Autochromes Lumière

 

Deteriorations

Most of the deteriorations that an Autochrome are similar to those of the silver gelatino-bromide on glass; however, its multi-layered structure put the Autochrome at the risk of some specific deteriorations.

Breakage and Cracking
The most frequent deteriorations were of a physical order: breakage or cracking of the glass. Typically this was the result of mishandling rather than a fault in manufacturing. Once it was cracked, the whole plate. including the glass lining, was no longer watertight. Due to the coloured layer's extreme sensitivity to humidity. it was apt to quickly diffuse in the form of green spots accompanied by a general color alteration.

Separation of the Image
The flacking of the image from the glass plate was very frequent. Because it was in fact made up of a complex of materials, the Autochrome was the site of many internal tensions and occasionally, this would lead to the separation of a part or even the entire image. These detachments were generally localised to those places that were naturally at risk, such as at the edges of the plate, or were put a risk by mishandling, such as scratches or tears. Varnished plates were thus not often at risk, although improper storage could potentially damage any plate. Large and repeated changes in relative humidity could act on the emulsion, causing it dimensional change and flaking.

Light could also have a detrimental effect on dyes and the second varnish, which was made up of cellulose nitrate and was naturally unstable. This varnish could degrade quickly under prolonged exposure to light, including the light of a projector. In such a case case, micro-cracks appearing on the surface might then lead to a crack in the first varnish. Beyond these problems, other phenomena could also cause the image to delaminate: defective fabrication, inappropriate processing conditions, as well as the glass composition itself.

Mould
The most common biodeterioration are caused by mould. These molds are developing in a high relative humidity environment. It results in the destruction of the gelatin layer. If the autochrome plate was protected with another glass plate, the microenvironment within the two plates can even more conducive to the development of mould.

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