Everybody has a different technique for varnishing and there is a plethora of good varnishes to choose from. What I use is an oil varnish based on a recipe that Joseph Michelman wrote about in his 1946 book Violin Varnish. His varnish is too soft for my taste so for years I used to mix it 50/50 with International Luthiers Supplys Violin Oil Varnish. I still use a lot of their clear varnish to mix in for strength and to cover my edges.
The idea with the Michelman process is to take rosin and chemically convert it to a resin bonded with various metals. This is a dry substance he calls rosinate. This is soluble in turpentine. Linseed oil is added to that mixture to produce the varnish.
These days, I am mixing Joe Robsons concoctions (www.violinvarnish.com) with the Michelman varnish. Joe does the whole scary gum/turpentine/oil cooking process and makes up a variety of good oil varnishes which are probably similar to what was used 300 years ago.
52 grams gum rosin (ww grade) crushed to gravel consistency.
586.6 ml. distilled water with 13.3 ml. 45% KOH added.
Boil 5 minutes
Makes a murky soap water...
To 200 ml. of this I add 120 ml. of an AL/Ca solution.
This is made by adding 500 ml. of 5% Aluminum Chloride to 150 ml. of 5% Calcium Chloride.
Mix thoroughly then filter. I use an old cotton bed sheet ripped up in small pieces as a filter.
Wash the mixture three times with distilled water.
After all the water is drained, the mixture must be dried. I spread it out on a stainless cookie sheet and place it under a heat lamp overnight. In Alaska's low humidity, this is sufficient to dry it thoroughly. If there is water present the rosinate will not dissolve in turpentine. Fresh turpentine is also a good idea.
Its a good idea to read as much as you can before messing around with all these chemicals. Harry Wake has a good description of the Michelman varnish in his book The Techniques of Violin Making if you cant find the Michelman book.
Ready made varnishes are a good idea for a first attempt, and always try your formulas on a piece of scrap first!
OK, Here we go...
The cello has been in the light box for 7 days and has darkened nicely.
My next step is to put a bit of Ammonia in the water tin, close the door and let the fumes add more color and possibly neutralize some positive charge that builds up with the lights.
One hour is enough if I can stand the stink. I then vent the box to the garage.
I seal the instrument first with 5 grams rosinate, 30 ml. Trichloroethylene, and 20 ml. of International Luthier Supplys varnish. Trichloroethylene is deadly... note the gas mask. All the vents are turned on and there are open windows.
Heres the chemical area with the vent hood. There is also a sun light that I bought at a health store to help with SAD (Seasonal Affected Disorder). Its what we used to call Cabin Fever. Too dark... too long... ieeeagh!... going crazy!
The light is also useful for checking color with your varnish. Ive got incandescent, Halogen, Full Spectrum, and natural daylight at the window for reference. Varnish will look a different color in each light.
Heres the first coat with the sealer. I use Internationals clear violin varnish for the edges.
After drying in the box for about four hours, I put my first coat of varnish on.
4 grams rosinate
10 ml. turpentine
5 ml. linseed oil
It takes several hours to dissolve the rosinate in the turpentine. Then I add the linseed oil.
I also add a small bit of Lampblack to the concoction at this time, then mix the whole with an equal amount of Robson's Amber varnish.
Comes out pretty thick.
This is the back and ribs after this first coat of varnish. I now put the cello in the light box for a few days to dry before any more coats.
Two days later...
I first flatten the sealer coats with 320 open coat sandpaper. This knocks down all the dust motes and cat hairs and gives a fair surface to work with. I am not trying for a flat surface.
All the materials, the wood, the varnish, are organic, sculpted and three dimensional. This finish will not be flat, clean, even, uniform or anything resembling what comes out of the present day guitar factory. Different tradition, different techniques.
Sorry... some of my biases coming out. The plastic, freshly dipped look appalls me.
Back to the bench.
This is the color rosinate which is made slightly different from the clear rosinate. If you want the formula for that read the literature or e-mail me... email@example.com.
4 grams color rosinate
10 ml. Turpentine.
After several hours, the solids dissolve and I filter.
I also buy green coffee and roast my own... thats what the gadget in the background is for.
Ive already added 5 ml. Linseed oil and now add an equal portion of Joe Robsons dark concoction. This will not brush on easily...
It comes out thin and very dark.
Here is the back. Quite a lot of red there.
This is a process. Everything will be different when Im done.
I wasnt able to get a clean picture. Looking at the last two photos you can get an idea of what different lighting can do to color.
Ive wet sanded the cello lightly with 2400 grit Micro-mesh. Wonderful stuff. I needed to clean up a few runs and even the color on the top.
Heres the top. Maybe a close-up would have been better.
Wet sanding the back.
The next thing I do is glaze the top with oil pigments. It is a way of adding color without adding much thickness. I use Grumbacher Burnt Sienna and Burnt Umber mixed together.
I smear this pigment paste all over.
Then wipe most of it off with a paper towel.
Comb it out in the grain direction... or stipple. This means tapping the brush into the varnish surface to disperse the smear lines.
Im smearing the pigment into the surface with my hand at this point.
Here is the back and ribs after Schmutzing!! I still have four coats of varnish to go. Two color and two finish/polishing coats.
I try and get most of the color as close to the wood as possible.
Here is the scroll after the glazing.
I mixed a lighter and easier to use batch of color varnish using Robson's Garnet Rosin Varnish. After waiting three hours, I applied a coat. Tonight, after a Symphony rehearsal, I applied another coat.
I still have the two finish/polishing coats to go and maybe a little fun with pigments before Im done with the varnish process.
Three days later:
I wet sanded again with 2400 grit Micro-mesh.
Heres a picture after sanding. Theres no glare, so you can actually see something in the picture.
I decided to not do the fun with colors step. I havent done it with a cello. What it involves is removing color varnish with a rag dampened with ethyl alcohol, then applying various color dyes in a shellac base (Kremer Pigments). I take a bit of red, some blue, and yellow and start mixing to get shades of green, brown and purple. This is added in varying degrees to the artificial wear spots Ive created. Im adding dirt essentially. Dirt is not black... its green and brown and all the colors of the rainbow. This process for me is very subtle and not overdone.
Here are some examples of my last violin.
The upper bout, where the hand sometimes grabs has lost some varnish...
The lower back is a wear area, where the violin touches the shoulder. If you look close, can you see some green?
The upper back...
Heres a shot of the ribs on that violin. This is the same varnish that is on the cello after polishing out.
Back to the cello. Im mixing a fresh batch of polishing varnish. It is the same formula as my clear varnish that I added after the sealing coat.
Here I add a spot of lampblack. A historical perspective would be that every old instrument that went through the Industrial Revolution in Europe would have this ingredient in its varnish.
For example... here is a picture I took in 1982 from a riverboat on the Thames in London. They are steam cleaning a century of soot off the buildings along the river front.
Heres the first coat of the finishing varnish with...
the back receiving the treatment.
I let the last two coats dry four days before polishing out. This is two days into that. Im mixing some Burnt Umber Acrylic color with Lampblack to apply to the inside of the pegbox and the f-holes.
The f-holes... That varnish sure looks shiny. Ill fix that in a few days.
Heres the pegbox...
Its back into the light box for two more days.
Two days later... the varnish is now hard enough to polish out.
The light box is now shut down.
My first step is to wet sand with 3200 grit Micro-mesh.
The blue can has some fine grit Pumice powder that Ive had for years. The oil that I use is from International Luthiers Supply. The polishing pads are pieces of cut up felt.
I put a little oil on the felt. This is enough to rub the ribs and the scroll.
After rubbing the oil in, I sprinkle the pumice and start rubbing and polishing...
In this picture, Im polishing the edges with pumice.
Ive only put four coats of clear on the edges and havent sanded between any of those. Every time I put a coat of varnish on the top or back, Ive wiped the edges clean with my fingers. This varnish is pretty chippy. What Im trying to do is put the durable material on the edges which will receive the most wear. Perhaps I should use polyurethane.
The pumice and oil combination makes a polishing cake on the rag. I use this to buff the finish. Too much pumice will scratch the finish and wear through. Just enough will bring out a nice shine.
I used to go to the point where the light bulb showed up cleanly on the surface.
Lately, I have been going a bit farther with a traditional polishing technique involving just a rag and alcohol. I buy my 200 proof denatured ethyl alcohol from a chemical supply house because the Everclear in Alaska is now too diluted with water. I think its about 30% water.
Heres a picture of a top edge I was scraping earlier in the build to add character.
Polishing with alcohol. I fold a small cotton rag (hopefully lintless) and apply some Ethanol from my small container.
As in French Polishing, that rag cannot stop or it will bite into the finish. Circular swirling motion or figure eight motion... keep it moving.
This is an oil finish, but it is young and the alcohol will dissolve it. In several years, that probably wont happen.
Here are a couple pictures I took outside on the deck. This is taken with the sun coming from the left.
This has the sun coming from over my right shoulder, almost straight into the cello. Depending at what angle you are looking, you can see different colors in the finish... or maybe I just dont know how to adjust the white balance on my camera.
Here are the finished ribs.
Heres a picture of the back lower right corner that Ive shown quite a few times.
Here is a shot of the scroll.
the left f-hole and corner.
You can see part of my label here.
Now its time to hang it up and wait for the varnish to dry thoroughly before setting it up.
Ill be back in a couple of weeks with more news!