The latest PostScript Printer Descriptions (PPD’s) are missing after installing Mountain Lion OS (MAC). This can lead to certain printing issues and duplex printing with several printers such as HP, Lexmark and EPSON.
Apple has changed the way the PPD’s were available before. Now Apple delivers 3rd party software for printers and scanners via software update. Please find a comprehensive list of supported printers and scanners by visiting the URL below
In case of using Printer Drivers [E.g. HP 5500 dn] which are not supported by Mountain Lion it will result in incorrect output or some features unavailable or not working e.g. Duplex Printing.
Note: The same printer drivers are compatible with Snow Leopard and Lion OS, but they might not work on Mountain Lion.