1851: Ebonite - The Birth of the Plastics Industry?
Alan Dronsfield

This year marks the 150th anniversary of an important milestone in the early history of the plastics industry. This author, reader in chemical sciences at the University of Derby, looks at the events which culminated in the discovery of ebonite, arguably the world's first plastics material.

Plastics were around before 1851, as any collector knows, although they have only really become commonplace in the last fifty years. Before 1851 we had natural plastics substances which could be softened by heat and then moulded. Typical were horn (used, for instance, as 'windows' in lanterns and for making snuffboxes); tortoiseshell (the shell of the hawksbill turtle, used to make combs, dressing-tableware, etc.) and shellac, the secretion of the lac insect, Coccus lacca. This last material is, like the others, thermoplastic but, lacking any fibrous nature, it was initially only used for seals and medallions. When it was found that its inherent crumbliness could be prevented by the use of fillers, its uses increased. Readers will recollect Ron Copleston's description of 78 rev/min records (shellac, filled with powdered slate) in the Summer 2000 issue of plastiquarian (no. 24)

Intriguingly, one of today's most common plastics has a history going back to 1839, when Eduard Simon noticed that pure styrene was converted into a glassy solid, simply on standing. The product, named styrol or metastyrol, did not attract much in the way of attention for almost a hundred years: commercial production of polystyrene began only in 1938.

However, it was the discovery of the 'semi-synthetics' that started the plastics industry. Naturally occurring materials could be chemically treated to yield products which were thermoplastic, mouldable and capable of carrying an impression derived from the mould. Decorative items would no longer remain the preserve of the hand-carver, and laboriously constructed, intricate and expensive items would no longer be the preserve of the rich. From the latter half of the nineteenth century they would be stamped out from a mould: rapid, reproducible, but above all, cheap.

So, the industry started with the semi-synthetics. But chronologically one early plastics material surfaces before our 1851 landmark date. In 1846 Christian Schonbein discovered that cellulose could be modified by means of a nitrating mixture of nitric and sulphuric acids. However the product, cellulose nitrate, later named Celluloid, was only exploited (by Alexander Parkes) from 1860.

Enter ebonite
The author of many textbooks on plastics, John Brydson, contends that today's plastics industry really started 150 years ago with Nelson Goodyear's 1851 patent to produce hardened rubber, later called ebonite or vulcanite. (A longer list of alternative tradenames appears at the end of this article - Ed.) He suggests that the discovery of ebonite is usually considered a milestone in the history of the rubber industry Its importance in the history of plastics, of which it is obviously one, is generally neglected. Its significance lies in the fact that ebonite was the first significant plastic to be prepared and also the first plastic material which involved a distinct modification of a natural material.

The story starts with natural rubber. Europeans first reported it in 1521, when explorers observed Mexican natives using it in ball games. Its chemical history only really starts from 1736 when the explorer and naturalist, Charles Marie de la Condamine, exported from the Amazon basin to France some of the material which he had named caoutchouc (from the American Indian word for 'the tree which weeps', a descriptive reference to the means whereby it was collected). In its natural state, its uses in Europe were limited: mainly for pencil rubbers and in the fabrication of balloons (although Amazonian natives had a thriving and diverse rubber technology - Ed.) It had three drawbacks, which limited further exploitation. it became sticky in hot weather and rigid in the cold. Furthermore it was dissolved by a range of oils and greases and (slowly) degraded and putrefied even by the oils in sweat. One of the earliest attempts to deal with the ,stickiness' problem was to dissolve it in naphtha (a cheaply available solvent obtained as a by-product from the manufacture of coal gas), spread it on a flat table and allow the solvent to evaporate leaving a thin film of rubber. This was hand stitched between two pieces of cloth to yield a waterproof fabric sandwich. The discovery is associated with Charles Macintosh (from 1823) and today's lightweight, waterproof coats, of whatever manufacture, are still called 'macs' or 'macks'.

Rubber, with its intriguing elastic nature, was seen by many scientists and entrepreneurs to have distinct potential for commercial exploitation, if only its drawbacks could be overcome. Early attempts to modify its properties included heating it in a primitive pressure cooker (1768) to yield a horn-like resinous product and (in 1781) heating it with concentrated sulphuric acid which again gave a horn-like material, but in neither case was the result followed up. The dramatic change occurred with the use of sulphur to modify the properties of natural rubber. The use of elemental sulphur in this connection can be traced back to Erhard Leuchs who, in 1831, dissolved rubber in turpentine, mixed it with sulphur and heated the mixture to obtain a black, porous coal-like material. From its description this was clearly ebonite, though its potential remained unrecognised. In 1832, Friedrich Ludersdorff produced balloons lacking their usual stickiness by dipping his moulds into a solution of rubber and sulphur dissolved in turpentine. Jan van Geun extended Ludersdorff's method in 1837 by heat treating the films of rubber thus produced. His was the first description of today's vulcanised rubber, which he used as a lining for fire hoses.

Charles Goodyear in America was also working on the problem of making rubber more tractable. His early (1836) attempts used nitric acid fumes, but the method was not a great success. Two years later he met Nathaniel Hayward who was experimenting with sulphur. He dusted a sheet of natural rubber with finely powdered sulphur and exposed it to sunlight. The process yielded a thin film with reduced stickiness. Goodyear himself then began to experiment with the rubber/sulphur mixture (also containing white lead in his crucial experiment of 1839). He found that when a film made from this mixture was heated before an open fire, the hottest part at the centre became charred. But towards the edge there was a ring of rubber, cured, not sticky and yet remaining flexible and elastic. Rubber, as we use it today, had been invented.

But what of our founding plastics material, ebonite, and its date of 1851? Discounting Leuch's work, some of the credit for its manufacture must to go to Goodyear's British competitor, Thomas Hancock. He patented, in 1843, a process whereby heating rubber and sulphur together at about 155'C for two hours gave a horn-like solid containing 30% sulphur. Despite this prior claim, most of the credit for founding the plastics industry seems to go to Nelson Goodyear, Charles's brother, who in 1851 was awarded a patent for Improvement in the Manufacture of Indian Rubber. Essentially this is a reworking of the Hancock method so it can fairly be asked why most of the credit seems to go to Goodyear. Two reasons support the attaching of Goodyear's name to the invention. Firstly he clearly saw the potential of his methods for producing moulded articles '... into any desired shape for the purposes of being used in the manufacture of such articles, as the same may be applicable to'. But again Hancock appears to have got there first and in 1846 patented his suggestion that his hardened rubber could be used for making moulds for softer rubber articles. Almost certainly, the reason why the Goodyear brothers, ebonite and 1851 go together is due to the Great Exhibition of 1851 in London. Ebonite goods received enormous publicity. They exhibited a suite of rooms constructed of ebonite, including handsome mouldings. The rooms were furnished with chairs, bureaux and desks made of wood, but covered with ebonite veneers. Many, many articles including combs, buttons and knife handles all made from ebonite were on view. Despite the sombreness of the display, the public's imagination was captivated. Ebonite had come to stay, and the rest is history. The plastics industry had been born!

Readers wishing to follow up the story of the discovery of ebonite are directed to A History of the Rubber Industry, edited by P Schidrowitz and T R Dawson, published by W Heffer and Sons Ltd in 1952. Long out of print, this excellent and erudite book may be available through inter-library loan.

Acknowledgement
This article is a shortened version of one that is due to appear in Education in Chemistry later in 2001 (co-authors TM Brown and PJT Morris). We are grateful to the editor of this journal for granting permission to condense the material for use in Plastiquarian.

The illustrations to the article are from the Katz collection.

The following list of alternative tradenames for ebonite/vulcanite is taken from Classic Plastics by Sylvia Katz, to whom our thanks:

Ace - American Hard Rubber Co., USA
Super-Ace - American Hard Rubber Co., USA
Amcosite - Siemens Bros. & Co., UK
Bulwark - Redfern's Rubber Works, UK
Cohardite - Connecticut Hard Rubber Co., USA
Dexonite - Dexine Ltd., UK Endurance American Hard Rubber Co., USA
Gallia-Rubber - French ebonite
Keramot - Siemens Bros. & Co., UK
Level Chuck - American Hard Rubber Co., USA
Luzerne - Luzerne Rubber, USA
Mercury - American Hard Rubber Co., USA
Navy - American Hard Rubber Co., USA
Onazote - Expanded Rubber Co., UK
Permcol - British Hard Rubber Co., UK
Resiston - American Hard Rubber Co., USA
Rub-Erok - Richardson Co., USA
Rub-Tex - Richardson Co., USA