Updated 13-II-2019

Edward G. Zubler

This article is based on a document of fellow lamp engineer and collector Edward J. Covington, which appeared on his website of biographical sketches of persons involved in the lamp industry. Following his passing in February 2017 and with kind permission of his family, Ed's words have been preserved and subsequently expanded with new material by this author, to maintain continued access to the research he initiated.

Edward George Zubler1

Edward George Zubler was born on March 12, 1925 in Lackawanna, New York. At age 18, in 1943, he entered the U.S. Army and served in the 102nd Infantry Division in the Rhineland Campaigns. During a military service career that lasted from 1943 to 1946 he attained the rank of Staff Sergeant and was awarded a Bronze Star and Purple Heart, both with the Oak Leaf Cluster. He earned a Bachelor of Science degree in Chemistry from Canisius College in Buffalo, New York in 1949. He then earned a Ph.D. in Physical Chemistry from the University of Notre Dame in Notre Dame, Indiana in 1953.1

Ed Zubler's work experience with the General Electric Company began in 1953. His career extended over a period of 34 years, working in the Lighting Research Laboratory. Ed held the positions of Research Physical Chemist, Technical Leader - Halogen Lamp Chemistry, and Research Advisor-Physical Chemistry. During this period he was fondly respected as an untiring mentor to the younger members of staff. His is most recognised for his joint invention of the tungsten-halogen lamp, which is described in detail in the section below.

Because Zubler was so knowledgeable in the area of lamp chemistry, he was a much sought-after speaker. Besides giving invited lectures in the Cleveland area, such as at Cleveland State University, Case Western Reserve University, John Carroll University and the University of Toledo, he also delivered presentations at the Gordon Conference on High Temperature Chemistry, Eötvös University in Budapest, Hungary, Rensselaer Polytechnic Institute in Troy, New York, Kernsforschungsanglage-Jülich in Germany, SRI International in Menlo Park, California and at the Sandia National Laboratory in Livermore, California. He was a frequent visitor to Europe during intercompany lamp-technical exchanges between GE and Osram in Germany, Tungsram in Hungary, and Philips' Central Development Laboratories in the Netherlands. He also organised two symposia on High Temperature Lamp Chemistry for the Electrochemical Society in 1985 and 1988.

Ed was honored by his employer General Electric with the Steinmetz Award, and by Toshiba by being included among the technical pioneers in the Toshiba Science Institute. He received the Willem Elenbaas Award from N.V. Philips Gloeilampenfabrieken in 1981 for 'studies leading to a better understanding of the phenomena ocurring in halogen lamps and for the innovations that resulted from these studies'. Additionally he was granted several patents for lamp design and process innovations in incandescent, halogen and metal halide lamps.

Ed Zubler married Marybelle Browning in 1950 and they had children Karen, Kurt and Rena. He retired in 1988, and passed away on March 20th 2004. The photograph above was taken in the 1960s.

Development of the Tungsten Halogen Lamp
Ed Zubler is perhaps most famously remembered for his pioneering role in the development of the first practical tungsten-halogen lamps. He initiated a series of experiments to try to understand why the early prototypes were giving short life, as reported on the page of their co-inventor Elmer Fridrich. The reason was found to be due to the water that was being introduced with the iodine crystals. After that discovery Zubler became a member of the halogen development team.

Zubler then began in-lamp experiments in an effort to obtain cleaner lamps. However, the net result of those efforts was just the opposite of what was desired - he produced blacker lamps. The efforts were carried out over a period of about three years with little success. At that point it was decided that if efforts to make a clean lamp were not successful, a different approach needed to be taken. The approach Zubler took was to try to make dirty lamps —and from these experiments the secrets of successful lamp making hopefully might be uncovered. At that point he began to add small quantities of oxygen to the lamps. Eureka! — Clean lamps resulted, and with somewhat longer lives! However, now a new problem arose. In many cases arcing occurred, which ended lamp life prematurely. Zubler then increased the cold fill gas pressure of argon, which suppressed the arcing, and the major problems ceased to exist.

Thus, after determining that a small quantity of oxygen, as well as a higher fill pressure of argon were required, the regenerative cycle taking place within the tungsten-iodine lamp was beginning to be understood. It was found that a tungsten oxyiodide compound probably was involved in the working of the cycle. This fact could be surmised from Zubler and Mosby's patent3, where the final filling consisted of about 600 to 1500 Torr of pure argon, about 0.3-0.5 Torr of oxygen and about 5 Torr of iodine. This step is considered by many to be the enabling technology to achieve high efficacy, long life halogen lamps. However, it was necessary that work be continued in order to understand the effects of envelope impurities and well as those impurities that were inadvertently added during processing. Attention also had to be given to the support wires, for example, for any role they might be playing. Zubler's studies eventually helped to establish both design and processing specifications.

A visual demonstration of the cleanup of a blackened lamp envelope is shown below. Zubler sealed lamps to his vacuum system and subjected them to a hydrogen cleanup procedure. Silicon oxides were removed by torching and the lamps were then blackened under high vacuum conditions to deposit tungsten on the lamp wall. Next, measured amounts of iodine and oxygen were added. The lamps were then sealed off. Upon operation the lamp walls would clean up in less than one minute.

An artificially blackened halogen lamp (above) and cleaned up (below) after running in halogen for about 1 minute

An early 500-watt, 120-volt quartz iodine lamp

  1. "Iodine Incandescent Lamps", U.S. 3,132,278, May 5 1964 (with C.B. Collins)
  2. "Method of Manufacture Of Iodine Cycle Lamps", U.S. 3,160,454, Dec 8 1964 (with F.A. Mosby)
  3. "Iodine Cycle Incandescent Lamps", U.S. 3,240,975, Mar 15 1966 (with J.F. English)
  4. "Getter Composition for Electric Lamps and Similar Devices", U.S. 3,508,856, May 25 1971
  5. "Getter Processes for Electric Lamps and Similar Devices", U.S. 3,679,285, Jul 25 1972
  6. "Mercury Pressurized Incandescent Lamps", Canadian 1,280,149, Feb 12 1991 (with E.J. Covington)

References & Bibliography
  1. Communications from Ed Zubler to the writer.
  2. "Edward G. Zubler (1925-2004)", Obituary, in Proceedings of the 10th International Symposium on the Science and Technology of Light Sources, Toulouse, 18-22 July 2004, C.N.Stewart & R.S.Bergmann, p.IX.
  3. "Method of Manufacture of Iodine Cycle Incandescent Lamps", Edward G. Zubler & Fred A. Mosby, U.S. Patent 3,160,454, Dec 8 1964.