If all you're doing is black(mono) text output and no color see if *possible* to set printer to black output only(mono). Also, verify you may want simpler text, use the draft mode for degraded text output. It really doesn't matter for text as it comes out fine, but I don't know if your printer is capable of such. Check all that under it setting menu. Also, some ink carts have available fuller capacity carts, so if the #21 is such( I don't remember), I believe like 20ml vs 40ml.
I would like to enquire if anyone experience this.
I bought a new HP 21 ink catridge as my current one has run out. After less than 1 week, it ran out of ink (some parts of the printed page are clear some are not, as if it is running out of ink). I thought I may have printed alot in that week as I have quite a few assignment papers that i needed to print. So I got a another new one. This time, after printing around 50 or so pages the same thing happened!
I checked HP site, it mentioned at least 190 standard pages for each HP21 ink catridge. I'm using HP Deskjet 3940. Can someone tell me what is happening? Not cheap if this goes on.