ECR Casebook: High levels of carbon in printer's ink illuminated through the back of a violin at 850nm.
Violin by Jack Lott, c.1860 | Benjamin Hebbert.
Of interest, we can see that the printer's ink used to make the copy of a Stradivari label has a very high carbon content. Variations in the thickness of ink show that this was printed from moveable type in a form of makeshift printing press, with issues of over inking, and possible movement of the print type. We can also see the ribs of the laid paper. Jack Lott made some very convincing imitations of Stradivari and del Gesù labels, of which this is an example.
Infrared light is absorbed by carbon, and therefore it shows up strongly in this near X-Ray IR illumination at 850nm with the light source shining through the back of the instrument. The 1716 date is legible in ordinary light conditions, but does not show up here. The grey version is digitally filtered for clarity.