What is a Color Index code?

It is the standard identifier for a pigment, such as PB29 for ultramarine blue. It tells you what is actually in the tube, regardless of the marketing name on the label.

Where do your pigment facts come from?

From manufacturer color charts and technical sheets, ASTM lightfastness ratings, and established pigment references. We do not list pigment codes from memory.

Why does single-pigment paint matter?

Single-pigment paints mix more predictably and stay cleaner in mixtures. Multi-pigment convenience colors can be useful too, as long as you know what is in them.

What if a manufacturer does not disclose a detail?

We say so. If a formulation detail is proprietary or unpublished, the article states that instead of guessing.

Topic · 6 articles

Pigments & Color Science

Color Index codes, lightfastness, transparency, staining, and granulation explained, plus the color mixing and palette building that depend on them.

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FeaturesNov 6, 202612 min

Granulating Watercolors Explained: 7 Pigments That Settle

Granulating watercolors are paints whose heavy mineral pigment settles into the paper's texture as it dries. Seven that do it, and how to control it.

pigments granulation color-theory

FeaturesNov 2, 202613 min

10 Easy Winter Watercolor Ideas From a 4-Tube Palette

Easy winter watercolor ideas, 10 scenes painted from 4 tubes with no green or white paint. Each lists its colors, pigment codes, paper, time and steps.

watercolor-ideas winter seasonal-watercolor

GuidesOct 19, 202612 min

Rough Watercolor Paper: Granulation, Dry Brush and 6 Steps

Rough watercolor paper is the most textured surface, made for granulation and dry brush. Which weights you can buy, which paints to use, and a 6-step sky.

watercolor-paper granulation dry-brush

FeaturesOct 19, 202612 min

Ceramic vs Plastic Watercolor Palette: 5 Differences

Ceramic vs plastic watercolor palette comes down to how paint pools and how much weight you carry. Beading, staining, sealing and the fixes for new plastic.

watercolor-supplies comparison watercolor-palette

FeaturesOct 17, 202610 min

Student vs Artist Grade Watercolor: 6 Pigments Compared

Student vs artist grade watercolor differs most in pigment load and in which pigments each line uses. Six Cotman and Professional colors compared by code.

watercolor-supplies winsor-newton comparison

GuidesOct 2, 20269 min

Split-Primary Palette Guide: Mix Any Color with 6 Tubes

Split-primary palette uses six tubes, a warm and a cool of each primary. The paints to buy, why they stop muddy mixes, and the formulas for clean colors.

color-theory watercolor-palette pigments

Questions

Frequently asked

What is a Color Index code?: It is the standard identifier for a pigment, such as PB29 for ultramarine blue. It tells you what is actually in the tube, regardless of the marketing name on the label.
Where do your pigment facts come from?: From manufacturer color charts and technical sheets, ASTM lightfastness ratings, and established pigment references. We do not list pigment codes from memory.
Why does single-pigment paint matter?: Single-pigment paints mix more predictably and stay cleaner in mixtures. Multi-pigment convenience colors can be useful too, as long as you know what is in them.
What if a manufacturer does not disclose a detail?: We say so. If a formulation detail is proprietary or unpublished, the article states that instead of guessing.