Horizontal lines (banding) in DTF prints: the 6 causes in order

1. Clogged nozzles

Print the nozzle check from ZoroPrint (Maintenance → Nozzle check) on a strip of film. Any gap in the pattern is a missing nozzle and prints as a light line every pass. One or two cleanings usually fix it; white nozzles need the most care.

2. Bidirectional misalignment

In bidirectional mode the head prints going left and right; if the timing is off, every other pass lands slightly shifted and you see fine alternating lines. Turn Bidirectional off in the Printer tab. If the lines disappear, set a Head gap (bidi) of 1–3 and turn it back on.

3. Too few passes

At 720 × 720 dpi the head covers each row in fewer passes, so each nozzle’s error is visible. 1440 × 720 in Medium quality is the sweet spot for DTF; High (1440 × 1440) hides banding at the cost of speed.

4. Media feed

Regular, equally spaced dark or light lines the width of a head pass mean the film advanced too much or too little. On roll feeders, check the film is not dragging; on sheets, check the rollers are clean of powder.

5. Ink starvation

Lines that get worse toward the end of a long print are ink starvation: the tanks are low, a tube has air or the dampers are old. White is affected first.

6. The file

Gradients saved as 8-bit with heavy compression band before they reach the printer. Look at the original at 200 %; if the bands are in the file, the printer is innocent.