I have transcribed the Donsteel section from Mosler’s official history published in 1999:
“Donsteel” frustrated burglars
“Donsteel” and “Donmetal”, named after the Mosler sales manager of that time, J.G. Donaldson, were special metal alloys that had tremendous resistance to drills and torches. The alloys were used in the construction of vault doors, lock housings, and some money safes. A famous test of Donsteel’s resistance to torches was conducted on October 14, 1924 at the Hamilton plant and witnessed by many
A typical circular “Donsteel” bank and safe deposit box door.
prominent citizens, law enforcement officials, bankers and the press. Test technicians used an oxygen lance, five tanks of oxygen and 45 feet of pipe in an attempt to penetrate a two inch thick plate of Donsteel. After the test, witnesses testified that:
“There was not even a blister on the surface thereof.”
Mosler organized the Guardian Metal Products Company in 1921 to manufacture Donsteel. A building with a 10,000 lb. traveling crane was built at the south end of Building No. 8 in which high-temperature electric furnaces were installed. However, the sale of Donsteel and Donmetal products did not meet volume expectations and the equipment was sold in 1930. The space was needed to heat-treat small money safes which were then very popular with gasoline stations and chain stores.
