Epson Aculaser C1100 Series Instruction Manual page 106

Doing duplex printing manually
You can do duplex printing manually without the optional
Duplex Unit.
1. Open the Print dialog box.
2. Select Printer Settings from the drop-down list.
3. Select the Duplex (Manual) check box.
4. Click Print to start printing.
5. After printing on one side, reload the paper into the MP tray
with the printed surface face down as shown below. Then
press the N Start/Stop button.
Note:
When loading the paper, straighten it well. If curled paper is loaded,
it may not be fed correctly.
106
Using the Printer Software with Macintosh