If printing on an Epson printer , the interchangeable black inks allow you to choose between the printer's standard Photo Black cartridge and an optional Matte Black cartridge. The Photo Black ink supports any type of paper, the Matte Black ink supports matte paper only. The printer "knows" which ink is installed and automatically limits your choice of media types in the driver software.
The Matte Black yields higher density and contrast on matte papers and is ideal for matte fine art photography. It also produces superior B&W prints on matte paper.
On a press, according to Peter Spier on an Adobe site: "There are as many Rich Black formulae as there are printers, and you should ask yours what he recommends. Something like 70, 60.60, 100 should be printable on most presses, but you might have to cut it back a bit for some web presses. The Cyan value generally needs to be a little higher than the Magenta and Yellow to compensate for ink impurities."
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