Would they be more stable if you contained them in a cloud of goop?
P.S. I think the idea of baking out the caps is brilliant. It would be interesting to bake out an entire amp if one could adequately characterize it before/after. I'm thinking vintage amps here - amps that have spent their lives in the humid south.
David Root wrote:Good question.
Stored in Mason jars over desiccant, indefinitely.
In service, I guess I'll find out, but the interior of a chassis generally runs pretty warm, so I would expect pretty much the same as a new 2013 cap.
Remember it took a good 40 years or so for these epoxy caps to absorb enough moisture to drive up their capacitance 20 to 40%. Their original environment was Houston, which is pretty extreme humidity situation most of the year.
Thanx vibratoking, the ceramic info was new to me. I don't think you derailed anything, my work was solely with epoxy dipped paper/mylar/Al foil caps.
I did this work in conjunction with Mark Huffman of markoparts.com. He believes that in these caps the moisture simply enters the cap thru the joint between the leads and the epoxy encapsulation and is just physically adsorbed into the dielectric.
Simply raising the interior of the cap to a temperature high enough to raise the vapor pressure of the adsorbed water enough to force it back out of the cap would be the mechanism.
As Mr. Spock would say, this seems logical.
We decided to limit the treatment temperature so as not to exceed the maximum operating temperature spec of the caps which was 250 deg F.
Zippy, I wouldn't bake an entire amp but I suppose you could do it. Of course all the ceramic caps would be de-aged back to their original values!!
