Deoxidized Bronze
The Encyclopedia of Founding (1892)
The claims made by the Deoxidized Metal Company, Bridgeport, Conn., for their special manufacture of bronze is as follows: Deoxidized bronze is deoxidized copper alloyed with tin in any proportions desired. Thus making deoxidized bronze of any mixture stronger, tougher, denser, harder, and yet of greater elastic limit than the same mixtures of metal not deoxidized. See copy of test made by the U.S. Navy Department at Watertown Arsenal, Aug. 24, 1889, between bronze of the proportions of-- Copper. . . . . . . . . 88 Tin. . . . . . . . . . .10 Zinc. . . . . . . . . .2 made by deoxidized Metal Company of above proportions, and deoxidized; and bronzes of same proportions made at the Navy Yards at Portsmouth, N. H., Norfolk, Va., and New York, N. Y., but not deoxidized. This report shows that taking the average of the samples from the different Navy Yards, the deoxidized samples show a superiority of-- 65 8/10 per cent in tensile strength. 58 per cent in elastic limit. 18 per cent in transverse strength. 44 per cent in hardness. 60 per cent in compression. 23 per cent in elastic limit, under compression. As our price in ingot metal is less than 15 per cent greater than the same would be not deoxidized, it will be perceived that purchasers benefit themselves about 50 per cent in using deoxidized bronze, instead of making their own alloys--besides making surer casting. It is also proper to say, that deoxidized bronze of above mixtures with the zinc omitted is 15 per cent greater in tensile strength than with it, as shown by tests at Watertown Arsenal, made September 22, 1888. Deoxidized copper and bronze is superior to all copper and bronze not deoxidized. See DEOXIDIZED COPPER.
What Has Changed in the Last Century
The Deoxidized Metal Company's 1892 sales pitch rested on a real effect: dissolved oxygen forms cuprous oxide and gas porosity in cast copper alloys, and removing it gives sounder, stronger metal. What was then a proprietary product from Bridgeport is now routine foundry practice, done chiefly with phosphorus (and sometimes lithium or boron), and written into standard specifications — deoxidized high-phosphorus copper, ASTM C12200, is the ordinary material of household plumbing tube. The 88-10-2 copper-tin-zinc mixture the Navy tested survives as the gun-metal alloy C90500. Modern metallurgists would treat the advertised gains of 65 per cent in tensile strength as a comparison against unusually gassy castings rather than a general figure; deoxidizing helps, but the honest margin is smaller.
Written for this edition, 2026.