Why colour on a dark shirt needs white under it

Put yellow ink straight onto a black shirt and it comes out olive. Put red on navy and it comes out brown. The ink is doing exactly what it was made to do — the fabric underneath is doing the rest.

The fix has a name, and knowing it explains a lot about why printed garments look the way they do.

What is a white underbase?

A layer of white printed first, in the shape of the design, with the colours printed on top of it.

Ink on fabric isn't fully opaque. A single pass of colour lets some of the garment's own colour show through and mix with it, which is why the same yellow looks bright on cream and muddy on black. Laying down white first gives the colour a neutral ground to sit on, so it reads as the colour you drew rather than as the colour plus the shirt.

That's the whole mechanism. It's the reason a good print on black can look as bright as one on white, which otherwise seems like it shouldn't be possible.

Do I have to ask for it?

Normally not — it's a production decision rather than a design one.

Worth being clear about, because a lot of printing advice is written for people operating the machine and then leaks into advice for people designing. Whether a design needs an underbase, how heavy it should be, and which technique gets used at all follow from the design and the garment, and they're decided by whoever is printing rather than specified by whoever drew it.

What reaches you is the composited preview on the real garment colour, which is the thing that actually answers "will this look right".

Does it change what I should design?

Only in one way, and it's a positive rather than a restriction: design for the ground.

A dark garment isn't a white one with the lights off. It's a colour, and the good designs on dark shirts use it — cream line work with the black showing through as the second colour, a subject whose shadows are simply the shirt, negative space doing work that would need ink on white.

That's a compositional choice available to you, and it's more interesting than treating the garment as a background to be covered. The garment colour is half the design either way.

Are there colours that can't be printed?

That question has a history worth correcting.

There's a whole genre of advice that says neons can't be printed, fine white lines will fill in on dark cotton, and so on. Those statements describe the limits of one particular technique, and they get repeated as though they were physics.

They aren't. Printing technique is an axis, not a constant — heat transfer, screen, direct-to- garment, foil, dye, embroidery are all different processes with different strengths, and picking between them is a production decision. Which means a limitation you read about somewhere is usually a limitation of the process that article's author happened to use.

So why does anyone talk about underbase at all?

Because it explains a visual difference you can see, and because it costs something.

An underbase adds a layer, which adds thickness and a small amount of stiffness where the ink sits. That's part of why a heavily printed dark shirt has more hand-feel to it than a light one with the same design, and why very fine detail behaves differently on dark than on light.

Knowing that is useful. Acting on it isn't your job — the thing to avoid is treating one process's constraints as your design brief.

Does it affect how the print ages?

Somewhat, and honestly this is where general internet advice is least reliable.

Durability depends on the technique, the ink, the fabric and how the garment is washed, and the interactions are specific enough that blanket claims are usually wrong. What is reliably true is the boring part: heat and friction are what age a print, which is why cold water and a drying rack do more than anything else.

Anything more specific than that would be a claim about a process, and process is not a fixed property of every order.

What should I actually take from this?

Two things.

One: a bright design on a dark garment is normal and expected — the muddiness you might imagine has a solution, and the solution is applied on this side.

Two: when you read that something "can't be printed", check whether the person is describing a limitation of their equipment. Most of the received wisdom about printed garments is a description of one workshop's setup, frozen into a rule.

How do I order?

Pick the design at JustOG, choose the garment colour, and see the design composited on the real thing before ordering. It's made to order and shipped.

Designs other people have published are in the shop.

The yellow goes olive because the shirt is showing through. Everything after that is our problem.