Cause:
1.Label paper of low quality.
2.Low density of setting.
3.Print head is not clean.
Solution:1.Use Polono paper for best result.
2.For Windows: Go to “Settings”--’Devices”--”Printers & scanners”--”Label Printer”--”Manage”--”Printing preferences”--”Page Setup” to adjust the print speed and density.

For Mac: Open a PDF file, click on the print icon, then click on “printer preference”--”printer feature” to adjust the print speed and density.

3.Power off the printer,wait till the print head cools down.Clean the print head with alcohol using a soft towel or cotton swab.Do not use water or other liquids.