Single-Pigment vs Mixed Pigments: A Practical Comparison for Cleaner Colour Mixing

Squeeze out two tubes labelled "ultramarine blue" from two different ranges and you may be holding two quite different paints. One is a single pigment, ground on its own. The other is a blend, built to land on the same hue for less money and with more consistent behaviour in the factory. Both will paint a decent sky. Only one will mix the way you expect when it meets a yellow, a red or a white.

That difference explains a great deal of the mud, the chalky tints and the surprisingly dull greens that turn up on otherwise sensible palettes. It is also one of the easiest things in painting to check before you spend any money: the information is printed on the tube.

What the label is really telling you

Most manufacturers print Colour Index codes on the tube, usually in small type near the colour name. These are internationally standardised, so PB29 means ultramarine blue whoever made it, and PR108 means cadmium red.

• One code — a single-pigment paint. "Ultramarine blue PB29".
• Two or more codes — a blend. "Blue (PB29, PW6, PB15)" is a blue that has been lightened with titanium white and pushed with phthalo blue, probably to hit a price or a target hue.

Colour names, by contrast, are marketing. "Burnt sienna" from one brand might be PBr7 on its own; from another it can be PBr7 with a black and a yellow added to make it more consistent and more opaque. Neither is dishonest, but they will behave differently under the brush, and the tube tells you which you have.

Why pigment count changes your mixes

Every paint you pick up brings all of its pigments into the mixture. Two blended paints can put four pigments in your tray before you have made a single adjustment. The more pigments in a mix, the more opportunities they have to cancel one another out. Chroma drops, the mixture drifts towards grey or brown, and you get a tone you did not ask for.

Single pigments are not automatically better paint. A badly made single-pigment colour can still be gritty, weak or over-priced. What they give you is a cleaner starting point: fewer variables, more predictable shifts each time you add the next colour, and a much better chance of finding your way back to a mix you liked last week.

A habit worth forming

Before you mix, glance at the labels and count. If the aim is a vivid secondary — a clear green, a glowing orange, a true violet — try to build it from single-pigment paints. Save the blends for when you actively want what they do.

When single-pigment paints win

• Clean secondaries. A single-pigment yellow such as PY154 with a single-pigment blue such as PB29 walks steadily through clear greens. Swap either for a blended version and you often arrive at olive or sludge before you intended to.
• Vivid oranges and violets. A single-pigment magenta or crimson (PR122, PV19) with a warm single-pigment yellow gives luminous oranges you can control step by step. Mix a blended red with a blended blue and the violet tends to brown out.
• Glazing. Transparent single pigments layer predictably. Blends that include an opaque white or an earth will cloud a glaze even when the swatch looked clear on the card.
• Repeatable recipes. If you write down "PY154 + PB29, two to one", you can rebuild that green in any brand, any year. Recipes built from blends are far harder to reproduce.
• Tints with white. A single pigment mixed with titanium white stays clean and bright as it lightens. Pigments that already contain black or earth go grey and lifeless in the same tint.

When mixed pigments earn their place

Blends are not a compromise you should feel guilty about. They do jobs that would otherwise eat your painting time.

• Convenience colours. Payne's grey, sap green, Hooker's green and many "indigo" mixes are classic blends. You could build them yourself, and sometimes you should, but a tube is quicker and consistent.
• Hue substitutes. Cerulean hue, cadmium red hue and similar names are blends designed to imitate an expensive or unavailable pigment. Modern versions are usually made from lightfast components, but check the codes rather than assuming.
• Earths and darks. Many burnt umbers, muted greens and dark browns are blended to be more opaque and more uniform from batch to batch.
• Economy and consistency. Student ranges lean on blends because they keep costs down and colours stable. For sketchbook work and underpainting, that is often exactly what you want.

One thing to watch: a blend is only as reliable as its least lightfast pigment. If one code in the list is a known weak performer, the whole tube carries that weakness, however good the others are.

Test a new tube in ten minutes

1. Write the pigment codes on a scrap of paper and keep it with your swatches.
2. Squeeze a small amount next to the paint you already use for that job and compare strength. Some pigments are three or four times as strong as others.
3. Mix a tint with titanium white and let it dry. Clean and bright, or grey and flat?
4. Mix it with its nearest neighbour — a blue with a yellow, a red with a blue — and see how quickly it heads towards mud.
5. Label the dried swatches with the brand, colour name and codes. Do this consistently and you will stop re-buying paint you do not get on with.

Traps to avoid

• Assuming the same colour name means the same paint across brands. It rarely does.
• Blaming your brushwork for mud that is really coming from pigment count.
• Replacing your whole palette with single pigments at once. Change one colour at a time and notice what actually improves.
• Darkening with black. It kills chroma fast; a complementary colour or a dark single pigment such as a deep transparent brown usually serves better.
• Believing "artist quality" always means single pigment. It does not. Read the codes.

Choosing for your palette

A workable approach is to keep the mixing core of your palette single pigment and let the blends handle specific jobs. That usually means a warm and a cool of each primary, plus titanium white, all single pigments — enough to mix a wide, clean range. Then add the blends you genuinely use: a convenience green for foliage, a Payne's grey for quick darks, a hue substitute if the real pigment is out of reach.

If you are unsure, test before you commit to a large tube. Buy the small size, swatch it against what you already own, and let the dried paint make the argument. Over a year or two, that habit will leave you with a palette where every tube has a reason to be there — and where the greens, violets and skin tones come out clean because you chose the pigments rather than the names.

Photo: Antoni Shkraba / Pexels