Aluminum radiator field brazing development

Pre-1980, automotive radiators were Cu, field-repairable by mechanics with propane torches. All-Al radiators (e.g., Corvette) required factory brazing only. Around 1980, Alcan Aluminum developed a fluoride-based field-brazable flux for Al. Result: industry-wide transition Cu → Al for radiators.

Automobile radiators. Back when I was your age, most radiators were copper in cars. A mechanic could repair a copper radiator — if it sprung a leak, he'd get out his little propane torch, pour braze alloy in until it held air pressure, and loaded up until another leak started. Around 1980, Alcan Aluminum developed a brazing flux for aluminum that was not so fussy that you had to do it in a plant. The mechanic in the auto shop could take some of this flux, paint it on with a little acid brush, and braze it just like he was brazing copper. This was a fluoride-based flux — don't tell him he's strengthening his teeth by breathing this in. Hydrofluoric acid and others. They developed a brazing technique so that radiators didn't have to go back to the factory. In the early 1970s, the only automobiles with all-aluminum radiators were things like the Chevy Corvette, where weight was critical. If you could afford to buy a Corvette and you sprung a radiator leak, you just bought a whole new radiator. You could braze them in the factory in the early 70s, but you couldn't field-braze them until Alcan developed this brazing flux. With that brazing flux, they opened up a whole new industry, got rid of all that copper, and now aluminum is used for brazed radiators.