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How to read an oil paint tube: pigment codes, hues, series and lightfastness

Two tubes called “Cadmium Yellow” from different makers can contain different pigments, different amounts of pigment and different fillers. The label tells you, if you know how to read it. Ten minutes with the small print will save you more muddy mixes than any color chart.

Pigment codes: the only name that matters

Every pigment has a Color Index name: PB29 (Pigment Blue 29) is Ultramarine, PY35 is Cadmium Yellow, PR108 Cadmium Red, PG7 Phthalo Green, PBr7 the sienna/umber family, PW6 Titanium White, PW4 Zinc White. Marketing names (“Permanent Rose”, “Bright Red”, “Sap Green”) vary by brand; the code does not. A single code means a single pigment and the cleanest mixing; two or three codes mean a convenience mixture that will grey faster when you mix it further.

“Hue” and what it means

“Cadmium Red Hue” is not cadmium; it is a cheaper pigment or blend matched to the color of cadmium red in the tube (often PR170 naphthol or PR112). Hues are usually fine in color, weaker in tinting strength and sometimes more transparent. They are why student-range recipes differ from artist-range recipes for the same name — the whole reason PaintMixLab calibrates each set separately. Winton, Magicfly and most budget boxes are mostly hues.

Series and price

Artist ranges group tubes into series 1–6 (or A–F) by pigment cost. Earths and Titanium White are series 1; cadmiums and cobalts series 3–5. Price does not mean quality for your purpose — the cheapest series contains the most useful mixing pigments — but within a brand a higher series number usually means a single, pure pigment rather than a hue.

Lightfastness

ASTM I (excellent) or II (very good) is what you want for anything you intend to keep; III fades within years. Alizarin Crimson genuine (PR83) is the famous offender — most brands now sell “Permanent Alizarin” blends instead. Fugitive colors mix exactly like permanent ones, so this is a durability question, not a mixing one.

Opacity, transparency and drying

A filled square means opaque (cadmiums, Titanium White, Mars colors), an empty one transparent (Ultramarine, Phthalo, Alizarin, Raw Sienna), half-filled semi-transparent. Opaque pigments cover and lighten; transparent ones glaze and darken. Mixing an opaque into a transparent makes the result opaque almost immediately. See the opacity guide. Drying rate is sometimes marked too: umbers, siennas, Prussian Blue and cobalts dry fast; cadmiums, Alizarin, Titanium White and Ivory Black dry slowly — which matters when you paint fat over lean.

Reading the label into a recipe

When you move a recipe between brands, compare codes, not names. If both tubes are PB29 the recipe will be close; if one is PB29 and the other is a “Ultramarine Hue” blend, expect to use more of the hue. If a Magicfly “Viridian” turns out to behave like PG7 (it does), treat it as a phthalo and add it in dabs. The set pages on this site list the recipes already adjusted for each box:

Sage GreenRecipe by paint setTealRecipe by paint setLight Skin ToneRecipe by paint setNavy BlueRecipe by paint set

Questions

What does PB29 mean on a paint tube?

Pigment Blue 29, the Color Index code for Ultramarine Blue. Every pigment has a code (PY35 Cadmium Yellow, PR108 Cadmium Red, PG7 Phthalo Green) and the code is the only reliable way to compare tubes between brands.

What does "hue" mean on oil paint?

That the tube imitates the color of a pigment (for example cadmium) using cheaper pigments. Hues are usually weaker tinters and sometimes more transparent, so recipes written for the genuine pigment need adjusting.

Is student grade oil paint good enough?

For learning and for most finished work, yes. Expect lower tinting strength, more hues and more filler, which means recipes need more of the color and less white than artist-grade versions.
Let the app do the arithmetic
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