Glucydur is a trademarked name for an alloy of beryllium and bronze typically used in balance wheels. The development of Glucydur in the 1930s coincided with that of Nivarox for balance springs and caused a revolution in construction and accuracy of an assortiment.
The Search for Stable Balance Materials
The development of advanced materials for watch balances was necessary due to many undesirable aspects of steel, which had been the primary material until the 20th century. The main issues were corrosion, magnetism, and temperature-related changes in size and shape or to the modulus of elasticity. Many novel solutions had been developed, including careful tuning of the various components, bi-metallic components, and temperature-compensating designs. The primary method at the end of the 19th century was to use a bi-metallic cut balance, which contracted as temperature rose, to compensate for the reduction in elasticity of a steel balance spring.
The "perfect" meter sample produced by the International Bureau of Weights and Measures in Paris used an alloy of 90% platinum and 10% iridium. 30 such examples were produced in London, but these were far too expensive and rare to be of practical use. Swiss physicist Charles-Édouard Guillaume was assigned to investigate other alloys, specifically nickel-steels alloys, which were first produced in 1888. These were found to exhibit strange magnetic properties at different temperatures by English scientist Dr. John Hopkinson, and Bureau Director, Dr. Benoit, was curious if they had other properties.
The investigation lead Dr. Guillaume to develop Invar, an alloy of 36.1% nickel was almost entirely stable. Although many attempts were made to produce Invar balance springs, the material proved to be more interesting in other applications. Paul Perret of La Chaux-de-Fonds noted that an Invar balance paired with an ordinary steel spring dramatically improved the stability of a chronometer and produced a test device to show Dr. Guillaume in 1897. Perret formed a company and built a factory in Fleurier to mass produce Invar balances and springs but faced hardships raising money and beginning production. He died in 1904, with his company taken over Fabriques de Spiraux Réunies, which intended to focus on Invar balance springs.
Thus, through the 1930s, most watches used complicated laminated bi-metallic balances with an array of screws for hand poising.
Nivarox and Glucydur
Reinhard Straumann, technical director of Thommens Uhrenfabrik, developed an improved balance spring material in his own Waldenburg lab in 1931. He collaborated with the German materials firm Heraeus in Hanau to produce the new material in a vacuum smelter, and the resulting alloy of nickel, iron, and other metals exhibited stability of elasticity despite changes in ambient temperature. He named the material Nivarox ("ni variables, ni oxydables"), since it it was resistant to fracture, corrosion, and magnetism. Nivarox was perfected in 1933 and patented in 1935.
Straumann initially produced Nivarox with the Karl Haas company of Schramberg, Germany, but the Swiss industry was worried that this gave the Germans too much control over Swiss industry. At the urging of ASUAG, Straumann left Thommen in 1934 to establish domestic production of Nivarox in a joint venture in Saint-Imier with Albert Ruch of W. Ruch & Cie, maker of Berna brand springs. Albert Ruch died just a year later, so Straumann's department was split off and re-formed as Nivarox SA in 1937 under the control of ASUAG.
At this same time, another alloy was gaining attention. Made of beryllium, copper, and iron, it was incredibly stable, non-magnetic, and non-corrosive. The watch industry realized that a balance made of this new material could be paired with a Nivarox balance spring to create a much-advanced watch balance. The Fabriques de Balanciers Réunies branch in Bienne began using the name Glucydur to market this material for watches by 1935 and trademarked that name in 1937.
A Glucydur balance was so stable that it could be poised in the factory and would remain so for the life of a watch. It was also an attractive material, with a brilliant golden finish and smooth luster. Although some watchmakers preferred to have balance screws for hand poising, they were mostly unnecessary in Glucydur balances, leading to the adoption of smooth, uncut balance wheels in the 1940s.
Soon, Glucydur balances and Nivarox springs dominated the watch market and reduced the need for careful hand adjusting and compensation.
A Société Anonyme corporation was set up in the name of Glucydur SA in 1938. It was a joint venture between FBR (which controlled 70% of the stock) and Ebauches SA. The company was directed by Werner-Alfred Vaucher (president), Samuel Emery (secretary), Rodolphe Stadler, Heinrich Thurnheer, French national Robert Nadeau, and Ebauches SA chairman Sydney de Coulon. The company was located at Fig. de l'Hôpital 8a in Neuchâtel, which also housed Ebauches SA. Vaucher was quickly replaced as president by Robert-Henri Guye, who died in 1942 and was replaced by Samuel Emery, while Maurice Favre and Alphonse Bernhard (secretary) joined the board.