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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:
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!
Thank you for the well written article. I’m debating my next bass guitar build as a hollow body instead of drowning the wood with lacquer and paint and killing the sustainable of the wood I am very serious about using your finishing techniques and what brand of chemicals would you recommend. Both are stringed instruments and hollow body. I’ll be grateful for any advice and views about my little project. Thank you.
Robert, I attempted to reply to your email address. Still waiting for a reply.
Chet where did you get the rosin and what was the ratio of the mix?
Great article. Thanks
Bob
Bob, the rosin was just some broken pieces of violin rosin, crushed and dissolved in turpentine, fairly thin. (no idea of the actual ratio.) I have also used pine resin harvested from trees that had been recently trimmed: every limb-scar had gobs of thickened sap, and I collected a pound or more. I dropped it all into a gallon jar and poured in both turpentine and denatured alcohol, and stirred it a bit over a few days. Then I poured off the solution into smaller jar as I had need for it. the bits of bark, dirt, etc. eventually settled to the bottom. I liked that mix, as it had a rich, dark color. Wish I had more.