Student versus Artist Watercolours - Cotman versus Professional Water Colour

Per my last post, many new to watercolouring are advised to use the most expensive paints they can afford, based on high-quality paint yielding high-quality results and thus making it easier to enjoy what one is doing early on. I established in my last post that the Cotman brand of watercolours from Winsor and Newton were, in my experience, superior to the Aquafine brand from Daler and Rowney, as far as student-grade watercolours go. But what about professional watercolours? Well, before I even think about tackling a comparison of a range of brands of artist-quality paints, let's start by comparing student grade and artist grade.



My comparison of Cotman and Professional Water Colour, both from Winsor and Newton, are in Episode 2 of my YouTube series. I compare two paints both based on the pigment dioxazine violet (PV23) - Cotman 231 Dioxazine Purple and Professional Water Colour 733 Winsor Violet (Dioxazine). In terms of the actual colour, they are chemically identical - why they differ is the binders used, the presence of fillers in the Cotman paint, the pigment load (grams of pigment per gram of paint) and how much (if any) humectant is present and, sometimes, what that humectant is. A lot of artist quality paints use honey rather than (or as well as) glycerol, for example. I compare the paints in terms of their properties alone and when mixed with a yellow (which will desaturate the purple to give a grey/black) - I used Professional Water Colour 108 Cadmium Yellow, which is a two-pigment paint, made up of cadmium yellow (PY35) and cadmium orange (PO20) - in the Professional Water Colour range, the single-pigment cadmium yellow (PY35) is 118 Cadmium Yellow Pale.