The long grain Young's modulus is a measure of the stiffness (in the direction of the grain) of a piece of wood.  The bars are the means (averages) of the measurements of many different samples and the lines are plus and minus one standard deviation.  The stiffness of the wood and its density are the two major material properties that determine the natural frequency of vibration of a sample of the wood.  In order to optimise the utilisation of a particular piece of wood in a guitar it is essential to have a good understanding of its stiffness.  I measure the stiffness of all the wood that I make into top and back panels.  Details on how these measurements were taken and how they are used can be found in the book.

RETURN