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Pigment Variations

Two brands of Ultamarine Blue side by side

Ask the Expert: “I've noticed something about my tubes of paint: different colors have the same pigment code listed. All shades of Ultramarine seem to have the same PB29, for instance, and several earth colors have PR101. Does this mean the same pigment is in all of them? Is something added to create the different shades and colors?”

A: CII (Color Index International) names are helpful in making a basic “apples to apples” comparison between two brands of the same color of paint, but these codes are not specific enough to distinguish between subtle variations of a single pigment.

Contemporary painters enjoy much better standards for art materials than historical artists. Today, artists' colors are labeled for pigment content, lightfastness and safety, but this wasn't always so.

Historically, colors with the same familiar names might be offered with completely different compositions by different paint makers. At one time, different variations of a color like Ultramarine Blue might have been made of pigments unrelated to either historical (gemstone) or synthetic Ultramarine. Utrecht Professional Artists' Colors are made with tested, Pure Pigments and no adulterants- the colors in our assortment are achieved exclusively by bringing each pigment to its best advantage.

Today, all variations of Ultramarine are made from very similar synthetic silicate pigments produced in kilns. Pigment makers can vary the manufacturing process slightly to create reddish, violet and greenish shades.

Raw Umber, with variations, tints and shades

The CII designation PR101 is used for all synthetic iron oxide pigments, but this code is also used for other chemically similar pigments that fall into this category. Likewise, the natural (terrestrially mined) iron oxide pigments Brown Ochre, Raw Umber and many others are all designated Pbr 7, even though they each have characteristic differences.

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