Cellulose nitrate (CN) 3

Spectroscopy chart CN

Powder bowl and lid in imitation of tortoiseshell, 1930s

CN

Source

MoDiP.

History

There is a residue of powder in the bowl suggesting that it was used.

Material

Entirely made from the featured material, cellulose nitrate.

Degradation

The lid is cracked. It has been formed into a shape that it finds difficult to hold. As time passes and the material becomes more brittle, cracks tend to spread.

The knob is going crystalline. This could be because of its higher density or as a result of contamination from being touched. The bottom of the bowl is glossier than the top and sides. The loss of shine is likely to be due to interaction with light and the result of handling.

 

Degradation typical of the material not visible in this example

It could smell of camphor.

Treatments

The damage cannot be reversed. The residue of the powder could be cleaned out with a dry swab.

Display and storage

Ideally, cellulose nitrate objects are kept in cooler (2 - 5°C) and dryer (20% - 30 % RH) conditions than other types of plastics to help slow down the degradation process. This object should be stored in a well-ventilated area and covered loosely with conservation grade acid free tissue paper or in a ventilated archival box. Ideally charcoal cloth would be placed inside the packaging of all cellulose nitrate objects to absorb volatile off gassing however it is expensive and needs to be changed regularly. For that reason you may decide to use it only for particularly degraded objects. It should be kept separate from other objects, especially those containing metal, to prevent any off-gassing affecting them. It should be checked every six months.

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