Earth pigments are colours made from natural or manufactured iron oxides. Ochres, siennas, umbers and earth reds have been part of watercolour palettes for centuries, but their traditional names do not tell you exactly what is in the tube. The pigment code does.
At a glance
Earth pigments are a family, not one colour. Ochres, siennas, umbers and iron-oxide reds cover different pigments and different handling.
The colour name is not the pigment. Yellow Ochre may be PY43, a natural yellow iron oxide, or PY42, a synthetic one. Check the label.
Burnt Sienna is not one fixed pigment. Some versions use PBr7; others use PR101, synthetic red iron oxide. The code matters more than the name.
Handling varies within a code. Pigment origin, milling, formulation and paper affect transparency, texture and mixing.
Earth colours are useful mixers. A blue and an earth colour can make restrained neutrals, but the result is worth testing on your own paper.
| Code | Pigment family | What the code commonly identifies here |
|---|---|---|
| PY43 | Natural yellow iron oxide | Yellow ochre and related natural yellow earths |
| PY42 | Synthetic yellow iron oxide | Manufactured yellow ochres and oxides |
| PR101 | Synthetic red iron oxide | Earth reds and some paints sold as Burnt Sienna |
| PBr7 | Natural brown earth family | Many siennas and umbers |
The earth-pigment family
Earth colours usually fall into three practical groups. Yellow ochres and raw siennas are commonly associated with yellow iron oxides. Umber colours sit within the broad PBr7 earth family. Burnt siennas, Indian reds and Venetian reds can use natural earths, synthetic iron oxides, or different formulations under the same traditional name.
The family map is useful, but the code is the starting fact. PY43 identifies natural yellow iron oxide. PY42 identifies synthetic yellow iron oxide. PR101 identifies synthetic red iron oxide. PBr7 covers a broad group of natural brown earth pigments, including many umbers and siennas.
These codes identify pigment families, not guaranteed handling. For the full Colour Index system, see what watercolour pigment codes actually mean.
Natural and synthetic iron oxides
Natural earth pigments such as PY43 and many PBr7 paints are mined, refined and processed. Their particle shapes and sizes can vary, which may make texture more visible in a wash. This is a tendency, not a promise: the finished paint still depends on formulation and paper.
Synthetic iron oxides such as PY42 and PR101 are manufactured under controlled conditions. They may appear more uniform in a wash, but PR101 is not automatically transparent or opaque. The same code can appear in a transparent earth red or a more opaque red, so the manufacturer’s handling information and a test swatch remain important.
Neither natural nor synthetic is inherently better. The useful question is which version gives the colour, transparency and surface texture needed for the passage.
Choosing earth colours by job
Choose a yellow earth when a landscape or figure needs a muted, warm yellow rather than a bright mixing colour. Choose an umber when you need a cooler brown or a subdued neutral. Choose an earth red when a warm red-brown, brick red or transparent sienna note is useful.
Do not assume that every Yellow Ochre, Burnt Sienna or Raw Umber is interchangeable. Read the code, then test the paint in the way you expect to use it: as a wash, a mix, or a glazed layer.
Mixing earth colours with blues
Earth colours are especially useful with blues because they make restrained greys and neutrals without relying on tube black. An ultramarine and an earth colour can produce a wide range from warm grey to dark neutral, depending on the pigments, proportions and water.
The exact pairing matters. PBr7 and PB29 may give a textured, granulating neutral. PR101 with a smoother blue can produce a more even mixture. Neither outcome is universally preferable. Make a small swatch on the paper you use before relying on a mixture in a finished piece.
This is the earth-colour application of the principle explained in single-pigment watercolours: knowing what is in each tube makes a mix easier to understand and repeat.
The practical verdict
Buy earth colours by the information on the label, not by the traditional name alone. PY43, PY42, PR101 and PBr7 are useful reference points, but they are not performance ratings.
Build a small selection around the jobs you actually paint, then let your own test swatches decide which versions earn a permanent place. Earth pigments reward that patient approach because their apparent simplicity often hides real differences between tubes.