Mike,
>Can you elaborate on the time frame it takes for the ink dispersant to oxidize?
I rely on the expiration dates on the inks. I suspect they set those dates largely on whatever the rate of oxidation is, and that will vary with the particular dispersant technology. On the other hand, those dates are conservative. The companies know that the inks can be in the cart and printer for a long time after the retail sale.
Early in this inkjet era I noticed that partially used old original Eboni pint bottles collapsed in notably. I wondered what this was, since the carbon was supposed to be so "archival." Now I assume that was the oxygen being pulled out of the air in the bottle by the dispersant oxidation, not that of the pigment particle.
Frankly, I don't worry about the issue that much, but if I'm way over the expiration date, I don't use the ink.
Paul