Quick answer: Watercolour is made from finely ground pigment bound with gum arabic (the sap of acacia trees), plus a humectant such as glycerin or honey to keep it from drying brittle, a wetting agent to help it flow, and a preservative. Artist-grade paint is mostly pigment and gum; student-grade paint adds fillers like chalk or dextrin to cut cost. The paint is milled into a paste, sold in tubes, or dried into pans. The pigments themselves range from ancient minerals (ochres, ultramarine) to modern synthetic organics (phthalocyanines, quinacridones).
Open a pan of watercolour and you are looking at a recipe that has barely changed in 250 years: coloured powder, tree sap, a little sweetener, water. The question “what is watercolour made from” has a short answer and a long one, and the long one explains why one tube costs four times another, why some colours fade and some do not, and why the paint in a child’s set behaves differently from the paint in a professional’s.
This guide walks through each ingredient and its job, where pigments come from, how the paint is manufactured, how grades differ, and how all of this shows up when you paint. Choosing between the many sets available becomes much easier once you know what is in them; the watercolour paint recommendations apply that knowledge to current options.
The Four Core Ingredients
1. Pigment
Pigment is the colour. It is a solid, insoluble powder milled to particles ranging from about 0.1 micron (some synthetic organics) to 10 or more microns (some minerals). Pigments do not dissolve in water; they are dispersed, which is the key distinction from dyes. Dyes dissolve completely and soak into fibres; pigments sit as particles on and just below the surface.
Pigments fall into three families:
- Inorganic natural: mined and ground minerals. Ochres and siennas (iron oxide clays), umbers (iron and manganese oxides), genuine lapis ultramarine, and a few others. These are the oldest colours in human art.
- Inorganic synthetic: minerals made in a factory. French ultramarine (synthesized since 1828), cobalt blue, cerulean, cadmium reds and yellows, chromium oxide green, titanium white, synthetic iron oxides (Mars colours). Generally very lightfast and often granulating.
- Organic synthetic: carbon-based molecules produced chemically. Phthalocyanine blue and green, quinacridones (rose, magenta, gold, burnt orange), perylenes, pyrroles, azo yellows, dioxazine violet. Generally transparent, high in tinting strength, often staining, and mostly very lightfast in modern formulations.
Every pigment has a Colour Index name printed on the tube or listed in the manufacturer’s chart: PB29 is ultramarine, PB15 is phthalo blue, PR122 is quinacridone magenta, PY42 is synthetic yellow iron oxide. The marketing name (Winsor Blue, Prussian Green, Opera Rose) varies by brand; the Colour Index code tells you what is actually inside.
2. Binder: gum arabic
Gum arabic is the hardened sap of Acacia senegal and Acacia seyal trees, harvested mainly in the Sahel region of Africa. Dissolved in water it forms a slightly viscous solution that coats pigment particles, keeps them suspended, and then dries into a thin, transparent, brittle film that adheres the pigment to paper.
Its most important property is that it never cures. The dried film redissolves in water indefinitely, which is why watercolour pans can be reactivated for years and why dried paint can be lifted from paper. Gum arabic is also edible and used in food and pharmaceuticals, which is one reason watercolour is among the least toxic paint media (the pigments, not the binder, carry any hazard).
A few manufacturers use alternative or supplementary binders: dextrin (a modified starch) in some student paints, and a synthetic gum in a handful of lines. These change handling slightly but the principle is the same.
3. Humectant and plasticizer
Pure gum arabic dries hard and can crack or flake, and in a pan it would become nearly impossible to rewet. Glycerin is added as a humectant, drawing a little moisture from the air to keep the paint flexible and the pans soft enough to release pigment to a wet brush. Honey, corn syrup, or invert sugar serve the same role and some brands advertise honey as a feature. Too much humectant makes paint sticky and slow to dry on paper; too little makes pans hard.
4. Wetting agent, preservative, and water
A surfactant lowers water’s surface tension so the paint spreads evenly rather than beading on sized paper. Historically this was ox gall (bile from cattle); most modern paints use synthetic surfactants. A preservative (often a mild biocide) prevents mould in tubes, since gum and sugar are both food for microbes. Water is the vehicle that carries everything and evaporates away.
What Fillers Do and Why Grades Differ
The difference between artist (professional) and student grade is mostly the ratio of pigment to everything else.
| Characteristic | Artist grade | Student grade | Children’s or craft sets |
|---|---|---|---|
| Pigment load | High; as much as the gum can carry | Moderate; extended with fillers | Low; mostly filler and binder |
| Fillers | None or minimal | Chalk (calcium carbonate), dextrin, kaolin, blanc fixe | Substantial chalk and starch |
| Pigment choice | Genuine cadmium, cobalt, quinacridone, etc. | “Hue” versions: cheaper pigments imitating expensive ones | Few pigments, often dye-based |
| Single-pigment colours | Most of the range | Many convenience mixes | Almost all mixes |
| Lightfastness | Rated and mostly excellent | Rated, generally good | Often unrated; may fade |
| Price per tube | Varies widely by pigment (series 1 to 4 or more) | Flat, low | Very low |
| Behaviour | Strong tints, clean mixes, true darks | Weaker tints, slightly chalky, fine for learning | Pale, chalky, limited darks |
“Hue” on a label means the colour imitates a named pigment with a different, cheaper one: Cadmium Red Hue is usually a naphthol or pyrrole red, Cobalt Blue Hue is often ultramarine plus phthalo. Hues are not inferior as paint; they simply have different mixing behaviour and sometimes different transparency from the pigment they imitate.
How Watercolour Paint Is Manufactured
- Dispersion. Dry pigment is wetted with a gum arabic solution and the other liquid ingredients in a mixer until it forms a rough paste. Pigments vary in how readily they wet; some need a specific surfactant.
- Milling. The paste is passed through a triple-roll mill, three steel or granite rollers turning at different speeds with tiny gaps between them. The shear breaks pigment clumps apart so every particle is coated in binder. Multiple passes give a smoother, more consistent paint. This step, more than any other, separates well-made paint from gritty paint.
- Adjustment. The milled paste is tested for consistency, colour strength against a standard, and drying behaviour, then adjusted with more gum, humectant, or water.
- Filling. Tube paint is pumped into aluminium or plastic tubes and sealed. Pan paint is poured as a thicker paste into half-pan or full-pan moulds and dried slowly over days or weeks; some makers pour in several layers to avoid cracking. Lower-cost pans are sometimes pressed from a drier powder mix rather than poured, which is why they can feel chalky.
Where Specific Colours Come From
| Common colour | Colour Index | Source | Notable traits |
|---|---|---|---|
| Ultramarine blue | PB29 | Synthetic sodium aluminium silicate (originally ground lapis lazuli) | Granulating, lifts well, warm blue |
| Phthalo blue | PB15 | Copper phthalocyanine, synthetic organic | Transparent, staining, extremely strong |
| Cobalt blue | PB28 | Cobalt aluminium oxide, synthetic mineral | Granulating, non-staining, expensive |
| Cerulean blue | PB35 or PB36 | Cobalt stannate or cobalt chromite | Opaque, granulating |
| Quinacridone rose | PV19 | Synthetic organic | Transparent, staining, clean mixer |
| Alizarin crimson | PR83 | Synthetic organic (originally madder root) | Transparent, staining, poor lightfastness in genuine form |
| Cadmium red | PR108 | Cadmium sulfoselenide, synthetic mineral | Opaque, non-staining, very lightfast |
| Yellow ochre | PY43 | Natural iron oxide clay | Semi-opaque, granulating, ancient |
| Raw and burnt sienna | PBr7 | Natural iron oxide earth, burnt sienna is roasted | Transparent to semi, lifts well |
| Burnt umber | PBr7 | Iron and manganese oxide earth, roasted | Opaque-ish, granulating, cool brown |
| Hansa or azo yellow | PY3, PY74, PY154 | Synthetic organic | Transparent, bright, lightfastness varies by pigment |
| Payne’s grey | Mix (often PB29 + PBk6 or similar) | Convenience blend | Varies by brand |
| Chinese white | PW4 | Zinc oxide | Semi-opaque white |
Some traditional pigments have been replaced for safety or supply reasons. Genuine lead-based colours are gone from watercolour. Cadmiums remain available but many brands offer cadmium-free alternatives. Natural rose madder and genuine alizarin are still sold but flagged for fading. Mineral violet, Indian yellow, and several others exist today only as hue imitations.
What Is Water Colour and How Is It Used?
In practice, watercolour is this pigment-and-gum paste thinned with water and applied to absorbent paper so thinly that the paper’s whiteness shows through. It is used in three broad ways:
- Transparent washes, layered from light to dark, with highlights left as bare paper. This is the traditional approach for landscapes, botanicals, and illustration.
- Wet-into-wet, where paint is dropped onto wet paper and allowed to spread, favoured for loose, atmospheric work.
- Dry and detailed, with little water and fine brushes, as in botanical illustration and miniature painting, where watercolour behaves almost like a fine opaque medium.
The same paint also serves as a tinting medium for ink drawings, a base for mixed media under coloured pencil or pen, and a colouring medium in design, architecture, and fashion illustration. Its portability and lack of fumes make it the standard medium for sketching on location.
Related Paints Made From Similar Ingredients
- Gouache is watercolour with a higher pigment load and usually added chalk, making it opaque. Same gum arabic binder; rewettable.
- Watercolour pencils and crayons bind pigment in a wax or gum stick that dissolves when wet.
- Liquid watercolours and concentrated inks are frequently dye-based rather than pigment-based, which makes them brilliant but prone to fading and staining.
- Egg tempera uses egg yolk as binder; casein uses milk protein. Both are water-thinned but become insoluble when dry.
- Acrylic gouache and acrylic inks use acrylic polymer and are not rewettable.
Reading a Tube or Pan Label
Most reputable manufacturers print or publish: the Colour Index pigment code(s), a lightfastness rating (ASTM I to III or the maker’s own star system), a transparency symbol, a staining or granulation note, and a series number indicating price tier. A tube listing one pigment code is a single-pigment colour; two or more codes is a mix. “Hue” indicates a substitute pigment. The absence of pigment information on a label is itself information: it usually signals a craft-grade product.
How Composition Shows Up in Painting
- Mixing cleanliness: single-pigment colours mix predictably; multi-pigment mixes can go muddy because three or four pigments are already in play.
- Colour strength: high pigment load means a small amount tints a large wash; filler-heavy paint needs more and still looks pale.
- Granulation: comes from pigment particle size and density, not from the binder, so it is a property of specific colours regardless of brand.
- Staining: small organic particles penetrate paper; large mineral particles do not. Plan which colours go in adjustable first layers accordingly.
- Rewetting: pans with adequate humectant release colour instantly; dry, filler-heavy pans need scrubbing.
- Lightfastness: determined by pigment chemistry. For work meant to last, choose colours rated I or II and avoid fugitive pigments regardless of how appealing they look wet.
Knowing the pigments also makes it easier to build a palette for a particular style of work. Palettes for graphic, high-chroma styles lean on organic synthetics; palettes for traditional and folk styles lean on earths and mineral blues. The pop art palette guide and the folk art palette guide show how the same ingredient knowledge leads to very different colour selections.
FAQs
What is watercolour paint made of?
Pigment (coloured mineral or synthetic particles), gum arabic binder from acacia sap, a humectant such as glycerin or honey, a wetting agent, a preservative, and water. Student grades add fillers like chalk or dextrin.
Is watercolour made from natural ingredients?
Partly. Gum arabic is natural tree sap, and some pigments are mined earths. Most modern pigments, including nearly all bright blues, reds, and violets, are synthetic. Humectants may be natural (honey) or synthetic (glycerin).
What is the difference between artist and student watercolour?
Artist grade has a higher pigment load, genuine pigments, mostly single-pigment colours, and rated lightfastness. Student grade uses fillers, cheaper hue substitutes, and more convenience mixes, giving weaker tints at a lower flat price.
Why is gum arabic used in watercolour?
It disperses pigment in water, dries into a clear film that holds pigment to paper, and remains water-soluble forever, which makes pans reusable and dried paint liftable. It is also non-toxic.
What is water colour and how is it used?
Watercolour is pigment bound in gum arabic, thinned with water, and painted in thin transparent layers on absorbent paper so the white paper provides luminosity and highlights. It is used for washes, wet-into-wet effects, fine detail, tinting drawings, and sketching on location.
Are watercolour pans and tubes made from the same thing?
Yes. Pans are the same paste dried in a mould, usually with a bit more humectant so they rewet easily. Tube paint squeezed into an empty pan and dried becomes pan paint.
Final Thoughts
Watercolour is pigment, gum arabic, a little glycerin or honey, a drop of surfactant, and water, and the price and behaviour of any given tube come down to which pigment and how much of it. Read the Colour Index codes, favour single pigments, and spend on the colours you use most. When you are ready to choose paints with that in mind, the roundup of watercolours for painters compares current sets and open-stock lines by pigment quality, grade, and value.
