Pigment or Dye Ink in a TIJ Cartridge: What Actually Survives

Two inks can print the same colour on the day you buy them and look completely different after a year on a pallet in the sun.

The reason is not the hue. It is the form of the colourant: a pigment is a dispersion of solid particles held in a carrier; a dye is dissolved in it. A dissolved colourant travels as individual molecules. A dispersed one travels as particles that must be kept from clumping — which is why pigment inks carry dispersants, and why particle size distribution is part of their specification.

That single structural difference explains most of what a buyer notices later: which ink fades, which survives a solvent wipe, what happens to the nozzle when a cartridge stops, and why white is almost always a pigment.

Why the distinction is not academic

What it changes about colour, and about white

White is the clearest case, and it is the one most coding lines meet. A white dye that stays white does not exist in any practical industrial ink. To look white on a dark compound the ink has to scatter light, and scattering needs particles — which is why the white and yellow marks on a black cable jacket are pigment inks, and why they read as an opaque layer rather than a tint. The cable and pipe coding page shows what that looks like on a real jacket.

On a dark surface the ink has to carry the contrast itself, and that has a consequence for the print specification: coverage matters more than resolution. A 12.7 mm print width holding three lines of small text and a 25.4 mm band holding the same content are not interchangeable at the same line speed, because the amount of ink laid down per unit area is what the eye reads as contrast.

Colour range follows the same logic. Our cartridges are supplied in black, cyan, magenta, yellow, white and red, and the white is the one that exists because of pigment chemistry rather than in spite of it.

Light, heat and time

This is where the two diverge in a way that shows up months later, on stock that sat near a window or on a pallet outdoors. Dyes are, in general, more prone to fading under ultraviolet light, because the colourant molecule itself can be broken by photon energy. Pigments resist that better, because the particle is a solid and the colour survives even when the binder around it degrades.

The distinction matters for how a complaint is diagnosed. A mark that has faded rather than flaked is a pigment-and-binder question, not an adhesion question: the ink is still where it was put, it simply no longer has the contrast it had. The diagnostic order for adhesion failures covers the other case, where the mark is physically gone.

Heat is the second half of it. A retort cycle, a pasteurisation tunnel or a hot-fill line puts the code through temperatures the binder has to survive, and a pigment dispersion can be more sensitive to the carrier flashing off too quickly than a dye solution is. Neither is automatically better; the failure modes are simply different.

What it changes on the line

Three practical consequences, in the order a line usually meets them.

Drying budget. A pigment particle is larger than a dissolved molecule, so the same colour can need a different formulation to dry inside your budget. On non-porous surfaces our fast-dry solvent inks are typically dry to the touch in 1–5 s. That is a range published for the ink class rather than a promise for your line, and the only way to close it is to print on your material at your speed.

Maintenance after a stop. A dispersion that loses its carrier can settle, and a nozzle that has dried out is not recovered by printing. On a TIJ cartridge the nozzle plate, reservoir and filter are one assembly, replaced together — which is why a long stop costs a cartridge rather than a cleaning cycle.

Substrate matching. Surface energy still decides whether the ink wets at all. The working rule is that the substrate needs to sit roughly 8–10 mN/m above the ink’s dynamic surface tension, and polyolefins such as PE and PP commonly need to be above about 38 mN/m, which is why they usually need corona or flame treatment first. No colourant choice gets around that. The substrate matching guide works through the materials one by one.

None of this is a catalogue decision on our side: we formulate and fill our own inks, so colourant and carrier can be discussed together against your substrate rather than against whatever happens to be stocked. What we make and what we buy in — printheads are qualified, not manufactured — is set out on the manufacturer page.

Where each one is the right answer

• Pigment where the mark has to be opaque, especially a light ink on a dark substrate: black cable, dark mouldings, dark film.
• Pigment where the code has to hold its contrast through outdoor exposure or ultraviolet light over a long service life.
• Dye where the ink has to dry very quickly, or where the code sits on an absorbent surface such as corrugated board or uncoated paper and colour strength matters more than opacity.
• Fluorescent, dye-like chemistry where the point is that the mark is not visible at all: the covert UV cartridge we supply is read under a 365 nm lamp, and its chemistry is deliberately not a visible pigment — see the invisible UV ink.
• Neither, on its own where the surface has not been treated. On PE and PP film the treatment is usually the deciding variable, which is what the note on UV-curable TIJ on PE and PP film is about.

What to send us before you choose

The useful answer here is almost never a datasheet comparison. It is a print on your own material, judged against the thing that actually fails: legibility at the end of the service life, not on the day it was printed.

Send the substrate with any coating or treatment noted, the code content and its size, your line speed, whether the product stops, and what the pack goes through afterwards — a chilled cabinet, a retort, direct sun, a solvent wipe. We will come back with the ink system that fits and a sample to test. If a mark has already failed, start with the adhesion diagnostics; if the job is a date or batch code on a pack, date and batch coding is the closer match.