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Wood's lamp: an essential tool for analyzing a painting?

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By Thibault de Watrigant4 min
30/12/20

Art Shortlist looks at the usefulness of the Wood's lamp to observe and appraise a painting. So is it a gadget without interest or a must have to examine a painting?


Summary

  • Its inventors and its different uses
  • The meanings of the colors produced by Wood's lamp
  • A sometimes indispensable tool to date and give paternity to a work of art


Its inventors and its different uses

A little historical reminder. In 1903, Mr. Robert Williams Wood invented a technique for producing ultraviolet light called "Wood's glass". The technique was rarely used in the early days, but resurfaced in 1925, when two French dermatologists named Deveze and Margarot used it to diagnose hair fungus.

Nowadays, Wood's lamp is used in many fields: graphology, mineralogy, in banking and financial institutions, in chemistry and in the field of art. In this article, we will try to understand the meanings of the elements that a Wood's lamp will highlight on your paintings. The aim here is not to establish a scientific report but to give you our conclusions acquired after several years of using this tool which has become indispensable for us.


The meanings of the colors produced by Wood's lamp

First of all, it should be noted that the first interest of Wood's lamp is to allow to see if the painting has been modified or repainted during its existence. In order to distinguish modifications on works, the lamp must be oriented towards fairly small areas and if darker areas appear, it is likely that the canvas has been completed since pigments overlap and superimpose. One must be careful, however, on this point. Indeed, some artists have particular techniques or have taken over paintings years later, so it is a fact to be handled with care.

Wood's lamp highlights the varnishes present on a painting. Depending on the colors that appear on the canvas, the conclusions are not the same. To differentiate an old varnish from a new one, it is necessary to consider that the old ones will appear with greenish and milky tints. Since old varnishes are composed of natural materials, it is difficult for a recent varnish to make an illusion. Modern varnishes will appear warmer, tending towards orange.


A sometimes indispensable tool to date and give paternity to a work of art

The ultraviolet rays produced by the Wood's lamp give precious indications on dating, provided that the expert knows the types of varnish, pigments and canvas used. This will make it possible to situate the work in time and even give it an author. To be as accurate as possible in your interpretation, you must take into consideration both the aesthetic elements at your disposal and what the lamp wants to show you on the canvas. In addition, complementary scientific analyses will allow you to refine the results of this expertise. 

Wood's lamp is above all an expert tool but it is interesting to make it known to as many people as possible in order to understand what results from it. This lamp is within the reach of all the purses, one finds some at the price of about twenty euros on Internet. Art Shortlist and its experts are at your disposal to appraise your works of art. To do so, you just have to request an expertise thanks to our dedicated form.