Eventually Dr. Thomastik chose steel as material for the development of new strings. In the production of piano strings, there was already plenty of knowledge about steel wires which were struck by hammers. The major problem at that time was to make the steel wire usable for string instruments. Therefore, a specific processing technology was necessary. The advantages of this material lay in the resulting tuning stability, the imperviousness to climatic changes, as well as in its significantly longer lifespan. On the basis of the Austrian patent (No. 69060 – flat wire winding of Dr. Thomastik filed August 15th, 1914) and after many years of joint effort steel strings had been successfully manufactured. In 1926 strings of respectable quality were developed for all string instruments, from the violin to the contrabass.

A document dating from the year 1942 shows that at the beginning of the 1930s 50 percent of the production of strings was exported, and that Great Britain and the United States of America were the most important markets. The outbreak of the Second World War and the resulting destruction of the company through the numerous allied bombardments of the town disrupted the business. After the end of the war and the reconstruction, production was resumed in June 1946. In 1950 production levels reached those of the prewar period again.

Right from the beginning the red violin body with the curved initial „T“ was the defining logo of the company.

When Dr. Thomastik died at the end of 1951, Otto Infeld acquired the whole company. After his death in 1965 Margaretha Infeld took over the company together with her son Peter Infeld. Under the guidance of Margaretha Infeld the company not only found its present-day base in the Diehlgasse, but also became the leading supplier of strings for stringed instruments. Margaretha Infeld played an active role in the company until 1994 when her son Peter Infeld took over the sole management of the company. He led it according to family traditions up to his unexpected death in April 2009.

The time after 1950 was marked by a growth of the company. The unrivalled striving of the founders for the highest quality formed the basis for that crucial innovation which was the starting point for the success of Thomastik-Infeld. Right up to the present day this innovation has significantly contributed to the company’s success: a string with synthetic core and flat wire winding. This product – the Dominant string – is probably the most-played violin string worldwide. Itzhak Perlman and Pinchas Zukerman had already adopted this string innovation when they were unknown violin students. Later both became soloists of world rank.

Currently, Thomastik-Infeld and its almost 200 employees produce more than 2,000 various strings for stringed and plucked instruments in the very heart of Vienna, the City of Music. 97 % of the yearly produced units are exported to more than 80 countries all over the world. A strong international focus and the continuing enlargement of business relations remain an essential component of the strategy of Thomastik-Infeld.