[Boatanchors] Carbon Comp Resistors: The Darkness Gathers?

[Jacques Fortin]

Hello David,
I experienced the same thing.
It seems that it is ambient moisture absorption, combined with temperature
variations, plus the passage of time that "destroys" the CC resistors.
Even there, some brands (AB) seemingly behaves better than others or there
is just some batches more "resistant" than others ?
I have a lot of them, all values at 5% tolerance, bought new: the ones I
kept inside the house are still within their manufacturing tolerances, most
of the time, but other ones (from the same big lot I bought in 1985) that I
had stored outside in a shed for years are now reading 20% high or even
more.
I had performed some "cooking" experiments to see if the phenomenon can be
reversed, but in vain...
Carbon-film and metal-film resistors having the same "age" are still 100%
good, most probably because they are impervious to moisture.
Not sure now that thousands of NOS CC resistors (measuring way higher that
they are supposed to) interest anyone....

73, Jacques, VE2JFE