Old Cap question?

[jh45gun]

Ok I know this may sound dumb, but I am confused as I have seen it stated both ways on the web. Those old caps that have the band on one end that goes all the way around it, what does that band mean Negative or Positive? I have some in my old amp that I am working on that the schematics do not show a + just the regular = cap sign. these are the old waxy tube style cap with a value printed on them and the band on one end. I want to make darn sure what the band means before I go and replace anything. I also have some replacement caps (sprague) that have a couple of bars over each other - - only positioned vertical on the right side of the printing on the cap this mean the same thing as the band on the other caps I have.

[VaughnC]

There's no positive or negative per se in non-electrolytic coupling caps. In older coupling caps, the band was used to identify which lead was connected to the outside foil. By knowing this, you could install the cap in the circuit so that the input to the following higher impedance tube grid would be somewhat shielded by the caps outside foil layer, lessening the chances for unwanted interfering signals to get into the circuit. Typically, you'd want the outside layer (banded end) of a coupling cap facing the plate of the previous stage or the lowest impedance side of the circuit.

However, the band markings on modern coupling caps mean very little and you have to individually test them to be sure which lead is attached to the outermost layer.

[jh45gun]

So how do you test them if they are covered up which all are?