Varnish Sequence

Varnishing Process:

All Smoothing and Varnish-prep is done:

When I last posted, the final woodwork had been completed. I had twice wetted down the wood, to raise the grain, and scraped and sanded away the rough raised grain. The wood was stable enough to commence the tanning process.

After the wood is smooth, there will be:

    1. a tanning treatment,
    2. a mineral ground treatment,
    3. a sealer, to lock the mineral ground in place, and
    4. finally, the varnish itself in a series of 6-12 coats, depending on color.

Tanning the Wood

People who live in very sunny regions (New Mexico, for instance) need no light booth: they simply hang their instrument out in the sun for a few hours and it takes on a deep yellow-tan color. I live in Oregon. Western Oregon, between Portland and the coast. We are more likely to achieve a patina of bird-droppings than a sun-tan, if we hang instruments outdoors. (Sigh…)

So, a number of years ago, I bought an old cabinet, about seven feet tall, lined it with aluminum foil as a reflector, wired it with a strong UV source (two 48″ fluorescent UV tubes in a shop-light fixture), and I hang my instruments in it overnight. To heighten the effect, I brush on a coat of very diluted Sodium nitrite and let it dry before I expose it to the UV. This works pretty well, and I have pretty much adopted it as a normal pre-varnish treatment.

tanned front of 16-1/2" 5-string viola
Tanned front side of the 16-1/2″ five-string Viola.

 

Five String Viola tanned back side
Tanned back side of the same instrument.

Mineral Ground:

Years ago, an excellent luthier in Europe posted a detailed explanation of why and how he employs a mineral ground in his instruments, to improve projection. I tried it (because, “if it is good enough for Roger Hargraves…”) and immediately started getting better reviews on the sound of my instruments.

So…obviously, that became part of my process, as well. I use gypsum powder, suspended in coffee (gotta wake up the tone!) so as to achieve a little deeper color in the same move. I rub it in vigorously, trying to get the particles of gypsum to actually penetrate the pores of the wood, then rub off the excess with a rag, before it is fully dry.  When it is dry, it obscures the grain, and turns a chalky white color.

Mineral ground drying on 16-1/2
Mineral ground drying on 16-1/2″ 5-string Viola. (5-string bass beginning in background.)

 

Mineral Ground is dry.
Mineral Ground is dry. I will sand off any excess mineral, and then apply the sealer.

 

Sealer

Five String Viola with Sealer coat, front view.
Sealer coat, front view.

 

Sealer coat, back view.
Sealer coat, back view.

 

The sealer, in this case, is simply rosin, dissolved in turpentine and alcohol. The mixture soaks into the wood, causing the mineral ground to become transparent, then the solvents evaporate, leaving the rosin in the wood. The mineral ground will never again be visible.

 

Varnish Beginning

When the sealer is dry, I sand lightly, using 320 grit, to remove any lumps I may not have seen, and then I am ready to begin varnishing. I always begin with two base-coats of very yellow/gold varnish, so that the gold color will shine through the darker color coats.

Five String Viola with Two coats of yellow varnish, side and front view.
Two coats of yellow varnish, side and front view.

 

Five String Viola with Two coats of yellow varnish, back view.
Two coats of yellow varnish, back view.

I like the way the European Maple and Spruce are shining through the varnish. I think they will sound great, too. Tapping on the corpus, it sounds as though it will have a big, deep voice.

I will follow the completion of the varnish process in a later post.

 

Thanks for looking.

 

Beginning the Varnishing Process

Varnish Procedure For a 15″ Five-String Viola

First things first: Mineral Ground

The raw wood is quite porous, and would soak up varnish like a sponge…which would dampen the sound. So we don’t want that to happen! The solution to the problem seems to be to fill the pores of the wood with very fine particles of mineral of some sort. I don’t particularly want something that would form a concretion, as some makers have done, because I think that also changes the sound, but in a different way.

I used Gypsum, ground very fine in a mortar, then suspended in water, and daubed onto the surface; then vigorously rubbed into the pores. After rubbing the mineral into the entire surface (except the “handle” area of the neck) I used a damp cloth to rub all the excess gypsum back off. While it is wet, it just looks like wet wood, but as it dries, it turns chalk-white, assuring me that the surface is truly saturated with the particles.

Partially dry mineral ground, front side.
Partially dry mineral ground, front side.

 

Partially dry mineral ground, back side.
Partially dry mineral ground, back side.

 

Then, after the gypsum suspension is completely dry, I use fine sandpaper to remove any excess mineral from the surface, so that there are no thick patches of mineral.

Dry Mineral ground, rubbed clean.
Dry Mineral ground, rubbed clean.

 

Locking the mineral ground in the wood: Sealer

As you can see in the above photograph, the mineral is still saturating the surface, and obscuring the grain. However, when I apply the sealer (in this case, a mixture of rosin, turpentine, and alcohol) the mineral ground will become completely transparent, and will permanently disappear. The varnish will then be free to show off the grain of the wood.

Front side with sealer.
Front side with sealer.

 

Side with sealer.
Side with sealer.

 

Back with sealer.
Back with sealer.

 

Making it Shine: Beginning the varnish

It takes a while for the sealer to dry, because of the turpentine content, but as it dries, the alcohol evaporates first, then the turpentine, leaving the rosin in the wood (which is where rosin comes from in the first place, of course) locking the gypsum particles in place. and further sealing the wood against saturation with varnish.

Before proceeding to the varnish, I carefully sanded all over, to clean up any spots that still felt rough or sticky, then wiped the entire instrument down with alcohol to remove any rosin residue from the surface.

Then I applied a first coat of yellow varnish, as I have noticed that many of the old instruments seem to have something yellow under the darker red or brown varnish. You can especially see it in the areas where the colored varnish has worn thin, or is completely gone. (Not all of them have this color, but I like it, so that is what I have chosen to do.)

So, here is the base coat of yellow varnish:

Base coat of yellow varnish on front side.
Base coat of yellow varnish on front side.

 

Base coat of yellow varnish on the side.
Base coat of yellow varnish on the side.

 

Base coat of yellow varnish on the back side.
Base coat of yellow varnish on the back side. The grain of the spalted maple is showing better, again.

 

Base coat of yellow varnish on scroll and neck heel.
Base coat of yellow varnish on scroll and neck heel.

 

I do not apply varnish to the “handle” portion of the neck until everything else is completely done. After everything else is done, including set-up, I will rub down the handle area with 400-grit abrasive one last time, and then put about a dime-sized dot of shellac on a rag, on the end of my finger, and vigorously rub it into the wood of the handle area, until it is completely dry. This somewhat seals the wood against sweat and dirt, without leaving a heavy, “slick” coating that would cause drag on a player’s hand.

The rest of the varnish coats will be building color toward the final look of the instrument. I will include them in another post.

 

Thanks for looking.

 

Commissioned 5-String Varnish Progress

Varnish Progress on the Commissioned 5-String Fiddle

Varnish Procedure for All my Instruments:

  1. Complete all scraping, shaping and smoothing: varnish preparation.
  2. Wet the instrument down to raise the grain, then
  3. Lightly sand with fine-grit abrasive, to remove rough bits of raised wood.
  4. Rub in a mineral ground, then use a rag to remove excess.
  5. After the ground dries, sand lightly again, to remove any rough excess mineral.
  6. Seal using turpentine and rosin.
  7. After the sealer is dry, begin adding coats of varnish.

Following the above format, here are the results:

Dried Mineral Ground, on the Five-String Fiddle, compared with varnished instruments.
Dried Mineral Ground, compared with varnished instruments.

 

Five-String Fiddle front view with sealer
Front view with sealer…mineral has disappeared.

 

Five-String Fiddle Side view with sealer
Side view with sealer…the grain is visible; the ground is transparent.

 

Five-String Fiddle back with sealer
Back with sealer; the grain is very visible, the ground has disappeared.

 

Now the varnishing begins!

The mineral ground was intended to close all the open pores in the wood so that the varnish will not saturate the wood. Then the sealer locks the mineral ground in place and causes it to become transparent. (Think “wet t-shirt material.” White stuff becomes transparent when wet, as a rule.)

So, now the varnish further seals the wood and begins to add gloss and protection from moisture, dirt, etc. And, if we do it correctly, it will add the color we want, as well, without losing transparency.

I have used both oil varnishes and spirit varnishes. I believe the old masters used oil varnish, but currently, I have moved to spirit varnish. Perhaps one day I will use oil varnishes again

Spirit varnish dries so rapidly that I can usually apply four coats of varnish the first day. So here is the fiddle with four coats of spirit varnish:

Five-String Fiddle with four coats varnish front view
Front, with four coats varnish…still pretty yellow.

 

Five-String Fiddle side with four coats varnish
Bass side with four coats of varnish: Too much contrast between side and front plate.

 

Five-String Fiddle back plate with four coats of varnish
Back plate with four coats of varnish… looking pretty nice!

 

Leveling the varnish

So, then, after the first few coats have dried hard,  we sand lightly to remove brush marks, sags, drips, etc. and begin to add color coats. Usually, I have a pattern of shading I use, to emulate light “wear” patterns. This one has very little of that.

Five-String Fiddle Final color front plate
Final color front plate…the light patch on the upper left is a reflection.

 

Five-String Fiddle Final color treble side
Final color treble side: notice that the front and side match nicely, now.

 

Five-String Fiddle Final color bass side
Final color bass side.

 

Five-String Fiddle Final color back plate
Final color back plate.

 

Five-String Fiddle Final color bass side scroll
Final color bass side scroll.

 

Five-String Fiddle Final color treble side scroll
Final color treble side scroll.

 

Final Finish Work

So, now we will let the varnish thoroughly dry, and harden; after which there may be retouching and minor changes to make, but the main focus will become set-up after that. (In case anyone is interested, the customer has been kept abreast of every step in the build, and is getting quite anxious to take possession.)  🙂

Thanks for looking!