Technology guide
Laser Coding & Marking
Laser coding marks dates, lot codes, barcodes and logos onto packaging with a focused beam instead of ink. The beam changes the surface itself, by removing a layer, changing its color, or engraving it, so the code is permanent and there's no ink, ribbon or make-up fluid to replace. The catch is that the right laser depends on the material, and the code's contrast depends on the material too.
How it works
A laser coder steers a focused beam across the product with fast-moving mirrors, forming characters and codes as the pack moves past. Where the beam lands, it removes a thin top layer (ablation), changes the material's color, or engraves it.
Because the laser marks the material itself, two things decide the result: whether the material absorbs that laser's wavelength, and whether the mark shows up against the surface around it. That's why there are different laser types, and why some packaging is designed with a laser window (see below).
CO2, fiber and UV: which laser for which material
The laser has to be absorbed by the material to mark it, and each type works at a different wavelength. Match the type to what you're marking.
How it marks: Heat: burns or removes the surface layer
Marks well: Paper, cartons and corrugate, glass (a frosted mark), wood, many plastics including PET, coated films
Struggles with: Metals (the beam isn't absorbed); some plastics give a low-contrast mark
How it marks: Penetrates and reacts with the material
Marks well: Metals (steel, aluminum), engineered and high-density plastics
Struggles with: Transparent materials (the beam passes through); low visibility on cartons
How it marks: "Cold" marking with little heat
Marks well: Heat-sensitive plastics, flexible films and pouches, fine high-resolution marks
Struggles with: Less common on general packaging lines; check fit for your material with the supplier
| Type | How it marks | Marks well | Struggles with |
|---|---|---|---|
| CO2 (infrared, ~10.6 µm) | Heat: burns or removes the surface layer | Paper, cartons and corrugate, glass (a frosted mark), wood, many plastics including PET, coated films | Metals (the beam isn't absorbed); some plastics give a low-contrast mark |
| Fiber (infrared, ~1,060–1,090 nm) | Penetrates and reacts with the material | Metals (steel, aluminum), engineered and high-density plastics | Transparent materials (the beam passes through); low visibility on cartons |
| UV (355 nm) | "Cold" marking with little heat | Heat-sensitive plastics, flexible films and pouches, fine high-resolution marks | Less common on general packaging lines; check fit for your material with the supplier |
Laser on cartons: the flood-coat window
On printed cartons and labels, a laser often marks by burning off a top layer of ink. So for a readable code, the packaging is usually designed with a dark printed window (a "flood coat") where the code goes. The laser removes the dark ink and exposes the lighter material underneath, making a light-on-dark code. A white layer under the flood coat improves contrast for barcodes.
What it means for you: laser coding on cartons often starts with your packaging artwork, not just the coder. Plan the window with your printer or converter before you commit.
Safety and fume extraction
Coding lasers are powerful enough to cause permanent eye damage, so they run inside guarding or a rated enclosure with interlocks, under your plant's laser-safety program. Marking also creates fumes and particles from the material it removes, so laser coders need fume extraction with filters. Those filters are the main recurring item: the laser has no ink to buy, but the extractor's filters need changing.
Speed and the moving line
Lasers mark on the fly as product moves, which suits high-speed lines. How fast depends on how much the laser has to mark: more characters, larger codes or deeper marks take more time per pack. Size the laser to your code and your line speed together.
Best for
- Permanent, tamper-evident date and lot codes
- High-speed lines where you don't want ink or ribbon changes
- Anti-counterfeit and traceability marking
- Metals (fiber), glass and cartons (CO2), and heat-sensitive films (UV), with the type matched to the material
Considerations
- Typically a higher up-front cost than ink-based coders
- The laser type must match the material; one laser rarely suits everything on a mixed line
- Printed cartons often need a flood-coat window designed into the artwork
- Guarding or a rated enclosure, a laser-safety program and fume extraction with replaceable filters
- Contrast depends on the material: the code is the material, changed
How it compares to thermal inkjet
Laser marks the material itself: permanent, with no ink to buy, but the laser type has to match the material and printed cartons often need a flood-coat window. Thermal inkjet (TIJ) prints dark ink onto the surface, so the code shows on almost any pack without changing your artwork. You match the ink to the material instead (water-based for cartons and paper, solvent for plastic, film, foil, metal and glass), with resolution up to 600 dpi and little scheduled maintenance. Many plants run thermal inkjet for everyday date and lot coding and keep laser for permanence or anti-counterfeit work. We supply thermal inkjet, and we're happy to help you weigh the two for your line.
TIJ Print Solutions specializes in thermal inkjet. We’re happy to help you choose the right technology for your line — even when that conversation starts here. Explore our coding & marking inks.
Not sure which technology fits your line?
Weighing laser against thermal inkjet? Tell us about your line and a TPS coding specialist will help you compare.
Frequently asked questions
What is laser coding?
Laser coding marks dates, lot codes, barcodes and logos onto products and packaging with a focused beam instead of ink. The beam removes, changes the color of, or engraves the surface, so the code is permanent.
What are the advantages of laser coding?
Permanent, tamper-evident marks; no ink, ribbon or make-up fluid; and marking on the fly at high line speeds. It's well suited to anti-counterfeit and traceability work.
What's the difference between CO2, fiber and UV lasers?
They work at different wavelengths, so they suit different materials. CO2 marks paper, cartons, glass and many plastics but not metals. Fiber marks metals and engineered plastics but not transparent materials. UV marks heat-sensitive plastics and films with little heat.
Can a laser mark cardboard cartons?
Yes, usually with a CO2 laser. On printed cartons, the code is often marked into a dark flood-coat window printed on the carton, so the lighter material shows through as the code.
Do laser coders need consumables?
No ink, ribbon or make-up fluid. They do need fume extraction, and the extractor's filters are a recurring replacement. Plan for guarding and a laser-safety program too.
Laser coding vs. thermal inkjet: which should I choose?
Choose laser for permanent, consumable-free marks or anti-counterfeit needs, with the laser type matched to your material. Choose thermal inkjet (TIJ) for a lower up-front cost, a dark code on almost any pack without artwork changes, and high-resolution codes from a cartridge swap. Many lines use both.
Does TPS sell laser coders?
No. We supply thermal inkjet printers and Odyssey inks. We're glad to talk through whether laser or thermal inkjet fits your line better.