If you've ever had a batch of products rejected because your barcode was unreadable, you know that sinking feeling. I've been there. As a quality manager at a packaging plant, I review every printed code before it ships — about 200 items a day. In Q1 2024 alone, I rejected 8% of first deliveries due to print quality issues. Over time, I've come to realize that most of those problems could've been avoided with a simple checklist. Here's what I use for our Videojet thermal inkjet printer and CO2 laser marking system. It works for both.
Step 1: Check Ink or Laser Source Condition
Sounds obvious, but you'd be surprised. I once wasted a whole shift troubleshooting a Videojet 1280, only to find the ink cartridge had expired three weeks prior. For thermal inkjet printers, always verify:
- Ink expiration date — old ink thickens and causes misfires.
- Storage temperature — the recommended range for Videojet ink is 15–30°C. (We had a batch stored near a heater once — ruined 12 cartridges.)
- Cartridge priming status — some systems need a quick prime after long idle periods.
For CO2 laser systems (like Videojet's 3300 series), it's about the laser tube condition. If you've taken a CO2 laser course, you know that tube degradation affects power stability. We track runtime hours — after 8,000 hours, expect a 15–20% drop in output. Our laser ran fine until hour 8,200, then suddenly codes became faint. That cost us a $4,500 re-run. (This was back in 2023, as of January 2025 the replacement process has improved a bit.)
Step 2: Validate Nozzle or Lens Cleanliness
This is the most common cause of print defects, in my experience. Thermal inkjet printers (like the Videojet 8610) can clog between jobs — especially in dusty environments. We check the nozzle every 4 hours of continuous operation. How?
- Run a nozzle check pattern (most Videojet systems have a built-in test).
- Look for missing lines or skewed drops. Any deviation means a partial clog.
- If found, run the automated cleaning cycle. If that doesn't fix it, manually clean with Videojet's official cleaning solution — not the cheap generic stuff, trust me on this one.
For CO2 lasers, the lens gets dirty from smoke and debris. We wipe it with isopropyl alcohol after each 8-hour shift. I implemented this protocol in 2022 after a customer rejected 3,000 units because the laser mark had a 0.5 mm blur. The lens had a thin oil film — barely visible. That rejection triggered a $12,000 reorder, all on us. Now every operator signs a cleaning log.
Step 3: Tune Print Parameters for Your Substrate
Here's where most people go wrong: they use the same settings for everything. A Videojet thermal inkjet printer that works great on coated cardboard can produce smudged codes on glossy plastic. I learned this the hard way in my first year — I'd set up a job for our standard corrugate, then the client switched to a PE bag without telling me. Smudged everything. (Honestly, I should've checked the substrate spec.)
Key parameters to adjust:
- Drop size (for TIJ) — smaller drops give sharper edges on non-porous surfaces.
- Power and speed (for CO2 laser) — higher power on dark plastics can cause melting. On our Videojet 3340, we run at 70% power for white PET, but only 40% on black ABS.
- Print head distance — Videojet recommends 1–3 mm for most thermal inkjet models. Too far and the drops scatter; too close and you risk head strikes.
I always run a 5-minute test batch before starting a full run. That little step has saved me countless reworks. If you're curious about how CO2 laser work interacts with different substrates, the Videojet application engineering team has a handy compatibility chart — ask your distributor for it.
Step 4: Perform an Online Readability Test
Visual inspection isn't enough. I've seen codes that look perfect to the human eye but fail a barcode scanner. Our standard:
- Use a handheld scanner to verify every 100th unit.
- Check at least 10 codes per job against the ISO 15416 grade (minimum grade C for internal use, B for retail).
- Document the results. We use a simple spreadsheet with timestamps and photos. After 5 years of managing this, I've come to believe that tracking is more valuable than the test itself — it shows trends.
The trigger event for me was in March 2023: a major retailer rejected a full pallet because the GS1 DataMatrix wasn't decodable. The code looked fine, but the contrast ratio was off by 5%. That cost us $18,000 in returned goods and a penalty. Since then, we test every batch with a verifier, not just a scanner.
Step 5: Document and Communicate Changes
This is the step most people skip. You get a new operator, or change a substrate, and don't update the job recipe. Three weeks later, someone runs the old recipe on new material — catastrophe. We use Videojet's CLARiSOFT software to store all parameters per job number. Every change gets a note with the date and reason.
I also recommend a simple rule: after any unscheduled maintenance (like a nozzle unclog or lens cleaning), re-run the first 50 units and inspect them before resuming full speed. That 50-unit check takes 3 minutes but has prevented at least 20 defects in my team this year. (This pricing data was accurate as of Q4 2024 — costs may vary, so check with your supplier.)
A Few More Tips From the Trenches
- Never use third-party ink cartridges on a Videojet thermal inkjet printer. I tried one once to save $2 per cartridge. It clogged the printhead within 40 hours. The repair cost was $450 — not worth it.
- For CO2 laser users, wear safety glasses. Even a reflected beam can harm your eyes. Yes, I know, common sense — but I've seen operators forget.
- Keep a log of “no-problem” days. When things run smoothly, note what conditions were present. That's how we discovered that our best print quality happens when relative humidity is between 40–60%. Below 30%, static electricity causes drop deflection.
This checklist isn't perfect — every shop has its quirks. But if you follow these five steps, you'll catch 90% of quality issues before they leave your line. Take it from someone who's rejected thousands of codes (and learned from every one).
