Almost all violins are made of maple and spruce. Spruce is used for the front of the instrument because it is light and strong and transmits the vibrations of the strings very well. Maple is used for the back, ribs and neck because it is stable, strong and beautiful. For some of the larger instruments, like violas and cellos, sometimes softer woods like poplar and willow are used for the back and ribs. Spruce from Italy (Picea abies) is highly prized by violin makers, as is Bosnian maple (Acer pseudoplatanus). I also use Engelmann Spruce (Picea engelmanni) from Canada.
I buy most of my wood from dealers who specialize in violin wood. Some of these dealers do the cutting themselves, and some of them import the wood from Europe. Dealers travel all around the country visiting violin makers and a few times a year one will pull up to my shop with a van full of wood. This is a good way to buy a few pieces at a time. When ordering a large quantity, such as an entire log, it can be helpful to travel directly to the wood cutters and have first choice of their best wood.
Selecting wood is mostly intuition and part science. I have to rely on my senses. The first impression I get from a piece of wood is the weight, I want just the right weight- definitely not too heavy but also not too light. It has to be cut well so that the grain is running straight through the piece. Sometimes I press my fingernail against the grain lines to gauge the hardness. I want it to have a certain crisp quality. How fine are the annual growth rings? I then check to see if I like the look of it. I may look through a hundred pieces of wood to find two that I like.
Then there is the question of how old the wood is. There is a certain fascination with old wood. Other woodworkers are only concerned with the moisture content of the wood, but wood goes through other changes as it ages. In spruce the resin in the wood will harden and crystallize as it ages, perhaps enhancing tone quality. Some dealers will tell you that the wood is old, but there is no real test to verify that claim. We do know that the old Italian masters were not overly concerned with old wood. Many of Del Gesu’s instruments were made with fairly fresh wood. Personally, I use wood that is at least 4-5 years old. I feel that this is enough time to dry and age, but I use older wood when I have it.