What separates a professional watercolour from a student one is not the colour on the tube but what is inside it: the ratio of pigment to binder, whether that pigment is single or blended, and how honestly the manufacturer documents its permanence and behaviour. A professional watercolour is built to be understood.
Pigment load
Professional watercolour is taken to each pigment's maximum saturation point — hand-mulled until the gum and honey carry all the pigment they can hold. The difference is felt immediately: staining strength, granulation and the richness of a wash laid straight from the tube. Student watercolours cut the pigment with extenders and fillers, which keeps the price down but dulls the chroma and weakens the tinting strength.
Single-pigment formulation
A single-pigment watercolour carries exactly one Colour Index (CII) pigment — Ultramarine Blue is only PB29, Quinacridone Rose is only PV19. Single-pigment colours mix cleanly because only one chemistry is at work on the paper, and they reveal each pigment's true transparency, granulation and staining. Multi-pigment "convenience" colours blend two or more pigments to imitate an expensive or fugitive original; used straight they are fine, but mixed further they muddy quickly.
Disclosed permanence and behaviour
A professional watercolour publishes its lightfastness, transparency, granulation and staining for every colour, so a painter can choose with certainty rather than guesswork. Lightfastness is a property of the pigment, not the brand: the most permanent watercolours use pigments rated ASTM I or II (Blue Wool 7-8). Michael Harding publishes these ratings on every product page and on the tube label.
Honey and hand-mulling
The Michael Harding watercolour range is bound with honey and glycerine, which gives a smooth, rewetting-friendly film and a long open time. Each colour is hand-mulled — the same painstaking process used for the oil range — to bring the pigment to its fullest saturation. Because the range leans toward single-pigment formulation, each tube behaves predictably and mixes cleanly.
How to read a Michael Harding watercolour label
Every tube carries the colour name, the Colour Index pigment code, the series (which reflects the cost of the pigment), and the lightfastness rating. Cross-reference the pigment code with the product page to see the full transparency, granulation and staining data. If a label carries no pigment code at all, the manufacturer has not disclosed the contents and you cannot verify how the colour will mix or age.
Explore the full range on the Watercolours page, or let the Watercolour Set Finder build a tailored set from the live catalogue to match how you paint.