18th Century italian violin makers used the resin for violin varnish , and it continues to be used for that purpose .
18世纪意大利小提琴制造商使用了树脂清漆小提琴,后来它仍然被用于这一目的。
Dendrochronology establishes the age and provenance of the wood ; three-dimensional x-rays show up exactly how thick and dense it is , millimetre by millimetre ; and spectrometers reveal the composition of the varnish .
Using infrared technology , they detected a lush tuscan landscape - the same as in leonardo 's original - hiding beneath the coat of black varnish that had been added probably in the 18th century and obscured the original background .
The newly-restored copy , with its gleaming landscape in the background and sharp lines defining the spindle of the chair and the ruffle of the bodice , fills in details obscured by the yellowing varnish on the real mona lisa .
Walking around the plant , the smell of wood and varnish hangs in the air , the noise of sawing and drilling mingling with the resonant sound of hammers striking strings , and instruments being tuned over and over again .