Missing lines or gaps in the code (dropped nozzles)
Horizontal gaps or missing rows in a code almost always mean nozzles are not firing. On thermal inkjet this is usually dried ink in the nozzles after an idle period, trapped air, or a cartridge nearing empty.
- Wipe the nozzle plate gently with a lint-free wipe and run a purge/prime to clear dried ink
- Reseat the cartridge so the electrical contacts seat cleanly; inspect for ink or dust on the contacts
- Check the ink level — near-empty cartridges drop nozzles first
- If gaps persist after purging and reseating, the cartridge is likely spent — swap in a fresh one
Light, faint, or fading print
If the whole code is weak rather than missing rows, the issue is usually resolution vs. speed, contacts, or substrate — not a dead nozzle.
- Line speed outrunning the set dpi: raise the print resolution or slow the line so drops overlap
- Dirty or oxidized cartridge/printhead contacts: clean them and reseat
- Wrong ink for the substrate: water-based ink on a non-porous surface looks thin and patchy — switch to solvent
- Voltage/temperature drift in cold environments: let the system reach operating temperature
Smearing or smudging after printing
Smears mean the ink is still wet when the code reaches the next contact point, or the ink is wrong for the surface.
- Dry time vs. line speed: the code is being touched before it sets — add distance/time before the next contact, or use a faster-setting solvent ink
- Water-based ink on plastic/foil: it never fully anchors — move to a solvent ink for non-porous stock
- Downstream condensation or handling: code upstream of chillers and reduce handling of the fresh code
Blurry, fuzzy, or misaligned codes
Fuzzy edges or doubled characters usually come from the geometry between head and product rather than the ink.
- Throw distance too great: keep the printhead close to the substrate (TIJ is a near-contact method)
- Product bouncing or vibrating past the head: stabilize the guiding so the surface passes smoothly
- Encoder/speed mismatch: make sure the coder is tracking true line speed so characters are not stretched or squeezed
When to call us
Most print-quality issues come down to nozzle maintenance, matching ink to substrate, or the resolution/speed/throw geometry — and clear up quickly once you know which. If a problem persists after these checks, tell us your printer, ink, substrate, and a photo of the code, and we will help you pin it down.