Skip to main content
Ingenium Logo

You are leaving IngeniumCanada.org

✖


This link leads to an external website that Ingenium does not control. Please read the third-party’s privacy policies before entering personal information or conducting a transaction on their site.

Have questions? Review our Privacy Statement

Vous quittez IngeniumCanada.org

✖


Ce lien mène à un site Web externe qu'Ingenium ne contrôle pas. Veuillez lire les politiques de confidentialité des tiers avant de partager des renseignements personnels ou d'effectuer une transaction sur leur site.

Questions? Consultez notre Énoncé de confidentialité

Ingenium The Channel

Langue

  • Français
Search Toggle

Menu des liens rapides

  • Ingenium Locations
  • Shop
  • Donate
  • Join
Menu

Main Navigation

  • Browse
    • Categories
    • Media Types
    • Boards
    • Featured Stories
  • About
    • About The Channel
    • Content Partners

The great imitator: Cellulose nitrate in the twentieth century

Share
5 m
Jun 11, 2020
Categories
Conservation
Categories
Engineering & Technology
Industrial Technology
Sciences
Media
Article
Profile picture for user Caitlin Walsh
By: Caitlin Walsh
Ingenium - Canada's Museums of Science and Innovation
Six small rulers from a drafting kit are presented on a white background.
Photo Credit
Caitlin Walsh
Six ivory rules

Popular culture often dramatically portrays cellulose nitrate materials as extremely flammable film, catching fire in projectors and exploding in a great blaze taking down buildings, as seen in Cinema Paradiso. What you may not know is that before cellulose nitrate was used to create film, it was originally called Celluloid — and had a different function.

Celluloid is cellulose nitrate with camphor added as a plasticiser, to make it — as you may guess — more plastic. It is known as the “great imitator” of ivory, tortoise shell, and horn, as it can be made to have similar appearance to these natural materials.

A handsome, wooden case sits open on a tabletop; inside the case is a royal blue lining and some old drawing instruments. The photo shows the artifact before its conservation treatment.
Photo Credit
Caitlin Walsh

This drawing kit was owned by Marcus Smith, a railway engineer for the Canadian Pacific Railway.

Celluloid is created by chemically modifying the cellulose molecule with strong nitric acid, and adding other acids, such as sulphuric acid, plasticizers and water. Depending on the amount of nitrogen added to the cellulose — called the degree of nitration — and plasticizers used, different types of materials are formed. For instance, cellulose nitrate film has a higher nitrate content than celluloid, and it is this higher nitrate content that makes the film so combustible.

Early celluloid objects

Most celluloid objects were manufactured between 1846 and 1950, starting in England by the Parkesine Co. in 1866, and then in 1870 in the United States. Popular objects created included imitation ivory and tortoise shell jewellery and vanity sets, collars, billiard balls, dolls, and tools.

Due to its lower cost and close imitation to natural goods, celluloid became a very popular material for people of all economic classes. As was claimed by the Celluloid Manufacturing Company, “[so] has celluloid given the elephant, the tortoise, and the coral insect a respite in their natural habitat”, celluloid was seen as a way to prevent wildlife decimation with industrialization around the world.

A case study of a drawing set in the Ingenium collection owned by Marcus Smith, a railway engineer, reveals a mix of both ivory and celluloid tools. Marcus Smith was born in Northumbria, England in 1815, and began his engineering career in 1844. After working on several railways in England, political revolution in Paris led Smith to travel to Canada in 1850, to work on the Great Western Railway. Following a long career with several different railways, Smith eventually worked with Sir Sandford Fleming on the Canadian Pacific Railway, eventually becoming Acting Chief Engineer between 1872 and 1878. Smith retired from public service in 1893; he passed away in Toronto in 1905.

A tray from an old drawing kit, composed of mahogany and blue velvet, holds drafting tools including three ivory handled pens.
Photo Credit
Caitlin Walsh

A tray from the drawing kit, showing three pens with ivory handles.

A close-up image of a glass slide with a small blob of white and blue liquid on the end; this is an example of a positive diphenylamine test.
Photo Credit
Caitlin Walsh

An example of a positive diphenylamine test, showing the sample turn a blue-violet colour.

Testing our artifacts

The photo above shows the different cellulose nitrate, ivory, and metal tools. The cellulose nitrate was identified through using diphenylamine tests, which react to the nitrates found in cellulose nitrate objects. A positive test is revealed by a blue-violet stain appearing nearly immediately if the sample is cellulose nitrate, and there will be no reaction if negative. The results for the test on this set of tools revealed there are six ivory rules and three ivory-handled pens. There was also a protractor, a sector and rule, and a cellulose nitrate pen with six cellulose nitrate pen nibs.

To Ingenium’s conservation staff, this result was quite interesting; it shows the use of both ivory tools and cellulose nitrate at the same time. It also shows how the object was a working object — one that was perhaps not purchased as is, but rather assembled for Smith’s purposes. His selection of tools evolved with the formation and availability of new, cheaper materials such as cellulose nitrate. This introduction of modern materials — the paving stone for future plastics — allowed for a cheaper alternative to luxury objects. This drawing set displays the use of ivory and celluloid tools simultaneously, at a time when the shift towards plastics was just beginning.

However, while cellulose nitrate was originally seen as a wonder plastic, it began to drop in popularity due to the instability of the material. There are several inherent sources of deterioration with cellulose nitrate, meaning that even without outside influences, the material will deteriorate by itself. These sources include the spontaneous deterioration of cellulose molecules, the varied quality of products used while formulating the cellulose nitrate, as well as the reversibility of the nitrate reaction, where nitric acid re-forms from the plastic.

Along with these inherent sources of deterioration, there are also outside effects which increase deterioration rates. This includes unfavourable temperature and relative humidity, as well as being exposed to visible and ultraviolet light. All these factors can increase the rate of which the cellulose nitrate deteriorates. In addition, once the deterioration reaction has begun, it cannot be stopped due to the self-catalytic nature of the reactions, but rather only slowed.

Three yellow-brown tools sit on a white background: a scale, a protractor, and a ruler.
Photo Credit
Caitlin Walsh

A cellulose nitrate scale, protractor, and rule were found in the drawing kit.

Six small rulers from a drafting kit are presented on a white background.
Photo Credit
Caitlin Walsh

Six ivory rules

Managing low-level deterioration of objects

How does this deterioration manifest in the object? The plasticizer used was generally camphor, which sublimates at room temperature. As the formative nitrate reaction reverses, the camphor migrates to the surface of the object, where it in turn evaporates. This reduces the molecular weight of the object, which causes cracks in the material’s surface, and causes the object to become brittle. Moisture in the air can then reach the cracks, which reacts with the nitrogen atoms in the object causing the formation of nitric acid. This is accelerated by the sulphur ions present in the cellulose nitrate, and the nitric acid then attacks the cellulose polymer chains, which causes continued damage to the object.

A series of orange rectangles depicts the various steps that are part of the degradation of plastic objects.

What does this mean for our conservation goals? As stated above, this reaction will happen naturally, but is accelerated by external variables such has humidity, temperature and light. With properly acclimatised storage, these chemical reactions can be reduced, and the deterioration slowed. At the new Ingenium Centre in Ottawa, a cool storage room is used for objects such as these. It has been shown that degradation rates can be slowed by half with a temperature decrease of 10⁰C. In other words, a plastic object will deteriorate half as quickly at 10⁰C than at 20⁰C. Further, keeping cellulose nitrate objects out of light, storing them in un-buffered acid-free boxes, and with in a low relative humidity environment will also slow adverse reactions. This means that while deterioration will continue at a low level, it can be managed so the objects can be preserved for years to come. 

Have more questions about the conservation of plastics? Connect with the Ingenium conservation team on Twitter @SciTechPreserv

Go Further

For more information on cellulose nitrate, and plastics in general, check out these books.

Shashoua, Y. (2008). Conservation of Plastics: Materials Science, Degradation and Preservation. Butterworth-Heinemann.

Waentig, F. (2009). Plastics in Art. Michael Imhof Verlag.

Tags
conservation, Collections Conservation Centre, Museum collections, heritage preservation, collections preservation, plastic, material science, cellulose nitrate
Author(s)
Profile picture for user Caitlin Walsh
Caitlin Walsh

Caitlin Walsh is a conservation intern with Ingenium. Upon completing her Applied Museum Studies degree, Caitlin plans on continuing a career in conservation through expanding her work experience and preparing for a future master’s degree.

More Stories by

Profile picture for user Caitlin Walsh
Caitlin Walsh
Ingenium - Canada's Museums of Science and Innovation
Three Conservators wearing personal protective equipment , including Tyvek suits, googles, nitrile gloves and respirators.

Behind the scenes of the Ingenium big move: Hazard mitigation of a print maker’s drawer

A small metal and glass prism and its old brown storage box sit on a white background. A Kodak color strip sits in front of the artifacts.

The science of artifact conservation: A prism and its leather case

A gloved hand holds up a sample sheet of colourful, rubber bicycle tires from Italy, circa the 1930s.

The science of artifact preservation: Cool storage solutions

Related Stories

Three images side by side, grocery shelves full of eggs in clear trays, coral reefs seen from space, and a map of Canada divided into four differently coloured shapes.

3 things you should know about egg refrigeration, coral reef satellite maps, and watersheds

Asbestos in mineral form. The mineral is greenish and white in colour and there are visible strands of asbestos fibres.

Artifacts and asbestos: Managing hazards at Ingenium

A three-part, spliced image of a parched and cracked area of soil, an atom encircled with electrons, and the surface of the Moon.

3 things you should know about salty soil, invisibility, and Canada’s lunar rover

Three Conservators wearing personal protective equipment , including Tyvek suits, googles, nitrile gloves and respirators.

Behind the scenes of the Ingenium big move: Hazard mitigation of a print maker’s drawer

Two museum conservators wearing full-body Personal Protective Equipment stand side by side, holding a black aircraft control panel upright. The artifact is sitting on plastic sheeting on a table.

Inside Ingenium’s smallest collections storage room

A black-and-white image shows a group of seven men standing behind a large piece of wood, which is painted with the call letters “G-CAAC.”

Saving the Curtiss HS-2L: Recovering a piece of history from the bottom of a lake

Over-the-shoulder shot of curator and conservator peering under the hood of the Electronic Sackbut synthesizer. Internal wiring and circuitry behind keyboard is exposed.

Uncovering the secrets of the world’s first synthesizer

A close-up photo of a grouping of glass bottles with handwritten labels, and filled with grain seeds. Small, printed yellow paper envelopes are laid out in front of the bottles.

Food for the future: How Canada's seed bank is protecting crop plants for tomorrow

A tiny bottle of water is held in two purple-gloved hands.

Messages in a bottle: Ancient water in the Ingenium collection

A spliced, horizontal image shows photos of a field of corn, the planet Mars, and an albatross flying over the water.

3 things you should know about fertilizer pollution, Mars, and the wandering albatross

A close up a burger patties, a diagram of the sun during the solstices and equinoxes, and a satellite image of the Milne Ice Shelf

3 things you should know about cell-based meat, the Autumnal Equinox, and Canada’s last ice shelf

A disassembled phone and a variety of parts and tools sit on a work bench.

My phone is blowing up! Dissecting technological artifacts for conservation treatment

Footer

About The Channel

The Channel

Contact Us

Ingenium
P.O. Box 9724, Station T
Ottawa ON K1G 5A3
Canada

613-991-3044
1-866-442-4416
contact@IngeniumCanada.org
  • Facebook
  • Instagram
  • Twitter
  • Channel

    • Channel Home
    • About the Channel
    • Content Partners
  • Visit

    • Online Resources for Science at Home
    • Canada Agriculture and Food Museum
    • Canada Aviation and Space Museum
    • Canada Science and Technology Museum
    • Ingenium Centre
  • Ingenium

    • Ingenium Home
    • About Ingenium
    • The Foundation
  • For Media

    • Newsroom
    • Awards

Connect with us

Subscribe to our newsletter to receive the latest Ingenium news straight to your inbox!

Sign Up

Legal Bits

Ingenium Privacy Statement

© 2023 Ingenium

Symbol of the Government of Canada
  • Browse
    • Categories
    • Media Types
    • Boards
    • Featured Stories
  • About
    • About The Channel
    • Content Partners