Koa wood | Bluefiddle's West Wind Strings

September 30, 2015September 30, 2015

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.

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

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: 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: 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.

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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September 20, 2015

5 String Progress Report #12: Purfling

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Five String Fiddle Back Plate Purfling

Layout

I use the same purfling marker to begin the layout of the back purfling as I did on the front purfling, except that, as I have a habit of using a “signature” fleur-de-lis on the upper and lower ends of my five-string fiddles, I have to stop short of the corners and ends, and sketch those areas in by hand. However, I had noticed that, since I have literally been sketching them in by hand, no two were alike, and they were pretty time consuming. So, today I made a small template out of tag-board…a junk-mail offer for some thing or another, that just happened to arrive at the time I needed such a thing. (Serendipitous, that….)

I used the purfling marker to lay out everything except the corners and ends, then used the template by poking through it with a needle, to lay out the ends, and sketched in the corners with a pencil and knife.

purfling layout — Purfling layout: Upper end and corners, with template and needle.

Purfling layout: Lower end and corners, with template, needle and knife.

And, now I am ready to cut all my purfling grooves, pick them out, and begin installing purfling.

Back Purfling layout. — All back purfling laid out and ready to cut.

Cutting the groove and picking out the waste wood.

This part is hard on the hands. Some very good luthiers, today, now do this part using a dremel tool, but I tried it a couple of times and had some rather nasty accidents. I reverted to cutting the grooves by hand. It is hard on my hands, but I end up doing better work. I just have to take breaks now and then.

Something I had to bear in mind on this fiddle, is that the Koa grain is so curly and wild that I could have no confidence that the purfling pick would not chip out a larger piece than I intended. So, I had to move carefully, and take small “bites.”

Also, inlaying the “purfling-weave” (the fleurs-de-lis) was risky, as the graduation was already complete, so I did not have lots of extra wood to work with. I had to make sure I did not cut too deeply. I worked carefully, and took my time, and got through the challenge without mishap. Aggravated my arthritis somewhat, but that is OK, too; I will just take a break for a day and do some other things.

The chimney needed to be cleaned, and commercial cleaners refuse to do it, as they say our roof is so steep and high, that it is too dangerous. (sigh…) So we bought a set of chimney brushes, and, every year, we do it ourselves. That took a few hours Saturday morning. We heat with wood, and it is important to clean that chimney every year.

But in the afternoon and evening, I went back and got back to work on the fiddle. Section by section I sliced along those marks and cut the grooves as deep as I thought I needed them, then began picking out the wood from between the cuts.

Upper purfling groove, partly cleaned and nearly ready for the purfling strips.

Lower purfling groove. Ran out of energy, but this is all that was left to do. I’ll get it another day.

Back purfling groove, nearly complete. — Whole back, as it stands, now.

Anyway: I think that is about as far as I am going to get, this weekend. I will try to finish the purfling by Wednesday, get the heel and neck and scroll at the absolutely finished level, then start doing all the final edgework, and prepping for varnish.

Thanks for looking.

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September 13, 2015September 13, 2015

5-String Progress #10; arching the back plate

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Five String Progress #10: Arching

Completing the back plate arching

When I left off, last time, I was too tired to continue carving, so I took a break and completed other responsibilities for a few days. Saturday, I came back and spent some time carving and scraping:

Back arching done — Final outer carving complete–beginning scraping.

As you can see, the basic shape is complete. Scraping will be the method of moving wood from here on, on the outside… the inside is still a flat, rough plank. But I continued scraping for a while on the outside before beginning the inside.

Back plate with scrapers: I used the “shmoo”-shaped scraper to clean around the inner bout edges and the others to establish the final shape of the outer curves.

Once the plate is essentially the exact shape I want it, (checking with low-angle lights, etc.) I move to finer scrapers– sharpened at 90 degrees, and used gently, flexing the blade to match the curvature of the plate.

Final scraping: this is not to say that more scraping will not be done later, but that will be after the purfling is completed. This is about as far as I will go until then.

Beginning the inside arching and graduation

Now I can flip the plate over and begin carving out the inside of the back. Here is the cradle without the plate. Notice that the plywood cutout matches the shape of the plate fairly closely, while the thick pine board simply supports the plate while I am carving. The plywood is what holds it still, laterally. The spring clamps prevent the plate from flipping out of the cradle.

Working cradle for violins and five-string fiddles. The hollow shape allows the cradle to be used on both sides of the plate. The full-thickness cutout allows chips to drop through and not obstruct the work.

The back plate has already been marked for inside arching. I will have to monitor thickness constantly, but here it is, ready to carve:

Back plate ready for carving. Notice the lines mapping out the general shape to be “excavated.”

And, the “fun” begins again. This Koa wood is by far the most difficult wood I have ever used on a back…but it has to be done, so, chip by gouged-out chip, here we go:

Beginning the inside arching. — Beginning the inside arching, using a gouge again.

I will post again when I am ready to install purfling.

Thanks for looking.

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