Refining the Plates. Finishing the glue. Marquetry?

by | Jan 24, 2021 | Construction, Journal, Materials

This week I continued work on the plates, the back and top of the violin.

The Redwood top

The redwood is very light. I measured the specific gravity (density compared to that of water) at 0.27 which, compared to the 0.37 – 0.40 of the spruce that I normally work, with is very light. From handling redwood and working with it in other arenas ( such as building decks) I know that it is not particularly strong and cracks easily.

To make up for lack of inherent strength in the wood, I carved the plate with a fairly high arch and knew that I would be leaving it thick when I hollowed it out.

There are four things that I monitor when deciding how thick to leave the plate: The thickness in millimeters, the weight, the “tap tone” or note at which it rings when tapped, and the flexibility in my hands. There is a range for each of those measures, and it always ends up being a matter of compromise to balance them. With this redwood, which is so light and possibly weak, I decided to make the tap tone my main compass. I would leave the center for the arch, the part directly under the bridge, much thicker than usual and then thin the the upper and lower bouts, without regard to thickness, until the tap tone came out normal and the plate felt normal when I flexed it. This resulted in a plate that is about 40% thicker than usual, but that weighed and felt normal.

Given how crumbly and delicate the wood is, I was pleasantly surprised by a very nice finish it took from the scraper.

I placed and cut in the f-holes. I used a Stradivari type design which creates a short, broad, free platform between the f-holes. This design tends to make instruments that are a little less responsive and stiffer to play, but have a richer, thicker tone. With this light wood I don’t think that responsiveness is going to be an issue so I am concentrating on trying to get a fuller tone.

Using a template to locate the centers of the ‘eyes” of the f-holes. First I’ll cut two circles and then join then to form the f-hole

The top plate rings clear as a bell and sustains nicely when I tap it. The signs are that it is going to work well.

Next week I will add the bass bar and the top will be ready to go onto the ribs

The Applewood back

The specific gravity of the Apple wood is 0.6, which is at the high end of the range that I would normally consider usable for a back, so no special problems there. Having a slightly heavier back might be a good anchor for a possibly skittish top.

The arch of the plate is a convex curve that drops off gradually from the high point under the bridge. As the arch approaches the margins of the plate it might straighten out or even reverse into a concave curve, to form a “channel” around the plate edge. The exact shape and blending of these two curves has tonal effects on the finished instrument. In general the more the recurve, the more tendency toward a stiffer, but sweeter toned, instrument.

The finished arch showing the channel around the margins. The edges of the plate are still rough, they will be finished later, after the purfling has been fitted.

Marquetry

I am not a huge fan of decorated violins- they are sometimes attractive, but on the whole I think that the violin is a beautiful thing that doesn’t need any extra bling. Also, once you have seen a few violins and got your eye in, each violin appears as individual as a person, and doesn’t need anything extra to distinguish it. So why consider decorating the Redwood Violin? Three main reasons. I would like the violin to:

  • Be easily identifiable, even by people who have only seen a few instruments
  • Be uniquely Sonoma County. Decorative images give an opportunity to say something about our County
  • Showcase the work of other craftspeople in the County

Having seen recent impressive marquetry by my friends Greg Zall and Mark Tindley, I asked if they would like to be further involved in the project. They very enthusiastically embraced the idea, though with some of the same reservations that I have about possibly gilding the lily.

Mark dropped by at my shop this week to discuss the idea. There are some technical difficulties: Marquetry is normally done on flat surfaces, so the compound curves of a violin’s arch could make it difficult to drop in a pieced wood design without blowing the glue joints apart. Secondly, they normally work with thick veneers of between 1-2 mm. Parts of the back of the violin may be only 2 mm thick, so they will have to work with thinner materials. Mark seemed to relish these challenges and also the stipulation that all of the different colored woods that they use should come from Sonoma County.

Rejected landscape inlay idea

The biggest problem is of what design to use. We want something that is relevant to Sonoma County. One of my first thoughts was to create a landscape with receding hilltops and redwood groves, rising from a morning mist. Which to me such is quintessentially Sonoma. Mark told me that in general marquetry landscapes are very difficult to pull off successfully. A little search on the internet convinced me that he is right. With a few outstanding exceptions, they tend to look like badly rendered paintings. I think that the problem is that a pieced-wood design inherently has hard edged lines and lacks the subtle shading, blending and ambiguities that can draw you into a painted landscape. Marquetry is better suited to more graphic images

At this point I bowed to their experience, I handed the violin back over to Mark and will wait to see what practical and creative possibilities they suggest

Glue

A sheet of newly gelled glue

I finished my second batch of tendon glue. I had learned a lot from my first efforts and produced a very much improved, professional looking product. Form 1,800 grams (4lbs) of beef ankles I got 350 grams of tendons which, after 108 hours of cooking, yielded 200 grams (7oz) of quality, dried glue. Easily enough to finish the violin and several more instruments.

I’m very pleased with this part of the project. I will write a post about the process, including a recipe for those of you who want to try this at home. Meanwhile you can watch this video summary of this weeks work .


Purfling Dye

I heard from natural dyer Marilyn Buss that, after many experiments, she has successfully made a dark brown dye from locally harvested carbon ball mushrooms . I’ve sent Marilyn thick shavings of box elder that will be used to make the black and white purfling that edge the violin plates. This is very exciting and I’m looking forward to meeting Marilyn and hearing about the dye process.