Also DC will only "reform" them in one direction. You'd need to do it the other way too, which will damage the reforming.
Also they are rubbish anyway. Plastic film types are now not much larger and work far better.
I replace them with film types on sight in cross over networks.
I have a load in stock (NOS), I should really dump them
Non-polar Electrolyitcs are never meant to have DC on them ever, they will eventually pass current if there is DC, and then it will fall as it becomes a polarised type.