1.Try to choose PDF file format for printing instead of PNG, PIG, and other image formats, when the barcode you print out is light (please refer to the picture)
2.If the font is still not clear, please try to increase the density and reduce the speed. (Please refer How to adjust the density and speed in the settings?)
3.If it is still not clear for the label, you can wipe the print head with alcohol wipes or wet tissues.
Here is the video to maintain the print head:https://www.youtube.com/watch?v=pE6Ps-AFjEQ