​​Making the arch on the viola is the most difficult job for a luthier.  It has the distinction of being the only task that requires you to work in three dimensions.  Perhaps carving the scroll is a bit of a three-dimensional affair, but to no-where-near the scale of the arch.  And it has virtually no bearing on sound.
 
Understanding three-dimensional shapes is something humans don’t seem to be adept at doing.  It stands to reason, though.  The organs we have to interpret spatial data don’t see in three dimensions.  Our eyes see two different two-dimensional pictures and then our brain extrapolates a third dimension.  Essentially, we guess what the third dimension really looks like.  Coincidentally, this interpretation by the brain is why artists are able to simulate a three dimensional space on a two dimensional canvas.  Our brains are unable to tell the difference between a fake and something real!
 
Poor conception or execution of the arch is devastating to sound quality, particularly in a Strad model instrument.  Conversely, arching well done will facilitate beautiful sounds for hundreds of years.
 
I try to develop the arch as a whole, working on the part least finished, but I find it useful to finalize (or very nearly so) the channel—the recurve around the perimeter of each plate.

This recurve takes the shape of my large gouge for the upper and lower bouts and a smaller gouge for the middle bouts.  The use of a smaller gouge for the middle bouts is probably an innovation of Stradivari’s. 
 
With finger planes, I work quickly to shape the viola.  Keeping the three-dimensional shape in my head is tiring. I finish the arching in one session while the image in my mind is fresh.

​What makes it more difficult is that there are parts of the arch, near the corners at the flanks, that you cannot see because other parts obstruct your view.  And the angles that let you see the arch don’t give a lot of information as to the shape.  These places also happen to be the most important to sound.  If properly shaped, they unite the middle, upper, and lower bouts and allow the three parts of the plate to function cohesively.
 
Because direct sight does not yield good information, less direct methods must be used.  I like to quickly run my fingers across these areas; a slight increase in pressure in the fingertips tells me it’s too full.
 
Shadows are also useful.  The clues are subtle, but you can tell when a shadow “catches” on a bump or high spot.

Using a combination of knives and this very small plane, the final outline is made.
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Shaping the outline is one of the great joys in violin making.  I am always surprised how quickly this goes.  I spend quite a long time imagining the shape and then before I know it, the job is done!

We shape and glue the middle bouts first.   The ribs are made to proper thickness, then bent around the iron.

​For these we use the traditional tying method.  I have yet to find a better method than this method used by Stradivarius.

​For the back and ribs I am using a domestic poplar.  I prefer poplar and willow for violas because of the distinct sound they create.  Poplar, compared to the more commonly used maple, is more flexible, softer and less dense. The first two qualities mean that poplar will produce a lower frequency when made to vibrate.  This makes an instrument sound richer and fuller in the lower registers.

Making a viola perform in its lower registers is the primary problem for both luthiers and players.  The most effective way to achieve a deep sound is to make the viola larger.  The giant violas of Gaspar da Salo are regarded as some of the best-sounding violas in existence, but very few players have the arm length required to play these instruments.  If we use poplar, we can shift the paradigm of sound lower without making the instrument too large.

Using a low-density wood will help reduce the total weight of the instrument.  Since a viola is much larger than a violin, and weight increases exponentially with size, violas can be quite heavy.  This viola will be significantly lighter than if it were made with maple – something any violist will appreciate.









​The top plate is traditional European Spruce (Picea Abies), which was used to make instruments even before the violin was invented.  As you can see from the photo, the piece is beautifully figured with what is called hazelfichte.  Hazelfichte provides good strength but not stiffness.  It will keep my options open for when I do the arching and graduations (thickness).  Because the wood is strong, I can more freely use shapes and thicknesses that promote movement and vibration.

-Jackson