French polish vs. nitrocellulose on vintage Martins

My really old (i.e. late teens/early 20's) vintage Martins have, I think, what is called a French polish finish that looks different from the shiny finish that my 40's Martin has (actually my pre-32 2M has this shiny finish too). I suspect that this latter finish is nitrocellulose. Does anyone have information on these two types of finishes and when they were used (i.e. when French polish was discontinued and nitro-cellulose started)? Are these indeed different finishes or does something else cause the difference in appearance. TIA, g2

From what I've seen, I think Martin switched from different types of shellac-based French polish to sprayed nitro finishes some time in the latter part of the 1920's (about 1926 or 27, I guess, around the same time they started using the newer type tuners instead of the "grooved barrel" Grover?) Martin also seemed to have experimented a bit with the new finish during the late 20's and 30's. A lot of the early 1930's ukes have a typical thick and glossy finish, for instance.

[...latter part of the 1920's (about 1926 or 27, I guess, around the same time they started using the newer type tuners instead of the "grooved barrel" Grover?) ... [/QUOTE]
Thanks for the finish information. Just FYI, from what I've seen, Martin used wooden tuners on 0 and 1 models until 26-27 but they were discontinued on 2,3 and 5 models in ~1922. g2

Martin started using nitro on the lower models, without celluloid binding, in the later 1920s. By the early 1930s, everything was sprayed. French Polish is a technique of applying finishes, typically shellac, not a finish itself.

As far as the tuners go, I understand that during the war years, Martin switched back to wood ones.

Thanks Howard, you're right about wooden tuners during WWII. cheers, g

There were intermediate steps; they didn't go directly from French polishing on shellac to nitro. The first change was to brushed on shellac sanded and leveled, then to a modified shellac that was a "spirit varnish". Many of these transition year finishes were what we'd now call satin. The years 1926 (kind of early) or '27 are about right for the change to nitro. I'll have to ask Richard Johnston, but I have a feeling that nobody knows quite when the switch happened, and I wouldn't be surprised to find an overlap period of several months or more from one finish to another. I seriously doubt that there is an absolute day and serial number where they went from one finish to another; that's just not how it works in production shops.

Thanks for the info everybody!
Rick, your info certainly explains the difference in finishes in the pre-nitro years.
btw, in my mother tongue the word for French polishing is "politoeren". No French involved. (our fries aren't French either - they're just "frieten")

One more silly question, perhaps; does anybody have any explanation for the little sanding scratches that always remain quite visible around the bridge area in the pre-nitro ukes? They seem to become nearly invisible in later ukes. Why is that? Did they polish the bodies a first time before adding the bridge? Odd...

Hi Rick, thanks for the great info. I didn't know that French Polish was a technique either. No idea about the sanding scratches WB, you might want to make a separate post on this or post it on the Martin Guitar forum, to get a better response. peace out, g2

Rick Turner said:

There were intermediate steps; they didn't go directly from French polishing on shellac to nitro. The first change was to brushed on shellac sanded and leveled, then to a modified shellac that was a "spirit varnish". Many of these transition year finishes were what we'd now call satin. The years 1926 (kind of early) or '27 are about right for the change to nitro. I'll have to ask Richard Johnston, but I have a feeling that nobody knows quite when the switch happened, and I wouldn't be surprised to find an overlap period of several months or more from one finish to another. I seriously doubt that there is an absolute day and serial number where they went from one finish to another; that's just not how it works in production shops.

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This is what my research indicates, too. Nobody can pinpoint a specific date for the switch (no serial numbers on ukes at that point in time) and the switch wasn't made all at once either. As I said above, I've read that the lower models were the first ones Martin experimented with nitro on; they evidently were uncertain of the effects nitro would have on the celluloid bindings. Years later, we see that nitro yellows such that the white bindings appear yellow, whereas on the shellac-finished ukuleles, the bindings remain much whiter. Just to clarify, they are not the bindings that yellow...it's the finish. I've read that by some unspecified date in the early 1930s, Martin was using nitro exclusively.

Rick has posted extensively in the Luthier's Lounge about finishes. Nitro has a shelf life and on the ukuleles made in the 1930s, that life is coming to an end. When it's new, nitro is a much glossier finish than shellac, an appearance we've come to expect of a "new" instrument. But shellac has held up much better. Unfortunately, therefore, I believe it inevitable that many of these early nitro-finished ukuleles will need some attention right about now. Not to speak for him, but Rick has advised that FP over the nitro will at least preserve what is there and it is reversible should you want to donate an instrument to a museum someday.

Fred, I have a nitro-finished, ca. 1930 3M with those tiny scratches all around the bridge. I suspect that the bridge was attached before the instrument was buffed and they didn't get in close enough around the bridge to polish up the fine scratches caused by final sanding of the finish. This is just my speculation, however.

Just to emphasize...

French polish is a technique, not a substance. The finish is either pure shellac or shellac with additives like walnut oil, gum sandarac, or a relatively new one, Acryloid or Paraloid B-72, and when putting in the additives, the shellac becomes essentially what's called "spirit varnish". Very thin spirit varnish can be French polished on.

Then there are oil varnishes...and that's a whole other thing, and they have no shellac in them at all; they are a combination of soluble resins and drying oils. The traditional thinning medium is turpentine from pine trees. Some "oil" finishes...like Waterlox tung oil...are actually "long oil varnishes". "Long" because they have a high percentage of a drying oil (tung, walnut, linseed, "spike"...which is lavender...etc.). "Short oil varnishes" have more resins and less oil. The definitions are constantly shifting... Oil varnishes are commonly used on violin family instruments and for bright work on yachts..."spar varnish"...and in that case may have UV light inhibitors.

And yes, shellac is a wonderful finish for preserving other finishes like nitro lacquer. It's compatible with everything and yet is unique in being able to be dissolved with alcohol which will not harm lacquer or (in small doses) oil varnishes.

This whole subject of finishes goes on and on and on. I've had to learn too much about it all...

hmgberg said:

Martin started using nitro on the lower models, without celluloid binding, in the later 1920s. By the early 1930s, everything was sprayed. French Polish is a technique of applying finishes, typically shellac, not a finish itself.

As far as the tuners go, I understand that during the war years, Martin switched back to wood ones.

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French Polish is an application technique, dammit!

American Polish is a spit shine. If you get somebody who is French to do the spitting for you, that's okay too, perhaps even better.

Bonnes Frites!

hmgberg said:

French Polish is an application technique, dammit!

Bonnes Frites!

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I realise that, darnit! It's just me English no very good...

Merci a lot for all the info, boys.

Winin' Boy said:

I realise that, darnit! It's just me English no very good...

Merci a lot for all the info, boys.

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Better than my French, for sure.

Thanks for the music! Here's some wonderful playing on a magnificent ukulele, for those of you who don't know Winin' Boy (you should):

http://www.youtube.com/watch?v=xmpCqMb3XKc&feature=plcp