TO PRINT “STRAIGHT-THROUGH” ON THE HP OFFICEJET PRO 8500:
Note: If you are printing labels on, for example, Avery mailing label sheets, or printing thick brochures or certificates, you can open the slot on the back of the Officejet to allow the label sheet or thicker paper to feed straight through the printer. This prevents the label sheet or thicker paper from curling and reduces the likelihood of a paper jam.
1) Gently turn the Officejet around so you don't accidentally unplug any of the cords going into the back of the Officejet.
2) Locate the two small buttons near the center of the slot cover on the back of the Officejet. (The slot cover is on the “Duplexer” attachment that allows you to print on both sides of the paper.)
3) Pinch the two small buttons together and flip the slot cover down.
4) Print the labels or the sheet of thicker paper.
5) Remember to flip the slot cover back up again when you are done.