I've had good luck with a
variable HV DC supply. I bring up the voltage, albeit slowly, while
monitoring current with a microamp meter. It's nice to watch the
current gradually go lower, then I step up about another 50 volts or
so then watch it go lower again until I reach the rated voltage of the
cap. I let it "Cook" there for awhile then use the cap.

Tony & Mark-

I consider ten-year-old electrolytics to still be "new", and of a newer
generation than those that established a reputation for going bad when first
powered-up after being in storage. Its those thirty and forty-year-old
capacitors I worry about!

I have an old Eico capacitor checker with the "electric eye" indicator for
leakage. The voltage is also somewhat current limited. Years ago when I was
working with it, I would connect an old electrolytic to it and raise the
voltage until the eye just closed. Depending on capacitance and leakage, the
eye would slowly open. I would then continue raising voltage and waiting for
the eye to open, until the rated voltage was reached, typically 450 volts.

This is equivalent to forming a capacitor by using the variac or series light
bulb. I never worried about cooking it, since there was obviously no leakage
soon after full voltage was reached. I think you will find those that still
have leakage after several minutes, are beyond help. (Obviously ten mfd will
charge a thousand times more quickly than 10,000 mfd.)

I think I'll go reform the capacitors in my capacitor checker!

73, Fred, K4DII