I not infrequently add a bit of water and reconstitute ink in old cartridges. I have been told it is possible to reseal these cartridges so they do not have to be used immediately. For the life of me, I can't imagine a way to do that. Any experience out there? Every idea I can think of would risk clogging the nipple.
I've even been told that some people fill (clean) old cartidges with new bottled ink as a way to carry ink while traveling. Makes some sense if you can reseal the cartridges.