No two paints make a true black. What they can make is a colour so dark that on a canvas it reads as black, and unlike tube black it leans somewhere: warm, cool, green, violet. Painters mix their blacks for that lean. A shadow mixed from the same blue and brown as the rest of the painting sits in the picture in a way ivory black rarely does.
What makes a pair work
Pigment mixing is subtractive. Each paint absorbs a slice of the spectrum, and a mix absorbs everything either paint absorbs. Two paints make a near-black when, between them, they absorb almost all of it: a blue that swallows the reds and yellows, plus a brown or red that swallows the blues and greens. The closer to complementary the pair, and the darker each paint is to begin with, the deeper the result.
Six pairs
These were mixed with Halftint's engine from standard tube colours, at the proportions given. The middle column is the distance from a neutral near-black in OKLab units times 100; under 3 is hard to tell apart from tube black. The right-hand column is the same mix let down with six parts of titanium white, which is where the lean shows.
| Pair | Distance from black | Its tint |
|---|---|---|
|
ΔE 6.7 |
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ΔE 3.6 |
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ΔE 6.5 |
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ΔE 6.1 |
|
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ΔE 4.5 |
|
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ΔE 0.9 |
|
| — |
|
A few things stand out. Ultramarine and burnt umber is the classic for a reason: it is the darkest of the earth pairs and its tint is nearly neutral. Ultramarine and burnt sienna is warmer and a shade lighter, and its tint goes to a warm grey. The two phthalo pairs go darkest of all, because phthalo pigments are both very dark and very strong, and their tints show the lean plainly: the phthalo blue pair tints green-grey, the phthalo green and alizarin pair tints to a cool blue-grey. Alizarin and viridian on their own is a dark plum rather than a black; it needs the ultramarine.
Black from a whole palette
If you let the solver use every tube in a palette rather than a pair, this is the closest it gets to a neutral near-black:
Split-primary palette
ΔE 2.8- 2 parts Cadmium Red Light
- 3 parts Alizarin Crimson strong tinter
- 4 parts Phthalo Blue (GS) strong tinter
Target on the left, the colour these parts make on the right. Add in the order listed, strongest pigment last.
Impressionist palette (no black)
ΔE 5.2- 2 parts Viridian
- 5 parts Ultramarine Blue
- 3 parts Alizarin Crimson strong tinter
Target on the left, the colour these parts make on the right. Add in the order listed, strongest pigment last.
Six-tube beginner palette
ΔE 4.2- 3 parts Burnt Sienna
- 6 parts Ultramarine Blue
- 2 parts Alizarin Crimson strong tinter
Target on the left, the colour these parts make on the right. Add in the order listed, strongest pigment last.
None of these is a perfect black, and for painting none of them needs to be. The darkest note in a painting is rarely pure black in life either.
Using a mixed black
Mix more than you think. A dark mix is the batch everything else in the shadows will be tinted from, and running out halfway through a passage means matching it again. Keep the pile to one side of the palette and pull from it with a clean knife. And test the tint before committing: a knife-tip into a little white tells you whether the black you made leans the way the picture needs.