Epson 4500 - Manual (Page 75)

Printing on Special Paper
3. Reattach the printer cover as shown below.
WARNING:
Always return the lever to position 2 when you
go back to printing on ordinary paper. Continuous printing
with the lever set at a position higher than 2 can shorten the
life of the print head. Also note that printing past the edge of
envelopes, multi-part forms, labels, or thicker-than-normal
paper can damage the print head.
Multi-part Forms
With the built-in tractor unit, your printer can print on continuous
multi-part forms. You can use multi-part forms that have up to three
parts including the original. Make sure you set the paper thickness lever
to the proper position; see the table on page 2-26.
Paper Handling 2-27