It is a fancy way of saying there are more crayons in the box. Here is what the extra ones actually do on a shirt, which colors they reach, which colors nothing reaches, and why the name a supplier gives their version of it is just a name.
Printing has always worked by mixing a small number of inks. Four of them, usually: cyan, magenta, yellow and black. Every other color on the page is those four laid over each other in different amounts. It is a box of four crayons that you are allowed to press on top of one another.
Expanded gamut means adding more crayons. Not more of the same ones — new ones, in specific places, chosen because mixing the first four falls short exactly there. On our press those extra inks are an orange and a green.
That is the whole idea, and it is worth saying what it is not. It is not a process anyone invented and kept. It is not a secret, it is not a trademark, and it does not make a press able to print every color you can imagine. It moves the edge of the box outward in two places and leaves it where it was everywhere else.
Crayons add color; ink takes it away. Every ink removes some of the light the shirt would otherwise reflect, so two inks on top of each other are always darker than either one alone. That is why the hard colors are the bright ones, not the dark ones — a press can usually reach the hue you want, but only by giving up some of the brightness you wanted with it.
Four-color printing has three colored inks. Every hue in between two of them is made by overprinting, and an overprint always lands inside the straight line between the two inks that made it. Draw the inks around a color wheel and join them up, and the boundary is not a circle. It is a polygon, and it sags inward between every pair.
There are three sags. An expander ink is, literally, an ink put into one of them.
Four process colors
The six corners are what four inks can reach on their own — three inks, plus the three colors you get by printing two of them over each other. Join them and the boundary is straight lines, which means it sags inward between every pair. The deepest sag is blue-violet.
With two expander inks
An orange and a green are inks placed in two of those sags, so the boundary is pushed back out there. Blue-violet has no expander on our press, and that is why the one color people most often ask about is the one that moves.
Schematic. Hue angles are drawn to typical printing values; the figure shows the shape of the problem, not a measurement of our press.
The widest gap on the wheel with no ink in it — from cyan round to magenta is well over a hundred degrees of hue, and everything in between is two inks laid over each other. That overprint is not just duller, it is dark: it reaches its best color down at the lightness of a navy. A royal blue wants to be chromatic and light at the same time, and four-color process will sell you one or the other.
Magenta over yellow gets to a respectable chroma but cannot hold it where an orange wants to live, which is high and bright. The overprint buys the hue and pays in lightness.
Cyan over yellow drags toward teal and downward in lightness, because cyan carries blue in it. Saturated mid-greens are the classic four-color miss.
Two of the three get an ink. Blue-violet does not, on our press or on most others, and that is the honest reason a royal blue is the color customers ask about most and the one that moves most. We would rather you read that here than discover it on a box of shirts.
Our press runs eight ink channels. That number gets quoted a lot in this industry and it is worth knowing what it does and does not mean, because not every channel is there to add color.
Cyan, magenta, yellow and black — the set every press has, and the one that decides the overall shape of what can be printed.
An orange and a green, each sitting in a region where mixing the process inks falls short. They push the boundary outward in those two places and nowhere else.
Diluted versions of inks the press already has, used so pale tones and soft gradients lay down smoothly instead of grainy.
Opacity and adhesion. It goes under the color so the garment does not mix into every hue, and it carries the powder that bonds the transfer to the shirt.
So a channel count answers the question “how many ink lines does this machine have”, which is not the question anyone means to ask. The one they mean is how much color it can reach, and the answer to that is the shape in the diagram above, not a number.
Three things get asked for that no amount of expanded gamut delivers. These are not hard cases. They are a different category, and a supplier who tells you otherwise is selling you a disappointment with a lead time on it.
A fluorescent colorant absorbs light you cannot see and gives it back as light you can, so it reflects more than it receives. No mixture of ordinary inks does that at any channel count. It needs fluorescent ink, which is a different inkset.
The effect is specular — it depends on light bouncing off a metal surface at an angle. That needs a metallic colorant or a foil process, not more color.
A neon on a monitor is a bright value sitting next to a dark interface, lit from behind. Half of what you like about it is the backlight and the surround. Nothing on a shirt sits next to a black backlit field.
You will see branded names for this. Someone's special color system, with a trademark on it and a page explaining how vivid it is. Expanded gamut printing is the state of the art, and a name applied to it is a name. What is actually on the press is a set of inks, and what matters is which ones and what the operator does with your file.
The claim worth recognising is the color count: sixteen point seven million colors, or some number like it. That figure is how many values an ordinary 8-bit image file can hold. It describes the file on your screen. It says nothing whatever about a printer, and no press resolves anywhere near that many distinguishable colors on film. When a supplier quotes it, they are quoting your own file back at you.
The questions that separate suppliers are smaller and more boring. Does anybody look at the file before it prints? Does anyone tell you which of your colors will move, before you pay, or do you find out when the box arrives?
Everything above is what a shop needs. What follows is the real machinery, for people who want it.
The set of colors a press can print is a three-dimensional shape in a color space called CIELAB: lightness up the middle, hue around it, and intensity outward from the neutral axis. “More colors” properly means a bigger volume and a different shape, and a volume comparison means nothing unless you also say what it is being compared against, on what material, with how much ink and under which conversion. We have not measured ours, so we publish no figure for it. The measurement that would settle it is a printed chart read with a spectrophotometer, and when we have one we will say what it said.
A color is described by three numbers: how light it is, how intense it is, and which hue it is. The boundary of what a press can print is best written as the most intensity available at a given lightness and hue — which is why a color can be out of reach for three different reasons. It can be too intense, or too light, or too dark for the hue it is trying to be. The fix is different in each case, which is why “just desaturate it” is sometimes exactly wrong.
A blue
A yellow
Each hue reaches its strongest color at its own lightness: the blue slice is widest low down, the yellow slice high up. That is why a royal blue cannot also be bright, and why a vivid yellow is hard to reach in a different way — it is already as light as ink gets.
Schematic. The dashed arrow is what our preview models — intensity reduced, lightness held. The solid one is closer to what the press does, giving up a little lightness to keep more of the color.
Our preview reduces intensity and holds lightness and hue where they are. It answers one question honestly: this vivid blue becomes that duller blue. A press does something more sophisticated — it gives up a little lightness too, and compresses neighbouring colors together so the relationships in the artwork survive.
That difference has a direction, and it is worth knowing which way: our preview is pessimistic about bright light colors, because the ink version of a yellow or a lime is darker than the screen version and we do not model the trade. Read the overlay as a map of where attention is needed, not as a verdict on each color.
Total coverage across the channels is capped, and on film the practical ceiling is lower than on paper: wet film can only carry so much before the powder stops keying properly and the cure suffers. The darkest, most saturated corner of any gamut is bounded by that, not by how many channels the press has. More inks do not mean more ink.
A conversion has to decide what to do with colors it cannot reach. Perceptual compresses everything a little so relationships survive. Relative colorimetric leaves reachable colors alone and clips the rest to the boundary, which can flatten detail inside a saturated area. Saturation favours vividness over accuracy. Absolute also reproduces the paper white of the source, which is wrong for garments. These are decisions the press makes, not switches you set.
A spot color in a vector file is a named separation carrying three things: a name, a fallback color space, and a function mapping a tint from nothing to full strength. The press matches the name against its own color book and uses the recipe it holds for that color, which can draw on every channel. If the name does not match, the fallback is evaluated instead — which is a different color, arrived at honestly, and the reason a hand-named swatch is a gamble.
Getting the most out of color has the exact steps for building one that matches.
There is a standard measure of how far apart two colors are, and you will see it quoted. On its own it is uninterpretable. It depends on which formula was used, under which illuminant and observer, with which measurement condition, comparing what against what, on which material, and whether the figure quoted is an average, a maximum or a worst case. A supplier quoting a bare number for it is quoting a number.
Ours, where you see it in the studio, is the distance between the color in your file and our modelled reproduction of it. It is a distance between two numbers, not a measurement of a printed sheet, and we would rather label it that way than let it imply more.
No, and we would rather say so. It is established practice in commercial printing and it is where serious DTF production has gone. What differs between suppliers is what they do with it — whether anyone looks at your file, and whether anyone tells you which of your colors will move before it prints.
The name is the part that is proprietary. A trademarked label on an inkset is marketing, not a technology; what matters is which inks are on the press and what the operator does with your file.
That number is how many values an 8-bit RGB file can hold. It describes the file on your screen, not the press, and no printer resolves anywhere near that many distinguishable colors on film. A supplier quoting it is quoting your own file back at you.
Fluorescent and neon colors, metallics, and the deep blue-violet region are the honest answers. The first two need a different kind of colorant altogether. The third is the weakest part of four-color printing and the one region our expander inks do not cover.
It is an ink channel, but it adds no color reach. White is there for opacity and for the bond — it stops the garment mixing into every hue and it carries the powder that holds the transfer on. Counting it toward color is the same move as counting the values in a file.
No design printed in ink matches an emissive screen exactly, and a monitor that has never been calibrated is not a defined target in the first place. The realistic goal is the closest printable color to the value in your file, and knowing in advance which ones will move.
The practical companion to this page is Getting the most out of color, and the color mode question — RGB files, CMYK files, and what we do with each — is covered in Common file issues and how we fix them.
Upload a design and the studio marks the colors that will move before you order anything.
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