVD 25, International Violin, by Ronald L. Fernandez suggests wrapping fine grit paper (say 400 machine paper) around an oblong eraser, and with baby oil lightly going over the ridges.....

Gosh... Haven't seen, and probably won't see, the CD, but I don't think I'd ever use something as course as 400 grit on varnish... especially instrument varnish. Wouldn't take long to go right through the film. If the ridges were that severe, I'd probably use a very sharp scraper, with little or no turn to the edge, first.

IMHO; Too much manipulation (leveling, etc.) of a varnish coat, combined with French Polish (either in application or to finish off the coating) makes an instrument resemble a bowling ally... or a polyurethane finished plank table.

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I like this idea better than scraping. with scraping I'm afraid I may go too deep all at once. Can you explain 'clearing' ?

I was going to suggest the 400 grit paper and the eraser. That is the way we smoothed lacquer finishes in guitar work. Couple of suggestions: use the kind of paper that is used for automotive finish. Round the edges of the eraser and watch out for the edge of the paper. You can go from the 400 to 600 and then fine steel wool to get out circular scratches. I never used oil, but mineral spirits. Check on a test piece I don't think it will screw up the hardened shellac but I might be wrong. It evaporates quickly and powders up the abraded shellac, wiping of easily, not filling the paper grit and allows you to see how you have lowered the high spots. Easy to go through the uneven finish to the wood though and you have to add more finish between levelings anyway.

Clearing is removing the surface oil with a quick light rub of achohol on the rubber, never stopping the motion so as not to disolve the shellac.

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  • 2 weeks later...

Has anyone used shellac (resin from India lac bug) dissolved in alcohol to finish violin family instruments? Searched on it and only found 1 reference relating to using it in a ground of madder root extracted with alcohol. Used by Spanish to finish fine classical guitars. Involves sealing with shellac, filling open grained wood (like mahogony)with shellac, oil and pumice (no filling needed for closed grain wood like maple and spruce), then loading up successive layers adding mineral oil (baby oil) in late stages, and then clearing with alcohol rub down after hardening. Similar to finishing with spirit based coatings. CD from Int. Violin shows the pocess. Very labor intensive if applied by pad, but can be loaded with a brush. Very fast drying. Only get 1 pass with a brush, max 2 on a cold day. Harder to work with than oil based varnish. Beautiful glassy finish that is very easy to repair (also easy to ruin by the unschooled). Susceptible to water damage and dissolves with alcohol. Have attached photo of back of my first cello finished in this way. Tone is excellent. Would greatly appreciate thoughts on this aproach.

FYI

I am attaching photos of my violin #9 (after the 1694 Strad poster) Finish at this point is:

3% gelatin, 2 coats

Old Wood 1700 Golden grounds solution A. Color developed by exposure to sunlight on the slope of Mt. Shasta T 3500 feet. 2 coats

Old Wood 1700 Golden grounds solution B. 1 coat (stops photoreaction and fixes color and enhances color).

Clear ground spirit varnish (InternationalViolin.com) 3 coats.

Blonde shellac (ShellacShack.com) reconstituted in denatured alcohol 2 pound cut (2 oz flakes per 8 oz alcohol). No color added. Dissolved for 2 days, filtered through a coffee filter.

Shellac loaded with a wide brush in 3 passes to cover a plate, no overlap, no second pass, no sanding between coats. 6 coats applied in one day.

post-44249-0-64473800-1316353807_thumb.jpg

post-44249-0-10770000-1316353863_thumb.jpg

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[MeyerFittings is suggesting auto sandpaper instead of hardware store because the auto stuff is closely graded to eliminate all over-size particles. With the hardware stuff you risk getting a big particle in there and end up scratching the finish instead of smoothing it.]

I don't like high gloss and have rubbed out with a little fine pumice and oil. Any thoughts about this versus micromesh versus the auto stuff (black, silicon carbide "Waterproof Sandpaper" is what I think you are referring to) used wet (oil for shellac) or dry?

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Beautiful work Doc.

Have any of you tried oxalic acid for purifying shellac?

I have been doing in my natural shellac after I de-wax it running through 2 coffee filters....I think I see a difference...

By adding about one-half ounce of oxalic acid to the quart of orange shellac varnish its color is brightened and most of the impurities are removed.

After adding the acid stir it, let it settle over night, then pour off the clear solution, throwing away the dregs.

from:

The expert wood finisher; a complete manual of the art and practice of finishing woods by staining, filling, varnishing, waxing, etc (1912)

Kelly, A. Ashmun (Albanis Ashmun), 1849-1928

http://www.archive.o...oodfinish01kell

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I don't like high gloss and have rubbed out with a little fine pumice and oil. Any thoughts about this versus micromesh versus the auto stuff (black, silicon carbide "Waterproof Sandpaper" is what I think you are referring to) used wet (oil for shellac) or dry?

Doc,

My preference is pumice or rottenstone with oil. I find the cutting very easy to control. More important for me is texture. I find that any material which has a backing...like sandpaper of micromesh...no matter how soft the backing....tends to flatten the surface.

Joe

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Doc,

My preference is pumice or rottenstone with oil. I find the cutting very easy to control. More important for me is texture. I find that any material which has a backing...like sandpaper of micromesh...no matter how soft the backing....tends to flatten the surface.

Joe

When I was recommending the sandpaper I thought that I was referring to a build up or ridge or drop of dried finish that was wanting to be leveled. There is no need for this leveling if all things go well in the application. I never had any luck with scraping dried shellac since it is so brittle and wants to chip. Certainly Jeff is right in the danger of going through the finish to the wood. I used this technique to level screw-ups not as a way of doing french polish. Actually I usually started with 600 grit and just kissed it initially and then added another coat then kissed it again. Wet sanding is a big part of lacquer finishing but thats another animal and not the same thing at all. I need to look at the International video.

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