August 18, 2006

#22 - What Kind of Aluminum is That?

I often get asked what kind of aluminum was used on vintage Airstreams. The answer is stenciled on the back of most of the original exterior skin segments on my 1956 Caravanner:

KAISER ALCLAD 2024-T3 QQ-A-362.

Kaiser is the manufacturer of the aluminum sheet. Alclad means the 2024 alloy has a thin layer of 99% pure aluminum cladding on both sides. T3 is the temper of the alloy. QQ-A-362 is some sort of federal standard specification for corrosion resistance, or something. I believe the QQ system has been replaced by ASTM numbers. Gotta look that one up!

Altough it isn't marked on the sheet, I believe all Airstream skins through the 1960s and probably even the 1970s were .032" thick.


Back of Aluminum Sheet

If you ever wondered what other metals are in 2024 aluminum alloy, (you need to spend less time thinking about Airstreams and) here's your answer as percentages of the total weight:
  • Aluminum = 90.7 - 94.7%
  • Copper = 3.8 - 4.9%
  • Magnesium = 1.2 - 1.8%
  • Manganese = 0.3 - 0.9%
  • Iron = Max 0.5%
  • Silicon = Max 0.5%
  • Zinc = Max 0.25%
  • Titanium = Max 0.15%
  • Chromium = Max 0.1%
  • All Others = Max 0.15%