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I am planning on doing a copy of this Gibson L-4 and I can't figure out how to get this color burst. I like to french polish my guitars but I can only seem to find tutorials using cans. also how would i go about getting this great red wine color? any advice would be greatly appreciated.

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That looks very patchy, Patch. I don't know if I would call that a burst as such. It looks more like some of the 19th century trade Violins where the varnish starts becoming very dark. You can't see any grain in the dark areas.
It would be easier with Oil varnish because you could use the glaze method and Oil paints. Spirit is up a few levels of difficulty.
The Violin makers would tend to put on the colour so it ended up dark all over, then sand/solvent remove so that the dark areas remained. With French Polishing you could try getting an even light colour (the lightest colour on that Guitar) and slowly building up for the darker areas. It won't be quick.
There are many tints that you can employ. Seal the wood with clear coats first though. Darker 'Garnet' and Ruby type Shellacs. Modern Aniline spirit soluble tints and/or some of the natural wood dyes such as Alkanet, Brazilwood, logwood. The really dark areas appear opaque, so it will require a very dark tint: maybe a touch of Black added. Shellac.net have a variety of Shellacs including a Black type. I haven't used that so I've no idea if it's appropriate. I might try adding a bit of LampBlack as an experiment. It might work, it could fail completely. This kind of thing requires a lot of experimenting (and money, I'm afraid) on similar scrap wood. If you can get some colour on the wood first (through UV tanning) it will make the task a little easier.

I had a Gibson "O" - the one with the curlicue and cutaway, that had a deteriorated finish. When I stripped off the crusty top coat and repolished with some truoil I wound up with a similar blood clot finish.
You might try applying black dye stain , sanding most of it back off then restaining with red dye stain, then french polishing over it.

Typical teens Gibson mandolin color. I have done quite a few using Trans-Tint red with a dab of TT medium brown added. Depending on the look you want, you might first dye the instrument amber, then apply the red. Use Alcohol or water as the dye base, and try on a bunch of scrap before the instrument. Spruce tops will naturally turn splotchy with application. Do not apply a wash coat of anything as it will muddy the final look.
Here is a back I did quite similar to what you are looking for but maybe a bit darker...



You can do more of a burst too or "cherry" it up with the amber underneath...



You must spray a coat or two of shellac over the dye before french polishing.

I'm no expert, but that looks more like the color was rubbed directly into the wood, not sprayed.

If you are doing an actual French Polish and not brushing shellac on and sanding it then it appears to be fairly straight forward to me.

I have restored a few furniture pieces by French Polishing so I know a bit about it. I would suggest using a Garnet Flake and building up the overall finish to get the color depth. To apply the burst I would use the same Garnet but would use more mineral oil as you work the shading in so you get a smooth blend. Also make sure you go out from the edge the same distance on each coat starting out at the first inch or so from the edge, the next coat would go out 2 inches and so on. Repeat until you get a deep burgundy blend.

After I got the color and blend as I wanted I would switch to Blond Flake to get the desired gloss and finish you want. The blond will protect the blended areas from light scratches going through the color. You can also use pumice if you need to flatten the surface out with out going through the Garnet layers.

I use the method of applying French Polish with a mouse (also called a rubber or tampon) by loading the wad up with shellac and applying mineral oil on the rubber. I also apply straight mineral oil on the wood prior to using shellac which will make the garnet go on smoothly and not become blotchy. When I did the blend I would dab mineral oil on the rubber more frequently which will let you smooth the blend out much easier.

I was taught French Polishing many years ago by a woman that had done it most of her life. She showed me a few different techniques but I found that the method above works best for me. I know some people use more shellac and much less mineral oil which requires less coats but it is also much less forgiving. And some people apply shellac as the first coat and the use pumice to fill the grain.

That is how I would do it but then there are many different ways to achieve the results you desire.

Cheers,
Bob

thank you all. lots of great methods and ideas to digest and experiment with.

michael.n. i'll have to try oil varnish, it's something i don't have any experience with.

haans, great looking mandos!

rusrob, thanks this makes lots of sense to me. probably what i'll experiment with first since i kind of understand french polish finishing more than others. mouse same as muneca?

thanks again!

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I'd say the wood was stained. It wasn't unusual at the time to use tinted glaze coats on top of a stained base color, but I couldn't tell you for sure in this case from just a picture. If I had to guess, I'd say stain only.

AFAIK Gibson originally used oil varnish, and then switched to NC lacquer. Did they ever use FP other than as a glaze top coat?

As far as I know Gibson never used French Polishing. I answered Patch in the framework he asked the question. He said he was familiar with French polishing and since I have done it and know a bit about it I answered him in those terms.

@Patch,


Yes, I have always referred to it as a mouse or pad.

You may have to end up dying the wood first or try tinting your shellac to get that deep burgundy (I think you can tint shellac with clothes dye). I am not an expert on the topic of French Polishing so maybe some one here would know more about it than I do. I have done it enough to feel comfortable with my own abilities so take my advice for what it is worth (free...)

Cheers,
Bob

Haans,
that mandolin looks great - love the finish, however you did it.