There's a good chance the coder printing date and lot codes on your cases is a distant relative of the printer that sat next to a beige PC in 1988. That isn't a cute analogy — it's the actual lineage. And the history of inkjet explains more about why industrial coding works the way it does — why some coders need a maintenance contract and some don't, why ink chemistry decides your substrate — than any spec sheet will.
Inkjet didn't grow from a single root. It grew two at once, for different customers, and they've been converging on the factory floor ever since.
Branch one: continuous inkjet, the stream that never stops
The old branch came first. In the early 1960s, Richard Sweet at Stanford showed that pushing ink through a vibrating nozzle breaks the stream into uniformly sized droplets — and that you can charge each droplet as it forms, then steer it with deflection plates. Drops you want go to the product; drops you don't fall into a gutter and get recirculated.
That's continuous inkjet (CIJ), and it's still how a CIJ coder works today. The stream never stops, which is the whole point: a nozzle that's always flowing can't dry out, so CIJ can use volatile solvents that flash off on contact. It sprays from an inch or more away, onto curved cans and moving bottles, at speeds nothing else touches. The names that pioneered it — Videojet, Domino — built an industry on it.
It also means a pump, a filter, a solvent loop, make-up fluid to replace what evaporates, and a service schedule. The uptime is bought with maintenance. That trade has defined the technology for sixty years.
Branch two: thermal inkjet, invented twice by accident
The second branch starts with a soldering iron. In Canon's mid-1970s lab, a hot iron touched a syringe of ink and the ink spat out; Canon filed the founding patent for what it called Bubble Jet in October 1977. Independently — genuinely independently — HP's engineers were working out the same physics: put a tiny heater in an ink chamber, pulse it, flash-boil a bubble, and the expanding bubble fires a droplet through the nozzle. Canon's Ichiro Endo and HP's John Vaught later shared a medal cited explicitly for their independent inventions.
No pump. No charge plates. No gutter. No solvent loop. Heat, bubble, drop. HP shipped first, in 1984: the ThinkJet — twelve nozzles, 96 dpi, $495 when a desktop laser cost around $3,500. Crude, cheap, and quiet.
The 1988 decision that created industrial coding
Here's the hinge of the whole story, and it had nothing to do with factories.
When HP built the DeskJet in 1988, it faced a problem every printer maker had: printheads clog, and a clogged permanent printhead is a service call. HP's answer was to stop treating the printhead as part of the machine. They built a cheap, disposable printhead into the ink cartridge itself. Change the ink, and you install a brand-new printhead. Clogging stopped being a maintenance problem and became a consumable.
That decision was made to sell desktop printers. But look at what it does on a production line. There's no printhead to service — it leaves with the empty cartridge. There's no ink system to plumb — the ink and the head are the same part. There's no make-up fluid — nothing evaporates out of a sealed cartridge. A changeover is a thirty-second swap by whoever's standing there.
Thermal inkjet didn't get engineered into a low-maintenance coder. It arrived that way, as a side effect of making home printing cheap, and the coding industry picked it up.
Why it took so long to reach plastics
If TIJ is so simple, why did CIJ own the packaging line for decades? Chemistry — and this is the honest part.
Thermal inkjet fires ink by boiling it, so the ink has to be mostly water or a volatile carrier. Feed a thermal head the aggressive ketone solvents CIJ runs on and they attack the head itself. So TIJ started where water-based ink works — corrugate, cartons, kraft — while CIJ kept the films, foils, and plastics.
That gap closed from the ink side, not the printer side. Solvent-class inks formulated to survive a thermal head are what put non-porous substrates in reach. It's why, on a modern TIJ line, the substrate question comes before the printer question — and why anyone selling you a coder should ask what you're printing on first.
Where that leaves the coder in front of you
The two branches never merged. CIJ went upmarket into big production presses; thermal inkjet went the other way — down into a cartridge, then sideways onto the factory floor — and now competes for the same date-and-lot job with none of the plumbing. Even Videojet, a CIJ leader, markets its own thermal inkjet as resolving up to four times finer than continuous inkjet.
Everything modern industrial TIJ does well traces back to that 1988 choice: the cartridge is the printhead. That's the whole idea, and it's nearly forty years old — the newest systems just make the cartridge carry more of the work.