Troubleshooting: blank, faint or misaligned thermal labels

Pick the symptom: causes are listed from most to least common.

The label comes out completely blank
  1. Roll loaded the wrong way round. The heat-sensitive side must face the printhead. Do the scratch test (below): the side that turns black is the side that should touch the head.
  2. Thermal transfer labels without a ribbon. Thermal transfer labels have no heat-sensitive coating: without a ribbon nothing prints. Use direct thermal labels or fit a ribbon.
  3. Driver set to thermal transfer. In the printing preferences, choose “direct thermal” if you don’t use a ribbon.
Every other label is blank
  1. Driver label size larger than the label. The driver thinks it is printing on a longer page and runs onto the next label. Enter the exact label width and length in the driver and in the software.
  2. Sensor not calibrated. Calibrate after every roll change (often a long press on the feed button).
The print is faint or grey
  1. Darkness too low or speed too high. Lower the print speed first, then raise the darkness slightly.
  2. Dirty printhead. Clean the head with a cleaning pen or a swab with isopropyl alcohol, printer off and head cool.
  3. Old thermal paper. Thermal paper stored for a long time in heat or light loses sensitivity. Try a newer roll.
Print is shifted or cut off
  1. Gap sensor not set up. Calibrate the sensor. Check it is set to “gap” for die-cut labels, or “black mark” if the liner has marks.
  2. Margins or scaling in the software. Print at 100 % without “fit to page”. A 4×6″ PDF on 100 × 150 mm labels may need “fit” — see the 4x6 guide.
White lines run through the print
  1. Dust or adhesive on the head. Clean the head as above; label adhesive builds up over time.
  2. Dead printhead element. If the line stays in the same place after cleaning, an element of the head has failed and the head needs replacing.
Labels turn black or fade on their own
  1. Heat, sunlight, rubbing. Direct thermal paper darkens above roughly 60 °C and fades in light. For long or exposed use, choose top-coated labels or thermal transfer.
  2. Plasticisers, oils, alcohol. Some plastic films, gloves and greasy products wipe the print. Use top-coated or thermal transfer labels.

The scratch test

Scratch the label surface quickly with a fingernail. If a grey or black line appears, that is the thermal side: it must face the printhead. If nothing appears on either side, the label is meant for thermal transfer and needs a ribbon. More in how to tell direct thermal labels.

Before calling support

  1. Print the printer's configuration label (often by holding the feed button at power-on): if it prints well, the hardware works.
  2. Calibrate the sensor with the roll in place.
  3. Check the label size is identical in the driver and in the software you print from.