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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2 Responses to “5 String Report #14: Final Varnish Preparation”
  1. Chris Hadfield
    10.05.2015

    nice job Chet, amazing the things you know. Chris


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