NOTE: The manufacture of most iron oxide artists' paints, including those with traditional names such as "earth", "sienna", "umber" or "ochre", has changed from the use of natural iron oxide clays — designated by the generic color index names PBr7 or PY43 — to the use of synthetic iron oxide powders. Small supplies of artists' grade natural iron oxides continue to flow from mines in Europe and the Middle East, but by 2002 there were no longer any suppliers of natural iron oxide pigments registered with the Society of Dyer's and Colourists' (UK) Colour Index.

Many watercolors now labeled PBr7 or PY43 are actually made of mixed synthetic iron oxide pigments, not natural ores. In fact, iron oxides used in watercolor paints today include pigments formulated for use in wood or leather stains, or as plastic, ceramic or masonry colors, and are available in a very broad range of colors and grades. See for example the page "earth tones dry pigments" at the web site of Kama Art Materials (Montréal, Québec), the mineral and iron oxide pigments available at Sinopia Pigments (San Francisco, CA) or Kremer Pigments (New York, NY), and the pigment information pages at Société des ocres de France or their USA distributor, The Earth Pigments Company (Tucson, AZ).

The use of natural oxides has dwindled so much that in 2001 the SDC considered eliminating the color index names PBr7, PR102 and PY43 from the Colour Index, and reassigning these pigments to the color index names for synthetic brown (PBr6), red (PR101) or yellow (PY42) iron oxides. However, manufacturers lobbied to retain these color index names as convenient "color" designations and desirable marketing labels. In 2007, the SDC reaffirmed to me that they were still deliberating on the issue.

For the Daniel Smith line of Primatek™ "genuine" mineral pigment paints, which are not assigned a color index name, see this page.

Calcinated synthetic iron oxide black PBr6 is a lightfast, very opaque, very staining, near black, near neutral brown pigment, available from 20 pigment manufacturers worldwide. Unrated by the ASTM, my 2004 lightfastness tests gave it a "very good" (II) rating, with some fading in tints after 6 weeks of sunlight exposure. The CIECAM J,a,b values for iron oxide black (PBr6) are: 17, 5, 4, with chroma of 7 (estimated hue purity of 7) and a hue angle of 38.

M. Graham van dyke brown was the only single pigment source in watercolors. The Daniel Smith sepia adds black pigment to darken the paint; a touch of phthalo blue (PB15) will produce the same result. A darker and slightly cooler alternative to burnt umber, and very interesting as a diluted glazing paint — which is how Baroque artists used the original van dyke or cassel browns. See also the section on red earth pigments.

TOP 40 PIGMENT  Natural iron oxides, all labeled PBr7, constitute a family of very lightfast pigments that have played a long and important role in human art and crafts. Red and yellow ochres were used as a ritual cosmetic in human burials as early as 20,000 years ago; the calcinated forms were probably discovered when iron colored clays were first fired in kilns about 8,000 years ago (6,000 BCE).

Iron oxides can be any of several colors, including earth yellow, earth orange, earth red, brown or black, depending on (1) the quantity of trace manganese, aluminum or silica in the pigment; (2) the size of the pigment particles; and (3) whether the pigment is in its hydrated form (contains some water in the iron oxide crystal) or is calcinated ("burnt" or roasted) in kilns or foundry ovens, which drives off the water. This means that two paints made with PBr7 can have very different color appearance, and any paint containing PBr7 may actually be a mixture of two, three or four iron oxides pigments, each with a different color, blended to match a specific color target. If you want to geek out on these color variations, this earth pigments tour should do the trick.

The many shades of PBr7 pigments have been rated with "excellent" (I) lightfastness by the ASTM, and all manufacturer tests agree. My 1998 tests found problems with a few synthetic iron oxides, as discussed below, but (with one exception) not with the natural oxides listed here. Otherwise they vary widely in handling characteristics (opaque to semitransparent, nonstaining to heavily staining, very dull to moderately intense, mid valued to very dark valued) depending in part on particle size, composition and vehicle formulation.

Paints made with these pigments can undergo a small to very large drying shift, losing saturation by more than 20% and lightening up to 30% in the darker pigments (burnt umber and dark raw umbers); light shades of raw umber or burnt sienna show moderate to very small drying shifts. They also make a substantial hue shift toward yellow from masstone to undertone.

Historically, the highest quality artists' pigments came from clays collected in Italy (especially around Siena), Cyprus and the Middle East (imported to Europe by Venetian merchants); the origin of the ores often gave specific colors their geographic names. (See the section on natural iron oxides for details on current sources of the pigments.)

These early pigments converged on a quartet of traditional natural iron oxide hues that are very useful and still manufactured today:

• RAW SIENNA. Traditionally a mid valued, moderately dull earth yellow, slightly granulating, nonstaining and semiopaque to semitransparent. In the brands rated here the average CIELAB LCh (lightness, chroma, hue angle) values are 63, 56 and 66. This earth color varies substantially across manufacturers; some paints are a pale yellow trivially different from yellow ochre (PY43), while others are a grayish brown. Daniel Smith monte amiata natural sienna is a warm mid valued yellow brown, my favorite single pigment example of the raw sienna color, with a slight tendency to darken in masstone. MaimeriBlu raw sienna is a rich color that is uncharacteristically staining; either it is a finely divided pigment or a synthetic organic yellow has been added. The Rembrandt raw sienna is also warm and light. Other single pigment brands of raw sienna are various shades of brown — to my taste too brown to be a good raw sienna. These include a greenish dark brown close to a yellow ochre (Rowney Artists and, darker still, M. Graham), a warm light brown (Daniel Smith and DaVinci), a toffee brown (Utrecht, still a lovely color full strength), a middle grayish brown (Old Holland). The average CIECAM J,a,b values for raw sienna (PBr7) are: 55, 23, 42, with chroma of 48 (estimated hue purity of 39) and a hue angle of 61. See also the raw siennas listed under PY42 and PY43.

• BURNT SIENNA. A dark valued, moderately dull earth orange, lightly staining, and semiopaque to semitransparent. The average CIELAB LCh values are 45, 46 and 42. The less intense versions of this earth color have typically deepened to a warm, moderately dark brown, and are more opaque. This is one of the most versatile and useful paints, an excellent mixing complement for blues from ultramarine blue to cerulean blue, and a great partner with blue green and green pigments for mixing natural, dull yellow greens. M. Graham burnt sienna is an especially rich but regrettably opaque example of the light chocolate brown that is characteristic of most modern burnt siennas (MaimeriBlu, Daniel Smith, Utrecht, Holbein are all very similar). Daniel Smith monte amiata burnt sienna is a lighter, more saturated orange variation of burnt sienna that is very versatile in mixtures, particularly for greens and muted yellows; their "burnt sienna," "italian burnt sienna" and "pompeii red" are minor variations on the basic color. The Rowney Artists burnt sienna is an overly bright and warm color, uncharacteristically staining (probably a finely divided wood stain pigment) but also transparent. The average CIECAM J,a,b values for burnt sienna (PBr7) are: 37, 40, 27, with chroma of 48 (estimated hue purity of 36) and a hue angle of 35. To get the optimal transparency and chroma, some companies opt for synthetic iron oxides, listed as burnt sienna or transparent red iron oxide under PR101.

• RAW UMBER. Originally the umber ores came originally from Turkey. The name probably derives from the Latin ombra or shadow, referring to their use as shadow pigments in Renaissance painting, and not from the Italian city of Umbria. The best color is a transparent, dark valued, grayish or greenish (very dull) earth brown close to the hue of yellow ochre (yellow orange). The average CIELAB LCh values are 42, 26 and 64. Today raw umbers is manufactured to a consistent deep yellow hue, but with large brand variations in chroma and lightness, from a dull olive color to a warm light gray to a dark cool gray (as discussed in the earth pigments tour). Modern brands tend to be staining and semitransparent (indicating very small particle size), and most make an excellent neutralizing complement for ultramarine or indanthrone blue. I feel this paint should not have a distinct yellow or brown appearance, but instead present a greenish, medium to dark gray: the raw umbers by Daniel Smith, M. Graham, Rowney Artists and Utrecht all meet this expectation. The new Winsor & Newton raw umber is lighter, with a warm fawn color that lacks the characteristic raw umber coolness of the discontinued in paint. The average CIECAM J,a,b values for raw umber (PBr7) are: 34, 12, 20, with chroma of 23 (estimated hue purity of 24) and a hue angle of 59.

• BURNT UMBER. The darkest of the four earths, a very dark, very dull earth brown, staining and semiopaque, with a color resembling dark chocolate (orange hue). The average CIELAB LCh values are 36, 24 and 48. Currently this earth color is manufactured to a consistent yellow orange hue, and varies across brands on chroma and value. Daniel Smith burnt umber is an almost black coffee brown that runs an enticing span of colors as it is diluted into tints; Utrecht and MaimeriBlu are similar colors, but differ in handling characteristics. Winsor & Newton burnt umber is the same hue but lightened with the addition of synthetic red and yellow iron oxides, which makes the brown more saturated; M. Graham burnt umber nearly matches it using only pigments labeled PBr7. The average CIECAM J,a,b values for burnt umber (PBr7) are: 28, 18, 16, with chroma of 25 (estimated hue purity of 21) and a hue angle of 42.

These earth blends, along with pure red iron oxide (PR101) and yellow iron oxide (PY42) have been important paints in the watercolor tradition. These "colors" differ substantially from one watercolor brand to the next, so sampling these pigments on your own is necessary to understand their range and capabilities.

As a group, the iron oxides are usually easy to apply but sometimes take a longer to rinse from a brush. Mixtures with earth paints are easier to edit by rewetting and reworking with the brush, and staining pigments painted over them are also easier to lift or edit, making the iron oxides an excellent foundation mixture for flesh tones in portraits or figures. They harmonize and blend well with almost any other type of pigment, and buffer or reduce the tinting strength of synthetic organic pigments (quinacridones, phthalocyanines) and the strident color of cadmium paints. Just remember to stir the mixtures with each brush load, as the iron oxides tend to sink to the bottom. Applied in dilute washes, they make effective and very reliable landscape foundation tints. The more transparent brands (such as Winsor & Newton and Maimeri) are also effective as glazes to adjust existing color areas. (Note that some of the "transparent" red or yellow iron oxides, for example those by Rembrandt or Daniel Smith, are actually semiopaque and granulating.) As with any dark or dull pigment, you should experiment with the full range of paint dilutions and color mixtures to evaluate the paints' color and handling attributes.

I suggest you start by buying all four earth colors from a single manufacturer, as the better brands contrast the earth paints interesting ways; then after working with those paints add or replace paints as you prefer from other brands. The Winsor & Newton and MaimeriBlu are especially colorful (well contrasted in hue and value), but the M. Graham and Rembrandt versions are also well designed and worth investigating for a darker interpretation of the colors.

Since 2002 Daniel Smith has substantially augmented their selection or iron oxide pigments, which is now the largest earth color range available in watercolors and worth careful review, although most are variations on the color concepts described here and under the red (PR101) and yellow (PY42, PY43) iron oxides. In addition to the natural earth quartet, natural iron oxides have been used for their color and lightfastness to simulate a variety of historical but fugitive natural organic pigments — sepia and van dyke brown in particular. These paints are usually made with carbon black, are very staining, and can be dull in heavy applications. See also the section on red earth pigments.

NOTE: See the comments at the top of this page regarding natural iron oxide pigments.

Magnesium ferrite PBr11 is a very lightfast, opaque, lightly staining, moderately dark valued, moderately dull earth orange pigment, available from only two pigment manufacturers worldwide. Unrated by the ASTM, my own and manufacturer lightfastness tests give it an "excellent" (I) rating. It is a slightly chalky light brown similar to many burnt siennas, but with very noticeable flocculation or channeling in wet applications. (For a similar color see the zinc magnesium ferrite PY119.) The CIECAM J,a,b values for magnesium ferrite brown (PBr11) are: 40, 36, 32, with chroma of 48 (estimated hue purity of 35) and a hue angle of 42.

Daniel Smith lunar earth is apparently the only commercial source; the paint is relatively inert wet in wet, and blossoms lightly when rewetted. A remarkable texturing brown pigment, and an excellent complement to ultramarine blue (PB29): the two mix to make stunning, very textural browns, grays and moody dark blues. See also the section on magnesium pigments.

Chrome titanate PBr24 is a very lightfast, opaque, staining, moderately light valued, moderately intense earth yellow pigment, available from about a dozen pigment manufacturers worldwide in shades ranging from green yellow through orange yellow (the shade currently used in watercolors) to dull red. The ASTM (1999) rates its lightfastness as "excellent" (I), and my own and manufacturer lightfastness tests agree. It was originally developed as a vinyl siding pigment that would weather gracefully under prolonged sunlight exposure. In watercolors PBr24 undergoes a very small drying shift, darkening by 5% and losing saturation slightly. The average CIECAM J,a,b values for chrome titanate (PBr24) are: 68, 24, 48, with chroma of 53 (estimated hue purity of 39) and a hue angle of 64. In watercolor paints described here the pigment is consistently a warm pale yellow; paints differ only in the milling and vehicle formulations.

Of the brands tested, Winsor & Newton naples yellow deep is slightly smoother textured, more saturated, more staining, and is more active in wet applications; the Schmincke pigment shows a subtle flocculation in washes. — This is a very beautiful, pale golden yellow, lighter and slightly less saturated than (but exactly the same hue as) hansa yellow deep (PY65). It retains its glowing character from full strength to tints. It has naturally whitened color and can be used as a weak bodycolor for any mixtures requiring an opaque yellow. I prefer it to raw sienna, which in modern formulations may have permanency problems. Definitely worth trying for florals, botanicals, and warm landscapes; also mixes very interesting, intense flesh tones. See also the section on titanium pigments.

Benzimidazolone brown PBr25 is a very lightfast, transparent, heavily staining, dark valued, moderately dull brown pigment, available from two pigment manufacturers worldwide. Unrated by the ASTM, my own and manufacturer lightfastness tests give it an "excellent" (I) rating. As it is a dark valued, finely divided synthetic organic, it shows a fairly large drying shift. The average CIECAM J,a,b values for benzimidazolone brown (PBr25) are: 31, 34, 21, with chroma of 40 (estimated hue purity of 32) and a hue angle of 32.

Daniel Smith permanent brown is the only commercial source in watercolors; the paint is moderately active wet in wet but has only moderate tinting strength. There is a reddish tint to this pigment that makes it resemble a diluted indian red in moderately light applications; the lightest tints take on a pinkish flesh color.

An interesting pigment, with good mixing potential with blues, violets and all warm colors, but most of its mixing potential can be found in other paints, most obviously with a dark burnt sienna. Not an essential pigment, but its transparency and tinting strength make it worth exploring for landscape and portrait palettes. See also the section on benzimidazolone pigments.

Zinc iron chromite brown PBr33 is a very lightfast, very opaque, staining, very dark valued, very dull brown pigment, available from about 7 pigment manufacturers worldwide. Unrated by the ASTM, my own and manufacturer lightfastness tests give it an "excellent" (I) rating. It is a handsome blackish brown in masstone with an ethereal bluish gray glow, caused by the separation of differently colored coarse and fine pigment particles, in tints or backruns. The average CIECAM J,a,b values for zinc iron chromite brown (PBr33) are: 25, 12, 8, with chroma of 14 (estimated hue purity of 12) and a hue angle of 33.

Schmincke walnut brown is the only commercial source; the paint is inert wet in wet but blossoms energetically when rewetted, with interesting textural effects in dilute washes. An interesting pigment, similar to a cool burnt umber, but with greater textural possibilities and a very large hue shift in tints. Even so, its distinctive character makes it hard to work into a painting. Harmonizes well with ultramarine blue and lunar earth (see above under PBr11) in limited palette paintings. But otherwise not an essential pigment. See also the section on zinc pigments.

Disazo condensation brown PBr41 is a very lightfast, semitransparent, heavily staining, very dark valued, moderately dull brown pigment, available from only one manufacturer worldwide, Clariant GmbH. Unrated by the ASTM, my own and manufacturer lightfastness tests give it "excellent" (I) lightfastness, with slight fading in the tint. The average CIECAM J,a,b values for disazo condensation brown (PBr41) are: 29, 33, 21, with chroma of 39 (estimated hue purity of 31) and a hue angle of 32.

Schmincke translucent brown is the only commercial source. The paint is relatively inert in wet applications. The pigment is almost identical in all respects to benzimidazolone brown (see above under PBr25), except that it bronzes slightly in masstone. See also the section on disazo condensation pigments.

Van Dyke brown NBr8 is a marginally lightfast, semiopaque, heavily staining, black valued, neutral dark earth brown pigment, one of many pigments (Cologne earth or Cassel earth) traditionally made from surface deposits of peat or lignite (brown coal). Unrated by the ASTM, it's widely recognized as a fugitive pigment; my tests put it in the "fair" (III) category, making it unsuitable for watercolors. Holbein van dyke brown is the only commercial source; the color consists of a dark, brownish gray pigment with a grayish black ash; the two pigments separate slightly in wet applications, and the brown fades in light, leaving the gray ash.

AVOID. Most companies match this antiquated pigment with a natural iron oxide mixed with lamp black (PBk6); but excellent single pigment alternatives include M. Graham vandyke brown, MaimeriBlu burnt umber, or the raw umbers by Daniel Smith, Rowney Artists, Utrecht or M. Graham. Many of the modern convenience substitutes, such as Winsor & Newton van dyke brown, offer a color that is too intense and homogenous to make a good match. See also the section on natural organic pigments.

earth color paints made with pigments in a different color index category

TOP 40 PIGMENT Quinacridone orange PO48 is a lightfast, transparent, staining, moderately dark valued, moderately intense earth orange pigment, available from 3 registered pigment manufacturers worldwide, and primarily used as an automotive color. The ASTM (1999) rates its lightfastness in watercolors as "very good" (II); however, manufacturer and my own tests rate it "excellent" (I). In watercolors PO48 undergoes a moderately large drying shift, lightening by 10% but dropping almost 30% in saturation. The average CIECAM J,a,b values for quinacridone burnt orange (PO48) are: 42, 52, 37, with chroma of 63 (estimated hue purity of 48) and a hue angle of 35.

This quinacridone is a mixed crystal phase of beta quinacridone (PV19) and quinacridone quinone, nearly identical to the hue of "dull orange" (rather than brown) burnt siennas by Winsor & Newton or Rowney Artists (see the color comparisons in the earth pigments tour for more details).

The pigment provides a transparent alternative to orange iron oxide earths (e.g., burnt siennas) that mixes well with a wide range of other paints. Full strength it has a dark orange color that lightens to a dull scarlet, marvelous for sunset skies, desert cliffs and tanned skin; it shifts toward a pastel deep yellow in tints. It is relatively unresponsive in wet applications, and its transparency makes it marvelous for mixing subdued sap greens and dark blues. Well worth investigating. See also the section on quinacridone pigments.

Initially, Daniel Smith quinacridone burnt orange was the sole source for this pigment in watercolors, but now several paint brands, including DaVinci, M.Graham and Winsor & Newton include it as a single pigment paint.

Substitutes: The color, transparency, lightfastness and handling characteristics of both PO48 and PO49 can be matched very closely by a suitable mixture of nickel azomethine yellow (PY150) and a synthetic organic red or red violet such as perylene maroon (PR179), quinacridone rose (PV19) or quinacridone violet (PV19). A close substitute can also be mixed from green gold (PY129) with quinacridone magenta (PR122).

In 2004, based on information from a paint chemist, I alerted that the last manufacturer of PO48 may cease production because of insufficient demand. Eight years later, pigment retailers, such as Kremer Pigmente, continue to carry PO48, and paint manufacturers report no change in supply from their manufacturers.

 Quinacridone gold PO49 is a lightfast, transparent, staining, mid valued, moderately intense earth yellow pigment. Manufacture of PO49 ceased in 2001 because there was insufficient demand for the pigment from automobile manufacturers, its principal consumers. Most artists' paints made with this pigment were discontinued in 2005. See the note below on substitute mixtures.

PO49 is another mixed crystal form of PV19 alpha and beta. The ASTM (1999) rates its lightfastness in watercolors as "very good" (II); manufacturer and my own tests rate it "very good" to "excellent" (I). In watercolors PO49 undergoes a moderate drying shift, darkening slightly and losing roughly 20% saturation. The average CIECAM J,a,b values for quinacridone gold (PO49) were: 52, 33, 50, with chroma of 60 (estimated hue purity of 47) and a hue angle of 56. Most paints show active diffusion of fine particles and subtle granulation in wet applications. The paints redissolve and lift fairly easily, making the natural earth pigments preferable for foundation tints.

Beacuse PO49 is a proprietary pigment, all the paints listed here were very similar in color with a finely divided consistency. In masstone the Daniel Smith paint darkens almost to a glowing orange (a hue similar to benzimida orange PO62 but less saturated), and in tints the hue shifts to a warm middle yellow (hue angle 75, the color of "yellow" raw siennas). In 2005 Maimeri replaced the quinacridone pigment with a gold iron oxide (PY42), although their web site and paint packaging continue to assert the ingredient is PO49; Winsor & Newton has replaced their PO49 with a mixture based on nickel azomethine yellow as described under PY150.

Quinacridone gold is an excellent alternative to gold ochre (PY42) and moderately dull yellows such as nickel azomethine yellow (PY150) or the less lightfast anthrapyramidine yellow (PY108). It mixes well with nearly all other paints and produces transparent sap green mixtures. See also the section on quinacridone pigments.

Substitutes: The color, transparency, lightfastness and handling characteristics of both PO48 and PO49 can be matched very closely by a suitable mixture of nickel azomethine yellow (PY150) and a synthetic organic red or red violet such as perylene maroon (PR179), quinacridone rose (PV19) or quinacridone violet (PV19). A close substitute can be mixed from green gold (PY129) with quinacridone magenta (PR122).

Nickel red PO65 is a lightfast, semiopaque, nonstaining, dark valued, moderately intense earth red pigment, offered by only 2 pigment manufacturers worldwide. Unrated by the ASTM, industry and my own lightfastness tests give it an "excellent" (I) rating. The average CIECAM J,a,b values for methin nickel scarlet (PO65) are: 33, 59, 25, with chroma of 64 (estimated hue purity of 55) and a hue angle of 23.

Old Holland golden barok red is apparently the only source in watercolors; their paint has a lovely clumping granulation in wash applications and is fairly inert wet in wet, but it blossoms readily and easily lifts or bleeds if rewetted. This is another of those unique pigments that the chemists at Old Holland delight in bringing to watercolor paints. Its dark brownish red is not unlike blood as it begins to coagulate, though the comparison slights its beauty. Much less brown than PR175, and tending toward PR176 in masstone. A very lovely pigment worth trying for yourself. See also the section on metal complex pigments.

TOP 40 PIGMENT  Synthetic red iron oxide PR101 is a very lightfast, opaque to transparent, staining, dark valued to very dark valued, moderately dull to dull earth orange, earth red or brown pigment (the variations in color and transparency arise from differences in pigment particle size, metal additives and hydration). Widely used in cosmetics, pharmaceuticals, construction (it's the red in red bricks), industrial paints, automotive finishes, plastics and artists paints, it is offered by more than 30 pigment manufacturers worldwide in a broad range of formulations.

Synthetic red (PR101) and yellow (PY42) iron oxide pigments are refinements on the natural iron oxides (see PBr7, above), apparently first manufactured by alchemists but not used in artist materials until the 17th century and not manufactured in large quantities until the 18th century. Because they are made of iron (the metal of war), alchemists gave them the generic name "Mars" — including mars violet, mars brown, mars red and mars yellow (PY42). The synthetic red iron oxide pigments vary widely in hue, from brick red to dull purplish brown; some are calcinated (burnt or roasted) in foundry ovens to modify their color. (If you want to geek out on the color variations, this earth pigments tour should do the trick.)

In watercolors PR101 undergoes a moderate drying shift, holding its lightness but losing saturation by 20% or more. The extremely small and consistent particle sizes possible with synthetic materials makes the dull (concentrated) pigments very opaque and the intense (diluted) pigments very transparent, and all are smooth and usually staining. Added chemicals such as manganese can be controlled precisely, so there tends to be less variation in the standard PR101 hues across manufacturers than there is in the natural earths; and manufacturing variation of the color has induced paint makers (Daniel Smith in particular) to add several new hues to the red earth range. Indeed, this ample selection makes "hue" paints adjusted with synthetic organic pigments superfluous, and I suggest you avoid them: the pigments can separate wet in wet or in the tube after long storage.

The ASTM (1999) has rated the lightfastness of all shades of PR101 as "excellent" (I), and all manufacturer and my own tests agree. However, my 1998 tests suggest that some synthetic iron oxides may present problems. After six weeks of summer sunlight exposure, my samples of Winsor & Newton raw sienna (listed under PY42 below) and both MaimeriBlu transparent mars red and transparent mars brown had all grayed noticeably; Daniel Smith raw sienna blackened in masstone.

These problems may arise because of unusual impurities in the manufacturers' pigment stock, or they may be a consistent attribute of these pigments. But as the samples indicate, they appear across too many paint brands to ignore. If you have any concerns, conduct your own lightfastness tests.

The red iron oxide pigments are marketed in a few standard color categories or color concepts, with some fanciful marketing variations. The main types are:

• VENETIAN RED. A reliable dark, dull orange red, moderately to very opaque, and formerly made with natural red iron oxide. In the brands listed here the average CIELAB LCh (lightness, chroma, hue) values were 39, 38 and 33. (The names English red and light red traditionally referred to slightly yellower pigments made from synthetic red iron oxide; now all pigments are synthetic and these names have mostly a marketing purpose. See PR102.) The hue of this paint is extremely consistent across manufacturers; nearly all the color variations are limited to value, chroma and opacity. Winsor & Newton venetian red is reliable and not too opaque, but offers more body and a pinker color than a transparent burnt sienna. This is the dead on best neutralizing complement for iron [prussian] blue (PB27), a traditional combination especially preferred by Winslow Homer. Venetian red (or indian red) is also interesting in mixtures with cerulean blue, which produce an interesting range of violet tinged grays. The average CIECAM J,a,b values for venetian red (PR101) are: 31, 37, 19, with chroma of 42 (estimated hue purity of 34) and a hue angle of 28; for light red (PR101) are: 33, 38, 24, with chroma of 44 (estimated hue purity of 35) and a hue angle of 32.

• INDIAN RED. A slightly duller and more violet version of the red iron oxide, also very opaque. The average LCh values were 41, 37 and 32. In good paints the hue takes on a purplish cast, on the road to mars violet. Winsor & Newton produces perhaps the largest contrast between this paint and venetian red. The average CIECAM J,a,b values for indian red (PR101) are: 33, 37, 18, with chroma of 41 (estimated hue purity of 34) and a hue angle of 26.

• TRANSPARENT RED. A slightly darker valued and more intense color, with an appearance close to a burnt scarlet. Offered by few paint manufacturers, the actual transparency of this "transparent" pigment depends on the brand; some paints are semiopaque. A few brands of burnt sienna, including Rowney Artists and Winsor & Newton, are also made with a transparent red iron oxide.

• TRANSPARENT BROWN. A dark valued brown close to many burnt umbers. Again, the actual transparency of this "transparent" pigment depends on the brand; some paints are semiopaque.

Because the pigment particles are so fine, PR101 pigments tend to stick in a brush and can be strongly staining. A thick layer of paint will lift and muddy a second paint layer glazed over it, but dilute applications produce a reliable, rosy or fleshy foundation tint. They can be dulled when mixed with staining pigments such as the phthalo blues. They work well with other opaque pigments, especially the cadmiums or chromium oxide green, but tend to separate from the cobalts when applied in juicy mixtures. Use them in tints up to moderate dilution; lay down the earth colors (such as venetian red or gold ochre) before the granulating pigments (such as cobalt blue or viridian); work with lighter, yellower colors first, then the darks; and use plenty of water — these paints can glow when sufficiently diluted! See also the section on iron pigments.

Natural red iron oxide PR102 is a very lightfast, semiopaque to transparent, nonstaining, moderately to very dark valued, moderately to very unsatured earth orange pigment (the variations in hue and value arise from different pigment formulations). Unrated by the ASTM, my own and manufacturer lightfastness tests give it an "excellent" (I) rating. It is another calcinated natural iron oxide that is a completely lightfast, semitransparent, nonstaining, mid valued, moderately dull earth orange pigment; the burnt version is warmer than the half burnt.

This pigment was once known under the name light red, which Winsor & Newton reintroduced in 2005 to replace the former paint made by mixture. The Old Holland versions have the trademark near complete lack of staining, but otherwise resemble pale burnt siennas with poor tinting strength. Useful to replace light red or burnt sienna when complete lifting is required, but otherwise not preferable to the iron oxide paints discussed under PBr7 and PR101. See also the section on red earth pigments.

NOTE: See the comments at the top of this page regarding natural iron oxide pigments.

Benzimidazolone red PR175 is a very lightfast, semitransparent, staining, dark valued, moderately intense earth red pigment, manufactured by Clariant GmbH. Unrated by the ASTM, manufacturer and my own tests show "excellent" (I) lightfastness. Despite the name, I've classified it with the earth colors because it has a reddish brown color from masstone to tints. The average CIECAM J,a,b values for benzimidazolone scarlet (PR175) are: 31, 50, 26, with chroma of 56 (estimated hue purity of 47) and a hue angle of 27.

Daniel Smith deep scarlet is apparently the only commercial source of this pigment. The paint has a lovely rich color in masstone, transparent and moderately active in wet applications. — A darker and slightly more chromatic alternative to the umber earths, roughly in between the value, saturation and hue of perylene maroon (PR179) and quinacridone maroon (PR206). Not an essential pigment, but probably useful to landscape and portrait/figure painters. See also the section on benzimidazolone pigments.

TOP 40 PIGMENT  Quinacridone maroon PR206 is a lightfast, semitransparent, moderately staining, dark valued, moderately intense earth red pigment, available from only two pigment manufacturers worldwide (primarily as an automotive color). It is a mixed crystal of PV19 and quinacridone quinone, very close to the hue of the traditional and fugitive pigment brown madder. The ASTM (1999) rates its lightfastness in watercolors as "very good" (II), but in my own 2004 lightfastness tests it showed "excellent" (I) lightfastness. In watercolors PR206 undergoes a moderate drying shift, lightening slightly but losing over 20% of its saturation. The average CIECAM J,a,b values for quinacridone maroon (PR206) are: 36, 54, 25, with chroma of 60 (estimated hue purity of 50) and a hue angle of 25.

Daniel Smith quinacridone burnt scarlet is the darkest and strongest tinting paint tested here, a beautiful scarlet brown; it is very similar to the MaimeriBlu avignon orange, which tends to bronze slightly when applied full strength. The Winsor & Newton paint stains less and is slightly more saturated, but is also lighter and seemingly less concentrated.

PR206 is a very attractive color for botanicals, portraits, or landscapes. It is an unusually versatile neutralizing complement with a wide range of blue and blue green pigments, from iron blue (PB27) to viridian (PG18). It adds a slight granular texture to the phthalocyanines and complements the granular texture of the cobalts; it creates evocative dark mixtures with dioxazine violet, hansa yellow, and indanthrone blue. Its major drawback is its relatively weak tinting strength; other dark pigments can overpower it; for that reason I prefer perylene maroon (PR179). An excellent glazing pigment to cut the saturation of cool hues or to build warm shadows; very easy to handle overall. See also the section on quinacridone pigments.

Chrome aluminum stannate PR233 is a lightfast, semitransparent, moderately staining, moderately dark valued, dull earth red pigment, manufactured as a decorative ceramics colorant under the trademark Sicocer F Pink by BASF (Germany) and sold to the artist's trade by Kremer Pigments. Unrated by the ASTM, chemistry and prior use plausibly puts it in the "excellent" (I) lightfastness category. The CIECAM J,a,b values for pinkcolor (PR233) are: 42, 34, 16, with chroma of 38 (estimated hue purity of 31) and a hue angle of 25. Historically used since the 18th century as a watercolor pigment, under the name "pinkcolor".

TOP 40 PIGMENT  Synthetic yellow iron oxide PY42 is a very lightfast, opaque, staining, light valued to moderately dark valued, moderately intense to dull earth yellow pigment, available from about 30 pigment manufacturers worldwide. Rated as having "excellent" (I) lightfastness by the ASTM and paint manufacturers, I found in my 1998 lightfastness tests that several brands of synthetic yellow iron oxides turned slightly dark or gray in masstone (see the color notes under PR101 for more information). The color varies widely across watercolor manufacturers due to variations in the impurities included in the iron and in the raw pigments used; see the earth pigments tour for clarification. In watercolors PY42 undergoes a very small drying shift, holding its value and losing 10% or less in saturation. The average CIECAM J,a,b values for mars yellow (PY42) are: 53, 24, 44, with chroma of 50 (estimated hue purity of 41) and a hue angle of 61; for gold ochre (PY42) they are: 50, 37, 45, chroma 58 (estimated hue purity 44), and hue angle 51.

The manufactured variations in this pigment have produced some interesting paints. Winsor & Newton gold ochre is a distinctive, reddish gold color (the same hue as benzimida orange, PO62, at lower chroma) that lends a subtle texture to wet in wet passages, a fabulous landscape and figure nude paint. The Winsor & Newton raw sienna is a warm, light yellow that is one of the most transparent versions of this color. Daniel Smith transparent yellow oxide really is transparent, and nonstaining as well, a subtly granulating, dark, toasted yellow color — but test its lightfastness for yourself. Daniel Smith mars yellow or MaimeriBlu yellow ochre are a different color entirely: darker, almost greenish, and much more opaque (note the MaimeriBlu bronzes when applied full strength). I like any of these paints in place of other raw siennas or the more opaque yellow ochre, which are more common watercolor artists' choices for an earth yellow. All resemble raw sienna in tints, but at full strength show a distinctive character; all mix very well with phthalo greens or blues to produce natural, dull greens. See also the section on iron pigments.

 Natural yellow iron oxide PY43 is a very lightfast, semiopaque to semitransparent, nonstaining to moderately staining, mid valued to moderately dark valued, moderately dull to dull earth yellow pigment, now available from only 2 registered pigment manufacturers worldwide. The variations in transparency, staining, granulation and activity wet in wet across the the brands listed here are reflected in color variations as well, which is not captured in the average CIELAB LCh (lightness, chroma, hue) values, 67, 59 and 69. These paints are all a deep yellow hue identical to nickel dioxine yellow (PY153). The ASTM, paint manufacturers and my own tests rate this pigment as having "excellent" (I) lightfastness. In watercolors PY43 undergoes a very small drying shift, decreasing slightly in saturation. The average CIECAM J,a,b values for yellow ochre (PY43) are: 58, 22, 45, with chroma of 50 (estimated hue purity of 40) and a hue angle of 64.

This has been the most popular choice for an earth yellow for the past two centuries at least. I suggest approaching the paint offerings as consisting of four basic color choices:

• My prejudice is that the classic yellow ochre should be rather dark and have almost a greenish cast; this separates it from the warmer, sunnier raw sienna. The M. Graham, Rowney Artists, DaVinci and Rembrandt paints represent this style; Maimeri's yellow ochre (under PY42) is also in this group. These paints are often the most opaque but brighten nicely in tints.

• Some paints take on a warmer, lighter yellow color, including the yellow ochres by Utrecht, Winsor & Newton and Daniel Smith.

• Other paints are warm and dull enough to appear almost reddish brown, such as Daniel Smith italian deep ochre. This paint is rather thin and is the most transparent.

•  Finally there are a few pale, weakly tinting ochres, including two relatively new paints, Winsor & Newton yellow ochre light and Daniel Smith verona gold ochre, which appear to contain the same pigment (though the Daniel Smith has a slightly better tinting strength).

These various yellow ochres, though traditional and still common in oil painting, have less to recommend them in watercolors. Some artists find natural yellow iron oxide is oily or sticky on the brush, hard to rinse, and tends to sink out of wash mixtures (especially greens mixed with phthalo green), requiring frequent stirring. For those reasons they prefer synthetic yellow iron oxide (PY42) or raw sienna (which has, however, a weaker tinting strength). I tend to share this view. However, ochre is a remarkable foundation pigment, providing a warm glow to paints glazed over it, and an earth yellow works exceptionally well with a synthetic organic crimson and synthetic inorganic blue to create glowing and easily adjusted flesh mixtures. Also, there is an interesting variety in the earth yellow pigments not called "yellow ochre," and it may be worth the time to try such paints from different brands. See also the section on yellow earth pigments.

NOTE: See the comments at the top of this page regarding natural iron oxide pigments.

Zinc magnesium ferrite PY119 is a very lightfast, very opaque, slightly staining, moderately dark valued, moderately dull earth orange pigment, available from 7 pigment manufacturers worldwide. Unrated by the ASTM, my own and manufacturer lightfastness tests give it an "excellent" (I) rating. The average CIECAM J,a,b values for mars yellow (PY119) are: 43, 34, 38, with chroma of 50 (estimated hue purity of 39) and a hue angle of 48.

The two paints listed here are very similar, although I much prefer the new Winsor & Newton vehicle formulation. The color is a unique caramel brown, yellower than a burnt sienna but much warmer than an ochre, that shifts in tints to a hue resembling gold ochre; the paint is moderately active in wet applications. The main drawback to this pigment is its opacity, which rivals that of venetian red. In tints it is a lovely color and can replace burnt sienna in some situations provided transparency is not an overriding requirement. See also the section on iron pigments.

KEY TO THE PAINT RATINGS. Summarized as numbers: Tr = Transparency: 0 (very opaque) to 4 (transparent) - St = Staining: 0 (nonstaining) to 4 (heavily staining) - VR = Value Range: the value of the masstone color subtracted from the value of white paper, in steps of a 100 step value scale - Gr = Granulation: 0 (liquid texture) to 4 (granular) - Bl = Blossom: 0 (no blossom) to 4 (strong blossom) - Df = Diffusion: 0 (inert) to 4 (very active diffusion) - HA = Hue Angle in degrees of the CIELAB a*b* plane - HS = Hue Shift as the undertone hue angle minus the masstone hue angle, in degrees of the CIELAB a*b* plane - Lf = Lightfastness: 1 (very fugitive) to 8 (very lightfast) for paint in tint,full strength - Mentioned in pigment notes: Chroma: For the masstone paint on white watercolor paper. - Drying Shift: Change in masstone color appearance from a glistening wet to completely dry paint swatch, in units of lightness, chroma and hue angle in CIELAB. For more information see What the Ratings Mean.

Last revised 07.I.2015 • © 2015 Bruce MacEvoy