Posts Tagged ‘sealer’

5-string report #15: Varnishing

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Five String Progress Report #15: Varnishing

Mineral Ground

I did not take any photos of this process…it only consisted of rubbing a gypsum suspension into the wood, all over, then rubbing it off, as completely as possible. The goal was to fill the wood pores, so as to limit the penetration of varnish into the wood. Apparently the varnish tends to dampen vibrations, and deaden the violin sound just a little. I don’t know how much effect it really has, but I got the idea from Roger Hargrave, who said it made a difference in his work. If it is good enough for him, I am game to try it. My suspicion is that my ears are no longer good enough to hear the difference, due to a lifetime of work in heavy steel. But…I have had very good reviews on the few instruments on which I have used the ground, so…either it really helps, or I have just improved my building skills, lately.

Sealer

My sealer is pretty simple: it is raw pine pitch dissolved in a combination of pure spirits of gum turpentine and alcohol. It penetrates pretty deeply, but the alcohol and turpentine (in that order) evaporate rapidly, and leave the pine resin in the wood. I rub off as much as I can of whatever is on the surface, and let it dry in the sun. Sometimes I have hung it up to dry indoors, but it does make the house smell of turpentine. My wife has very little sense of smell, and I don’t mind the smell, but others might, so I try to limit that sort of thing.

front with sealer

Front with sealer

 

Edge with sealer

Edge with sealer: notice the contrast between front and side. I hope to correct that, somewhat, with varnish.

 

Back with sealer.

Back with sealer. Still somewhat dull, but just wait until the varnishing begins!

 

hanging up to dry inside

Hanging up to dry inside.

 

Back drying inside

Back drying inside: I decided it was warm enough outside, so I moved it to the yard, and propped it in an old lawn chair.

 

Sealer drying in the sun:

Sealer drying in the sun: it was interesting to see that, as the wood warmed up, the sealer began to ooze back out of the pores, making tiny dots all over.

 

Varnish

Once the violin was very warm, and quite dry to the touch, I rubbed it down with a paper towel, to remove any residue, then coated the back with a yellow varnish, and the belly with a brown varnish. I hope to even out the color somewhat and diminish the sharp contrast between the dark, curly Koa and the nearly white Sitka Spruce.

First coat of varnish on the front

First coat of varnish on the front: makes quite a difference, doesn’t it?

 

one coat of varnish

There’s the whole fiddle in the sun, with one coat of varnish.

 

And...the back!

And…the back! Look how the curly Koa is catching the fire from the sun.

 

Koa Flame

Pretty serious flame in this curly koa wood! You can see why it was tough to carve.

 

Anyway, that is about as far as I expect to go, today. I may get another coat or two of varnish on there, this evening, but it will not be an appreciable visual difference until it is done. I expect to use at least another six coats before calling it complete.

Thanks for looking.

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5 String Report #14: Final Varnish Preparation

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Final Varnish Preparation:

Advance warning:

An apology in advance: as I warned some time ago, I have a tendency to get out of “photography mode” and just pursue the tasks at hand, then suddenly realize that I was supposed to be doing “show and tell”. So, (sigh…) this time it will be more “tell” than “show.” But I do have some photographs of the tools involved.

Cutting the Purfling Channel

The first step in cutting the channel is to determine its boundaries. I usually use a compass to scribe a line 1.6 mm in from the raw edge of the plate, all the way around, including the corners and the ends, where the channel has to follow the purfling away from the edge. (This time I used a special tool, made by Jake Jelley, to do the same thing. I think it worked better.)

Tool for scribing the crest of the edge

Tool for scribing the crest of the edge. There is a collet-style pencil lead held in place, there.

That marks the outer edge of the channel, as well as locating the crest of the finished edge. I extend that line at the same distance from the purfling at the ends, so, at the ends I have two lines: one forms the crest of the edge, the other the edge of the channel. The dark Koa wood did not easily show the pencil mark, so I had to scribe firmly, and usually several strokes.

I then cut the channel with a sharp gouge, trying to keep it shallow, but following the scribed line all the way around. I used a larger gouge for the upper and lower bouts: a smaller one for the C-bouts.

Larger gouge for upper and lower bouts.

Larger gouge for upper and lower bout channels.

 

Smaller gouge for c-bout channel

Smaller gouge for c-bout channels

Scraping the channel and fairing the curves

Then I used scrapers to “fair in” the channel with the curve of the arching, and make sure there are no humps or hollows.

Large radius scraper

Large radius scraper (this scraper has four edges…each a different curve.)

 

Small radius scraper

Small radius scraper

 

Smaller Radius scraper

Smaller radius scraper

 

Smallest radius scraper.

Smallest radius scraper. This one has a long flat edge, a long curved edge, and both ends have a very small radius.

 

Flat scraper for final fairing-in of curves.

Flat scraper for final fairing-in of curves.

Outer edgework

Finally, I use a tiny plane and a file to shape the outer edge, curving smoothly from the scribed “crest” to the outer edge, where, hopefully, it will smoothly join the curve from the inner edge.

Planing the outer edge curve.

Planing the outer edge curve.

 

Filing the outer curves smooth.

Filing the outer curves smooth.

 

Final Neck and Scroll-Work

I also double-check the scroll and neck shape and contours. They must be scraped to perfection before I can move on. I use a template (copied from Henry Strobel’s books) to check the upper and lower shape and size of the “handle” portion of the neck, and then try for smooth transitions between the two.

Neck template

Neck template for upper and lower neck cross-sectional shapes.

 

Upper neck shape

Upper neck shape with template.

 

Lower neck shape with template

Lower neck shape with template

 

Scraping the Volute

The volute has to be scraped in both directions, otherwise the scraper will simply follow the grain and leave humps. (Ask me how I know…)

 

Scraping the transverse curve in the volute.

Scraping the transverse curve in the volute.

Final Varnish Preparation

At last I am ready for final varnish preparation. Everything has to be as perfect as I can get it, because every imperfection will definitely show up under the varnish. The tiniest blemish will show up like a neon sign once I begin the varnishing. Some people insist on only using scrapers, but at this point I feel fine about using very fine (400-grit) abrasive paper to remove the tiny blemishes.

ready to varnish

Pretty much ready to varnish. Looks pretty plain at this point, doesn’t it?

I removed the fingerboard for varnishing…it was only temporarily glued in place, originally, to aid in the neck setting procedure. While varnish is drying, I will shape the underside of the fingerboard, and lighten it, to enhance tone and projection.

After the varnishing is completed, I will glue the fingerboard permanently in place. I will also install the saddle, nut and pegs after varnishing. At that point, the violin will be essentially complete, and set-up is all that remains.

So: I’m sorry I missed the “in progress” photo opportunities, but, from here on out, it will be just progress reports in finishing. The mineral ground is next, and then the sealer.

Thanks for looking.

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