HP Color LaserJet 8550 Multifunction Printer series - Manual (Page 105)

EN
Selecting original type 105
If you select the following two modes simultaneously, the copy module
will make copies of originals in the Black Text setting, even if the
Text/Photo/Map setting is selected:
! Black Monochrome mode (the B LACK key lights). For information
on switching between the Full Color mode and the Black
Monochrome mode (including ACS), see page 125.
! When Text Priority is selected in Text/Photo Priority Black
Monochrome mode, see “Text/Photo Priority in Black mode” on
page 238 for more information.