You can find instructions for using all of our different cartridge models directly on the product information page in our webstore. Just click on the product for more info and then click on the Instructions Tab. To see all of the available information on the 3880 carts (for example) click here.
Or you can download the instructions manuals from this tech site here: http://www.inkjetmall.com/tech/content.php?121-Refillable-Cartridge-instruction-manuals
From the instructions manual for the 3800/3880"
"Refill cartridges before ink level reaches 1/2” from the bottom for proper ink flow and to avoid running a cartridge empty. As long as the circle and rectangle chambers indicated above are at least 1/2 filled with ink, the cartridge does not need to be re-primed. If
the chambers are low or empty, the cartridge must be re-primed to refill the exit channel with ink. "