Reason 1: The source file wasn't created in the ideal quality:
Solution: Print the sample label to test if your printer is working well.
You can download the sample label from thecomplimentary USB drive :
http://doc.omezizy.com/Labels-Sample.pdf
Reason 2: High print speed or density.
Solution: Try reducing your print speed (try 3 in/sec) and density (try 3 as well) to see if you get a better result.
For Mac
①Select "Printer Features" in "Preview"
②You can change the printing speed and the Darkness of your printing
(Larger number means higher Darkness)
For Win
Go to "Control panel" -> "Devices and Printers"
(Right click on "This PC", choose "Properties", then click on "Control panel"-> "Devices and Printers")
-> Right click on "Label Printer" -> choose "Printer Preferences" -> go to the "Option"
-> You can change the printing speed and the Darkness of your printing
(Larger number means higher Darkness)
