Re: [VAL] Gauge or thickness of 1972 airstream globetrotter aluminum skin

["Tom" <thomm@xxxxxxxxxxxxxxx>]

"Age hardening product" ?

I know the designation 'T-6' tells you how the aluminum alloy was "hardened" 
and then you know what that process was such as so much time at one 
temperature, then boosted to a higher temperature for a set amount of time, 
quenched in whatever, etc.

But I've never heard or understood aluminum alloy that has been heat treated 
using it's number designation as an "age hardening product."

In the aircraft business we didn't have dates to  use aluminum alloy by - 
like in the grocery stores where they have the 'sell by date' for foods.

I've used all types of aluminum alloys in the construction and repair of 
aircraft and never once have I found or been informed that the metal was - 
"too old to use."  This is what your statement seems to imply when you say 
that metal "gets harder as it ages".  Well, it did get harder (T-6) when it 
was heat treated, but then that treatment was stopped after a certain amount 
of time depending on what you wanted or needed the metal to be for whatever 
use it was going to be in an aircraft.

Metal that's too old to use?  I've never heard that one before.

Tom
WBCCI 5303