Measuring
The images from the µCT scans are true to size. Life-size prints can be used to reconstruct the rib outline or arching templates.
The high resolution of the µCT scans allows measurements at any point with an accuracy of 0.1 mm. For instance, thickness matrices of the plates can be created. Green numbers represent thicknesses of original wood, values printed in white indicate that the measuring point is positioned on a cleat or doubling and therefore does not represent the original dimension.
Thickness measurement of the back of a violin by Giuseppe Guarneri del Gesù. The pin-hole at the center of the back, typical for Guarneri’s instruments, is clearly visible.
We can take this even a step further and offer continuous thickness maps of bellies and backs of instruments. These maps provide a visual impression of the thickness distribution at one glance.
The back of a violin by Jacob Stainer has a conspicuous asymmetrical design. Clearly visible are a strip of parchment down the center-line, and Stainer’s label.
A completely different thickness distribution displays the back of an instrument by Giuseppe Guarneri del Gesù.
Underneath the parchment covering the center joint of the back of the violin by Jacob Stainer mentioned above, five marking points are hidden. Their distance from the lower end of the body can be measured precisely. To run a video of this procedure click here.
The resolution of the µCT scan is also sufficient to measure the width of individual annual rings for running a dendrochronological test.