Two tubes labelled Yellow Ochre can behave very differently in a wash. The pigment code tells you which one you have.
Earth pigments in watercolour are sold under a confusing set of names, and two tubes with the same name on the label can contain different pigments entirely. One Yellow Ochre might be PY43, a natural yellow earth. Another might be PY42, made synthetically. They can behave differently in a wash and in mixes.
The fix is simple. Read the code, not the name.
At a glance
The colour name is not the pigment. Yellow Ochre from one brand may be PY43. From another it may be PY42. They behave differently in the wash. Check the code.
Natural earth pigments often show more texture. PY43 and PBr7 can settle visibly into the paper surface, but origin alone does not predict granulation. Milling, formulation and paper all affect the result.
PR101 is a versatile earth-red pigment. It can appear in transparent Burnt Sienna and more opaque reds. The code identifies the pigment family; the manufacturer’s specification tells you how the finished paint handles.
PBr7 covers a range of natural earths. Raw Umber, Burnt Umber, and several others all carry the PBr7 code. The exact behaviour depends on the specific variant and how it has been processed.
Mixing earth pigments with blues produces reliable darks. PBr7 plus PB29 is one of the most useful dark mixes in watercolour. Richer and more controllable than a tube black.
PY43, PY42, PR101 and PBr7 at a glance
| Code | What it identifies | Common labels | Typical handling |
|---|---|---|---|
| PY43 | Natural yellow iron-oxide earth | Yellow Ochre, yellow earth and, in some ranges, Raw Sienna | Often granulating; opacity and strength vary by brand |
| PY42 | Synthetic yellow iron oxide | Yellow Ochre, Yellow Oxide and Transparent Yellow Oxide | Often more uniform in a wash; formulation still matters |
| PR101 | Synthetic red iron oxide | Burnt Sienna, Indian Red, Venetian Red and Light Red | Can range from transparent to opaque; check the individual paint |
| PBr7 | Natural brown iron-oxide earth family | Raw Umber, Burnt Umber and brown ochres | Often granulating; source and processing affect the result |
These codes identify pigment families, not guaranteed handling. A manufacturer’s formulation, milling and pigment load can make two paints carrying the same code behave differently.
Why the same colour name can mean different pigments
Manufacturers name their paints for the market, not for the chemistry. Yellow Ochre, Raw Sienna, Indian Red and Venetian Red are all traditional names, inherited from centuries of pigment trade, and none of them is protected or standardised.
That is why the pigment code matters more than the name printed above it. The code, usually a letter and a number stamped in small print on the tube, identifies the pigment family inside. It does not tell you how finely the pigment has been milled, how much pigment is present or exactly how the finished paint will handle. PY43 identifies a natural yellow earth. PY42 is its synthetic counterpart. Both might be labelled Yellow Ochre, but they are not the same pigment.
Earth pigment naming is inconsistent between brands, and it can vary by market too. A tube called Yellow Ochre in one country’s range may not match the equivalent tube from the same brand sold elsewhere. The name is the label; the code is the better starting fact. For the system behind those letters and numbers, see our guide to how watercolour pigment codes work.
The iron oxide family: PY43, PY42, PR101 and PBr7
Most earth colours in watercolour come from iron oxide, in one form or another. Four codes cover the ground a working painter needs.
PY43 identifies natural Yellow Iron Oxide, mined and refined rather than synthesised. It appears in many traditional Yellow Ochre paints, although colour names still vary between ranges.
PY42 identifies synthetic Yellow Iron Oxide, made under controlled conditions. It often appears under names such as Yellow Ochre or Transparent Yellow Oxide. PY42 and PY43 are sometimes treated as interchangeable in retail descriptions, even though they are distinct Colour Index designations.
PR101 is synthetic Red Iron Oxide. It shows up under a wide range of traditional names, including Burnt Sienna, Indian Red, Venetian Red and Light Red, depending on the brand and the exact formulation.
PBr7 is the broadest of the four. It covers several natural earth pigments, including Raw Umber and Burnt Umber, mined from different deposits and processed in different ways. A PBr7 from one source will not necessarily match a PBr7 from another.
How natural and synthetic earth pigments in watercolour behave differently
Natural and synthetic variants of the same apparent colour are not equivalent, even when the tube uses the same traditional name. Origin is part of the difference, but the finished paint is also shaped by milling, formulation and pigment load.
Natural pigments such as PY43 and PBr7 are mined, then ground and refined. They often retain varied particle shapes and sizes, which can encourage granulation: pigment settling visibly into the texture of the paper as a wash dries. It is a tendency, not a rule for every paint carrying the code.
Synthetic iron oxides such as PY42 and PR101 are manufactured under controlled conditions and can produce a more consistent particle profile. Many sit more evenly in a wash, but PR101 paints alone range from transparent Burnt Sienna to more opaque reds. The manufacturer’s handling information and a test swatch remain more useful than the code on its own.
If you want to understand why two tubes of Raw Umber behave differently, look at the processing as well as the code. PBr7 covers a family of pigments that are mined and processed in different ways. The code tells you the family. It does not always tell you the exact behaviour.
Which earth pigments to prioritise on a working palette
A limited palette does not need every earth colour on the shelf. Three cover most of what a watercolour painter needs.
PY43, for a warm, granulating yellow that anchors landscape and figure work alike.
PR101, in a transparent Burnt Sienna formulation, for a warm red that mixes cleanly and does not muddy easily.
PBr7, in a cool variant such as Raw Umber, for shadow work and neutral mixing without reaching for black.
Together these three give a working painter most of the earth range they will ever need, with room to add specific variants later once the gaps in a particular practice become clear.
Mixing earth pigments with blues: what works and what does not
Earth pigments earn their place at the mixing stage as much as on their own. PBr7 mixed with a granulating blue such as PB29, French Ultramarine, produces one of the most useful dark neutrals in watercolour, richer and more controllable than paint straight from a tube of black.
PR101 mixed with a cooler blue like Phthalo Blue produces a range of warm greys and near black darks, useful for shadow work where a flat black would look dead on the page.
PY43 mixed with blues tends toward muted, earthy greens, useful for foliage and landscape work where a bright green would look artificial.
What does not work as well is mixing two natural granulating pigments together and expecting a smooth flat wash. PY43 and PBr7 both settle unevenly, and combined they can produce a mottled result that some painters want and others do not. Test the combination on scrap paper before committing it to a finished piece.
The practical verdict
Buy earth pigments by code, not by name. A tube labelled Yellow Ochre tells you little on its own, while PY43 or PY42 identifies the pigment family you are buying. Then check the manufacturer’s transparency, granulation and staining information to understand how that particular paint is likely to behave.
Build a working palette around PY43, PR101 and a PBr7 variant such as Raw Umber, and most landscape, portrait and mixed-media watercolour work is covered without further additions. For UK painters comparing options across UK watercolour suppliers, the pigment code should be the first thing checked, not the last.
For a wider look at how single pigments behave and why that matters beyond the earth colours, see the materials section.
What to buy
These are practical starting points for a palette built around earth pigments. Stock and pricing change, so treat the links as supplier starting points rather than fixed product guarantees.
Winsor and Newton Professional
Yellow Ochre (PY43)
Natural PY43. Slightly granulating, warm, reliable earth yellow. One of the most useful colours on a limited palette.
Winsor and Newton Professional
Burnt Sienna (PR101)
Synthetic PR101. Transparent and warm. Mixes cleanly with blues to produce useful darks and neutrals.
Daniel Smith Extra Fine Watercolour
Raw Umber (PBr7)
Natural PBr7. Granulates on textured paper. Useful for atmospheric shadow colours and mixing neutrals without going to black.
Where to buy
