Cellulose nitrate (CN) 1

Spectroscopy chart CN

Stencil, 1960s

CN

Source

Donated by Paul Meara at the project's inaugural seminar.

History

The amount of pencil around the letters, suggests it has had a life of use before its donation to this project.

Material

Made entirely of the featured material, cellulose nitrate.

Degradation

Cellulose nitrate is a chemically unstable material. The stencil is warped along both axes. The top and bottom edges where the material is thickest have gone crystalline except at the ends and in the middle. Believed originally to have been clear and that the colour is a result of degradation.

 

Degradation typical of the material not visible in this example

Can become brittle and crack, and have acidic droplets; sometimes it smells of camphor.

Treatments

The pencil can be seen as a significant part of the object's history. However it could be cleaned off with an eraser however as the object is warped and brittle great care would need to be taken to support it underneath to prevent cracking.

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.

Cellulose nitrate 2 >