In the early part of the 20th Century, an organisation called “The Artificial Horn Manufacturers Association” was established. I wonder if this caused consternation in the Worshipful Company of Horners, the guild historically charged with protecting the craft of the authentic workers in horn? Fortunately, it soon became apparent that this organisation was the Trade Association formed by the UK manufacturers of Casein Plastics, and therefore only an indirect threat!
There is, however, a strong link between casein plastic and horn, since both are materials based on natural proteins derived from cattle. Horn from keratin and casein plastic from casein, the principal protein of cow’s milk. In fact, the word casein is derived from the Latin word for cheese, caseus. Today, casein plastic would be termed a biopolymer, i.e. a polymeric material derived from a natural replenishable resource. It is a tough, non-flammable, polymeric material with good impact strength, but poor dimensional stability and poor moisture resistance. It will be familiar to many PHS collectors in the form buttons, beads and bangles.
In the manufacture of casein plastic (“wet-process”), the protein is precipitated from cow’s skimmed milk by addition of rennin, a natural enzyme from rennet (membrane of the cow’s stomach), which is capable of clotting 400,000 times its weight of casein. It is then processed into rods or sheets, which are soaked in formalin (a 4% aqueous solution of formaldehyde) for hardening. This stage is the most important, and most expensive, part of the entire process. The thickness of the mass governs the length of time required, which in any case is never less than one week, and may be as long as a year for sections of ca. 25 mm thickness. After hardening, the material is dried to moisture content of 8-12%, an operation that is likewise slow. The hardening process can be ascribed to condensation between the aldehyde and the amino groups of two adjacent casein molecules:
RNH2 + HCHO + H2NR >>>>>>>> RNHCH2NHR + H20
Extrusion rates for rods were only a few Ibs. per hour. Pigments were added before processing (both twin and triple barrel extruders being used even then for multi-colours), or dyes could be used later for surface treatment. As a result of distortion occurring during formalin treatment, the products were machined/polished into the finished articles. The ultimately preferred manufacturing process, known as the “dry process” started with dried rennin casein granules.
The initial patent on casein plastic was awarded to a Bavarian chemist, Adolph Spittler in 1899, that is before Bakelite (1907)! The story behind the invention was that his cat jumped onto his work-bench and spilt formalin into its saucer of milk, and overnight a white solid was formed in the saucer! After a very short development phase, the product was introduced at the Paris Universal Exhibition in 1900.
Spittler licensed his invention to firms in Germany and France, that eventually merged in 1904 to form the International Galalith Gesellschaft Hoff and Company, with Galalith, which translated means “milk stone”, as the trade name. As is usual in scientific discovery, around the same time, a “wet process” based on milk curds was patented by a Latvian chemist, Victor Schutze, and introduced into the UK as Syrolit, and a factory of the same name was set up in a disused cloth mill at Stroud in Gloucestershire. The “wet process” employed was expensive and unreliable, and the company went bankrupt in 1913. A new company was, however, established at the same premises using the “dry process”, and the product was called “Erinoid”, which was also adopted as the name of the company. When the supplies of Galalith to the UK were cut off with the advent of WW1, Erinoid found a ready market (even at a production output of 5 tons per week).
Other UK manufacturers of casein plastic were established post-war, and included BX Plastics (1922) with Lacroid; Young & Wolf (1930); and Charles Horner Ltd of Halifax with Dorcasine. These companies, together with Erinoid were the founders of “The Artificial Horn Manufacturers Association”, who eventually became the Casein Plastics Association in 1938. (Under pressure from the Worshipful company of Horners?).
Erinoid had what was to become a particular association with the Horners’ Company. During WW2, Leicester Lovell (Adhesives) of Gloucester was evacuated there, and Hac Collinson was in charge of that operation. Erinoid became a public company, where a then young Past Master Eric Hunt and David Crabtree were employed, and was subsequently acquired by O & M Kleeman, associated with Past Master Harry Kleeman’s family.
In my own case, I remember visiting the casein plastic manufacturing unit at Stroud as a young chemist in the late 1960s, after the whole Erinoid operation was bought by BP from Mobil Chemicals, who had acquired it from Kleeman in 1961 (for $20million). It would be hard to forget my first visit, as the dated building, stocked with ancient equipment, reeked of formaldehyde, but hearsay was that no-one who worked there caught a cold!
Not surprisingly, BP Chemicals shut down the casein operation soon afterwards. This was the end of manufacture in UK, but the “most beautiful of plastics” as casein was once known, is still manufactured in countries with a strong dairy economy, such as New Zealand. The beautiful buttons and artefacts are also still available for purchase from companies such as the Italian manufacturer, Ontano (www.ontano.com).
Colin Richards — January 2008
With acknowledgement of historical input, and helpful comments, from Eric Hunt, Past Master of The Worshipful Company of Horners.
