How I varnish a cello (part one)

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Beginning the cello finishing process.

Preparation for varnishing

Once I am sure that all the construction, carving, assembling and scraping is done, I go over the entire instrument looking for “bumps”; tiny discontinuities that will definitely catch the eye after varnishing, but are difficult to see in the white. (Violin-family instruments in the unvarnished state are referred to as being “in the white”, as the color of the wood is very light cream colored, as a rule.)

I use low-angle, relatively dim light to make shadows, hoping that even tiny irregularities in the wood will make enough shadow that I can detect them and gently remove them with a very sharp scraper. In may case, my wife has a better eye for these sort of flaws, so I enlist her help, to find ones that I miss (and invariably, she does). Once the edges, corners and all other surfaces are as close to perfect as I can get them, I brush a weak water-based stain all over it…well…actually, coffee, as strong as I can make it, but it makes only a small change in the color of the wood. the spruce becomes a very light tan, after two coats have been applied and allowed to dry. Between coats, as the water swells the grain of the wood, I sand all over, very lightly, to remover little splinters and rough spots that the water raised up.  I happen to like the spruce grain slightly raised, so I am not trying to remove the “corduroy” effect. I just want it to be smooth to the touch, in spite of the ripples.

Seal coat(s)

I have been using rosin for a sealer…the last cello, I used rosin mixed with turpentine, which worked nicely, but took a few days to dry. This time I am running out of time, and do not have a few days…so I mixed the rosin with alcohol, and a tiny bit of yellow dye. I sealed the whole instrument except the handle area of the neck, using the rosin, allowed it to dry, and put on a coat of spirit varnish to complete the seal. The next step will be a color coat that I hope will define what the cello will look like. If that succeeds, then the remaining coats will be pretty much clear spirit varnish.

So here is what the cello looks like with just the seal coats, as described:

Cello front with one coat of varnish.
Here is the front, with the one coat of varnish over the rosin sealer.
One-piece cello back with one coat of varnish
And the one-piece back, with the grain beginning to show. Varnish does wonders, doesn’t it?
Front quarter view of cello with one coat of varnish
Here’s a front-quarter view with one coat of varnish over the rosin sealer.
Back quarter view of cello with one-piece back, and one coat of varnish.
Back quarter view, same light.
Showing the flame of a one-piece cello back, with one coat of varnish.
Showing the flame of that one-piece back.
Neck joint of cello with one coat of varnish.
Interestingly, the sides were actually cut from the same billet as the back, but that portion evidently had a good deal less flame. The neck is a different billet entirely. Nice flame, there.
Cello scroll with one coat of varnish.
And there’s the scroll. Funny, from this angle, I am seeing things I want to correct. It may be too late. I will have a close look at it tomorrow evening, and make a decision.

Anyway– there you have it. The varnishing process is begun. I use spirit varnish which dries very rapidly, so I may be able to make pretty rapid progress. I hope so– the show is in less than two weeks. 🙁

And after varnishing: final assembly and set-up!


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Oil Varnish Glazing Procedure

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Glaze Procedure for Oil Varnish, Using Artist’s Oil Colors

Procedure for shading or antiquing oil-finish violins:

Water-based Stain procedure

1.      Using a clean brush, and very strong coffee or tea (with instant, you can make it as strong as you want), stain the instrument a nice tan color all over, including the “handle” area of the neck. This will probably take more than one application, but let it dry completely before repeating.

2.      The application of the (water/coffee) stain raises the grain as well, so, between applications of coffee, let the instrument dry completely, then lightly sand it with VERY fine micromesh, to get rid of any major irregularities but NOT diminish the texture (provided you like texture– I do; if you want less texture, sand more.). Sand the handle area mirror smooth between applications of stain. Warning: if you are using coffee or tea, absolutely do NOT use steel wool for smoothing. Iron reacts with the tannins in the wood and especially the tea and turns jet black…so if  tiny fragments of steel end up snagged in the fibers of the wood, they will leave black stains that will not come out. Some of us learn the hard way…

Seal the wood

3.      Once it is ALL the color of tan you want, and ALL the texture you want, and ALL dry, seal the instrument, using a mixture of oil varnish, yellow oil-soluble dye, and turpentine to thin the mix. (How much yellow? Depends on what you want to accomplish…I would say keep it very light.) The oil varnish is usually fairly thin to start with, so you won’t need a great deal of turpentine. It may take more than one coat to seal it–if so, make sure the WHOLE body gets the same number of coats, to avoid creating heavy areas. Allow the instrument to dry completely. I only apply this to the body and the scroll– not the handle portion of the neck. Incidentally, you want to seal the surface, not soak it all the way through. Go easy with this stuff. It is a good idea to sand (lightly, using 400-600 grit) before moving on, and wipe it down with a turpentine-dampened rag. This removes any unwanted particles, and leaves the surface clean and ready to coat again.

Color application

4.      Using Brown Madder Alizarin (Windsor-Newton) oil paint (get artist’s grade, not student grade; the artist’s grade has more pigment), thinned with a little oil varnish and a tiny amount of linseed oil in a small jar, get a mix that is soupy, but not water-thin. (You need the linseed oil to keep it from drying too rapidly) Incidentally, if you want a redder-brown, add a little Purple Madder Alizarin—it only takes a little.

5.      Apply the mixture using a fairly stiff brush, over the entire instrument except the neck (handle area). You might try just one area at a time, until you see what it will do. Get the color into every little crevice. Set the brush aside, and rub across the grain with your fingers. You want the mixture to be starting to set up a little, just as you get the glaze to the color you want. Remember that you will probably be applying two or more coats of glaze, so feel free to rub most of the coat off that you just applied. Rub harder in areas you want lighter, simulating wear. The reason you rub cross-grain is to encourage pigment to hang up in the deeper reeds, and stay there. I use the heel of my hand to get the look I want.

As the mixture begins to set up, you will feel it stiffening– at that point, you can rapidly pat it with your fingers, over and over, leaving hundreds of fingerprints, but removing all streaks. The “fingerprints” all blend together, making perfectly smooth color transitions, and if there are areas that are too dark, you can rub them a little (cross-grain) with a rag. At this point the dark reeds should be pretty visible, and the light areas are the only thing you are blending colors on.

6.      Once you have the whole instrument the color you want (but lighter than final planned color), and no bad spots, let it dry until it is hard to the touch. You can use your fingernail or the tip of a knife to carefully remove or press flat any “zits” that are sticking up.

Varnish between color coats

7.      Give it another coat of the yellow varnish, still pretty thin. When it is COMPLETELY dry, go over it with fine micromesh, to get any little “zits”, hairs, etc. off. Be careful not to rub through into the color coat.

8.      Subsequent glaze coats as needed. (The thinner the glaze coats, the more transparent the final effect—plan on several very thin coats, instead of fewer heavier coats.) Don’t go too far with this–you don’t want to obscure the wood. Check for any areas needing touch-up. Let it dry completely.

9.      Another coat of yellow varnish, or brown, if you want it darker. Allow it to dry, and lightly sand it, with extremely fine micromesh .

Final varnish procedure

10.  A last coat or two (or more, if you wish) of varnish, and final rubdown.

Neck Stain

11.  After the varnish is completely dry I used to use the neck stain from International Luthier’s Supply, in Tulsa (no longer available, as that company no longer exists). Six to eight coats, rubbed in vigorously, with a 4/0 steel wool rubdown between coats, seemed to work pretty well. Don’t apply this stuff before you are finished varnishing—the varnish doesn’t like it at all. (There are other ways to stain necks–take your pick…. Wish I knew what had been in the stuff I got from ILS, but they are gone for good. Too bad.)

12.  Note: I originally used tung-oil varnish for this process, but the process does not require the use of tung-oil varnish—any oil varnish would work; tung-oil varnish dries very rapidly, and just makes the process a lot easier to complete.

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