The biggest difference is not in shade of black but chemistry of ink itself. I won't bore you with PH levels, polymers, stabilizers, yada, yada, yada. With fantastic resolution of inkjet printers these days nozzle holes in print heads are getting smaller and smaller. If ink can't get through tiny nozzle hole result is, yep, you guessed it... a clogged print head.

Black inks are specialized because you want largest particle size for blackest black, however, you don't want it to be too big as to risk clogging print head. Most printers have different diameter nozzle holes which is why there are so many specific kinds of black ink.

Some black inks can be used in different printers that use same basic technology like HP and Lexmark. Many of our black inks for these printers are actually same exact thing poured from same bottles.

What's a person to do? You ask, "Can my new cartridge be refilled while I'm waiting for after market to catch up?". Thankfully answer is a resounding YES! If manufacturer got ink inside that bugger you can bet you can too. "What about inks?", you ask.

Many new cartridges are just re-hashes of old ones with minor variations. While you're waiting you can experiment with your old cartridges and try to refill them with ink you already have. There are some guidelines to follow here though because I don't condone a one ink fits all solution.