Two tubes labelled Yellow Ochre can behave very differently in a wash. The pigment code tells you which one you have.
Earth pigments watercolour paints 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, the natural iron oxide. Another might be PY42, made synthetically. They will not wash, granulate or mix the same way.
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 tend to granulate more. PY43 and PBr7 settle into the paper texture in a way that synthetic equivalents often do not. This is useful for atmospheric effects.
PR101 is the workhorse earth red. Transparent, warm, and clean mixing. One of the most versatile colours on any palette and one of the best value artist grade options.
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.
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, tells you the actual chemical pigment inside. PY43 is natural Yellow Iron Oxide. PY42 is the synthetic version of the same nominal colour. Both might be labelled Yellow Ochre. They are not the same paint.
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 marketing. The code is the fact.
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 is natural Yellow Iron Oxide, mined and refined rather than synthesised. It is the pigment behind most traditional Yellow Ochre paints.
PY42 is synthetic Yellow Iron Oxide, made industrially to a consistent specification. It often appears under names like Yellow Ochre or Transparent Yellow Oxide, and it is sometimes used interchangeably with PY43 in brand descriptions online, even though the two are distinct pigments with different particle structures.
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. The difference comes down to how the pigment particle was formed.
Natural pigments like PY43 and PBr7 are mined, then ground and refined. The particles are irregular and vary in size, and that irregularity is what causes granulation, the settling of pigment into the texture of the paper as the wash dries.
Synthetic pigments like PY42 and PR101 are manufactured to a controlled particle size. They tend to sit more evenly in the wash, with less granulation, and often greater tinting strength as a result.
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, for a transparent 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 almost nothing on its own, while PY43 or PY42 printed on the same label tells you exactly what you are getting and how it will behave in a wash.
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
