Unactivated D base will still lighten a tiny bit. I actually use unactivated dbase with nothing in it (or <5% white) to do tone on tone stuff sometimes. It will lighten noticeably in the dryer without any activator at all. Discharge inks are typically a bit less opaque than straight waterbased inks since they are not designed to cover the shirt color, so it will not print the same on dark shirts. I have used old discharge inks on light/white shirts without issues, but the colors do not come out identical to how they were originally mixed. Typically you will see some color shift as the pigments sit in the base for a long time, like reds become kind of orange/rusty looking. You also won't be able to control exactly how much they lighten due to the residual DC chems in the base/activator.
