While on the topic of the sufferings of rental instruments: When we started a rental program, a friend warned me that I’d regret renting cellos. Here’s one reason why. These babies cost a lot of money, but not enough to justify fixing something like this. I once repaired a fine old English cello that someone had backed a van over, and it wasn’t this bad.
I recently showed a violin getting a breast patch. Here’s a shot of that same top, prepared for making a plaster cast. The top has been spot tacked to a sheet of plywood, then a sheet of very thin latex stretched over it to protect it. Next a dam is built around the outside, to contain the plaster. The next step after this photo is to cut a piece of hardware cloth (something that’s a bit like window screen of thicker wire with bigger holes) to the shape of the violin top. Plaster gets mixed and poured over the top. After it starts to thicken a bit, the hardware (wire) cloth is pushed down into the plaster a half-inch deep or so, to hold the plaster in one piece in case it breaks for some reason (something I have never seen happen by the way). Then a backing bed of wood is pressed into the plaster surface, for taking the pressure of clamps. In less than an hour the plaster will have hardened enough to separate it from the top, and then it has to dry and harden for a week or so before it can be used.
A top cast has two main uses. One is as a perfectly–fit counterpart to clamp against when doing interior repairs. Examples are patches in the top, gluing new underedges to thicken an edge, or fitting a bass bar. The other purpose is to reshape a distorted top: a cast is made, then corrected in small increments, clamping the top in under a warm, damp sandbag to reshape it through a series of tiny changes until the distortion is removed. This is a gradual, gentle process that can take several months.
You’ll notice some bits of folded paper towel jammed between some of the separate piece of the form. You wouldn’t believe how thin of a hole wet plaster can slip through. As neatly as I try to work, usually some small part of the shop floor ends up with a fresh coat of whitewash.
Usually tops and backs are just glued directly to the ribs and linings, nothing fancy. At various places and times in the past, though, sometimes makers locked the top and back in place. This is seen in very old French violins and Dutch, also, but usually just as a thin groove slotted into the back or top, the width of the rib thickness, into which the rib is glued. Though this is mostly hidden, there are two nearly invisible clues that a back has the ribs set in. The first is that in spite of their great age, the margins of these backs and tops are usually flawlessly even all around. Where normal ribs can move and bulge, ribs set in a groove can’t. The other clue is to look at the back and rib junction right at the tops of the corners–the area in the photo above. Usually the fit isn’t perfect right at the point and a bit of the groove will commonly be visible there. You can see in this photo how that spot would be easily visible on this corner. While you’re noticing things, observe how the shape of the corner blocks was cut after the blocks were in place: you can see the arc-shaped cuts in the back that the gouge made in the process of shaping the blocks in place!
In this Dutch violin the maker has taken it one step farther, cutting a ramp with some unusual characteristics.
First, in gluing on the plates notice how the ramp routes the rib automatically, sliding it out to the upright cut. Second, just to make sure it doesn’t come apart, the maker has undercut the outside upright cut so that the rib curls outward in the groove and locks itself in place. This undercut warps the edge of the rib, resulting in a flange that locks into the groove’s undercut, as you can see along the top edge of the rib in the photo below:
Now, referring back to the opening photo, try to imagine what the lining, just inside the rib, is sitting on–a slanted ramp. In this violin the lining was not fit to the slope of the ramp. All it was doing was covering a puddle of glue hidden under the lining. Because of the undercut flange, this didn’t matter, and the rib was well held in place.
The only reason I had to see any of this was that the edge in the lower bout had been worn down from the outside to the bottom of the slanted groove by the players shoulder and was falling off. The back and rib had to be separated to repair this edge.
Sometimes a violin’s arching is vulnerably flat, perhaps the wood is weak, or thin, or a combination of those, and the center under the bridge starts to collapse. Often this is accompanied by the top puffing up under the board and the tailpiece, towards the ends. In such a situation, the arching is first corrected back to the way it originally was made, and then often some sort of reinforcement is put in. On this violin from the mid 1700s the collapse had caused a crack, and there were several other problems.
The first step here was to make a plaster mold (cast), then reshape the mold through several generations of corrections of the mold and the top. Then when the arch was back to a proper shape, I put in a very thin patch to hold the arching in place. That’s the patch in the center that’s being thinned in this photo. In this case, the upper area around the top block needed correction and reinforcement, and you can see the finished patch in place there, up towards the neck area. The final thickness of these two patches was only around 0.5mm–just enough to do the job!
Here’s a repair! I guess someone felt that a shim was needed under the board. I’m not even sure what the fix was supposed to be fixing. From this view, outside, I couldn’t see what I was looking at. Removing the board, I found a spruce shim of sorts.
I still don’t know what the mess on the edges was or was supposed to look like, but it sort of resembled a strip of purfling made with black layers of unbelievably filthy glue on either side of the spruce core. It’s all gone now!
Studs are used behind cracks to provide reinforcement. If the crack was a clean one, and properly glued, they may not even be necessary. I bet you could remove half of these, though, and not miss them.