Since 1832 when Henry Newton and William Winsor introduced the first watercolours to the world, much of Winsor & Newton's reputation has stemmed from the Professional Watercolour range. Since then Professional Watercolour continues to be formulated and manufactured according to Winsor and Newton's founding principles: to create a top-quality watercolour range which offers artists a wide and balanced choice of pigments with excellent permanence.
Professional Watercolour Tubes or Pans
Both Professional Watercolour tube and pan colours are made to the highest standards. Pan colour is often used by beginners because it can be less inhibiting and easier to control the strength of colour. Tube colour is more popular overall, used by artists who use high volumes of colour or stronger washes of colour. Many painters have both - this is because pan colours are useful when travelling and sketching.
Formulation
In simple terms, watercolour is produced by combining (or suspending) a pigment with a binder, for example, Gum Kordofan, a type of Gum Arabic. The formulations for W&N Professional Watercolours are each unique and vary according to the nature and behaviour of each individual pigment. Winsor & Newton rely on expert chemists who have excellent knowledge in understanding and formulating watercolour.
These chemists have learned from the chemists before them who also spent their working lives at Winsor & Newton - since William Winsor died in 1865, they have only had four chief chemists. Thanks to their experience and expert knowledge, they can continue to formulate a high-quality range using the best pigments.
Pigment Choice
Watercolour more than any other medium relies upon the variable characteristics of the pigments used. As it is essentially a staining technique, everything rests on the handling properties of the pigments; whether they can produce a smooth wash or a textured wash; how opaque or transparent they are; the brilliance and strength of their colour; and so on. With this in mind, it has always been - and will continue to be - Winsor & Newton's aim to provide artists with the widest possible range of pigments to give them the greatest choice and flexibility.
Single Pigments in the Range
Wherever possible, single pigments have been used to ensure that Winsor & Newton offer the widest choice of colours and pigment characteristics or positions, such as hue, particle size, transparency, tinting strength, etc. Single pigment formulations are purer in hue and cleaner in colour than mixtures of pigments, providing a larger number of colour mixes before resulting in muddy effects.
Mixed Pigments
Although mixed pigments inevitably lose some degree of chroma or brightness, there are many reasons why they still choose to formulate with them. In some instances, they can achieve a higher level of permanence over a single pigment alternative, e.g., Permanent Alizarin Crimson and Hookers Green. In other instances, some pigments have to be mixed to achieve a given formulation. For example, Quinacridone Gold where the pigment itself is no longer available.
Colour Series
The Professional Watercolour range is split into 4 groups termed 'Series'. The series indicates the relative price of the colour and is determined mainly by the cost of the pigment. Series 1 is the least expensive colour and Series 4 the most expensive.
Colour Range
Winsor & Newton choose their colours according to mass tone (colour from tube), undertone (bias of colour when in a thin film), colour strength, relative opacity and the character of the pigment in watercolour, ie. granulating, staining, or even wash. The resultant colour spectrum ensures the largest number of colours can be mixed from the range.
Transparency & Opacity
Winsor & Newtons Professional Watercolours exhibit excellent transparency due to the unique pigment dispersion in the manufacturing process. As a result of the thinness of the watercolour film, all colours have a transparent quality on paper, allowing the reflective white of the paper to shine through. However, pigments do retain their natural characteristics to some degree. For example, transparent pigments refract light in much the same manner as stained glass, making jewel-like brilliance and clean mixing. Opaque colours such as cadmiums are likely to cover significantly more than transparent colours. The addition of Gum Arabic will also increase transparency. By adding Gum Arabic to a colour wash, you will achieve even greater transparency and luminosity from your washes.
Granulation
Some pigments show a characteristic called granulation, where the way in which the pigment particles settle in the paper creates a mottled effect. For many artists, granulation is highly desirable because it adds texture to their paintings. Even within granulating colours, different effects are apparent when they are brushed out onto paper. Some fine pigments rush together in huddles, more commonly called “flocculation”, whilst other heavy pigments fall into the hollows of the paper surface.
In gerneral, the traditional pigments granulate, e.g., cobalts, earths, ultramarine, etc... The modern organic pigments do not, e.g., Winsor colours. Granulating colours are marked on hand painted and printed colour charts with a “G” beneath the colour chip. They are also detailed in the Colour Charts and the Spectrum Colour Lists. Granulation Medium gives a mottled or granular appearance to colours that usually give a smooth wash, such as Winsor Blue (Red Shade). By adding Granulation Medium to colours that already granulate, such as French Ultramarine, the effect is further enhanced.
Staining
As watercolour relies upon the relative absorbency of the paper surface for stability, more powerful colours such as Prussian Blue, Alizarin Crimson, and the modern organic pigments such as Winsor colours, penetrate or stain more than others. These colours cannot be lifted completely with a damp sponge. The traditional inorganic colours and earths tend to lift more easily from the paper. Those colours that are more likely to stain a surface are marked “St“ on the Professional Watercolour Chart. 
Lifting
Lifting colour entails sponging water colour from a surface. It can include anything from a complete wash down under running water, to getting a “smoky“ background, to the sponging out of a small area in order to lighten or rescue it. Winsor & Newton Lifting Preparation helps ensure that colours, including those that stain, can be more easily lifted from paper with a wet sponge or brush. Lifting Preparation must be applied to the paper first and allowed to dry before removal.