This section gives assessments for certain determinable characteristics of all the colours presently in my range, as well as a few informal remarks on their qualities and idiosyncrasies when used. Following the pattern already laid out on all my tube and can labels, and on my more recent colour charts, I give:
- The Colour Index Number: This is an international system for classifying and identifying pigments solely by their (often very complex) chemical formulae( e.g P(igment) R(ed) 106, Mercuric Sulphide known as Genuine Vermilion). The use of vague traditional or invented colour names is thus clarifi ed, and so, in theory at least, is the vexed matter of what pigments manufacturers actually put into their paints. If a colourman is honest, each constituent pigment in a paint can be specifi ed precisely, and the practice of secretly adulterating or even completely substituting cheaper alternatives is made impossible. Assuming, that is, the colourman is honest…I can certainly state that there are no secret additions to any of the paints in my range. What you read as the C.I number on the label is what you get.
- Estimated Relative Drying Speed: Bearing in mind that all drying speeds will be affected by temperature, humidity and light levels, these give a broad calibration of comparative speeds, from the Very Fast, such as the Umbers, many of which, if used neat, will be touch dry within a hot summer day, to the Very Slow, which in unmixed state, might take up to a week.
- Transparency: This characterizes the ability of a given paint to cover over the substrate onto which it is painted. At the extreme of opacity there are the Cadmiums, at that of transparency, the Indian Yellows. Transparency should not be confused with sheer strength of colour, or tinctorial/ tint power, as it is revealed in mixes. Some transparent paints, e.g. the Phthalo Lakes, are ferociously strong when mixed with sturdily opaque ones.
- Lightfastness: This gives some indication of the resistance of a pigment to fading when exposed to very high light levels. Though the commonly used numerical system for this is the scale devised by the American Society of Testing and Manufactures (ASTM I-V), in practice the fade resistance of pigments is greatly affected by their concentration, or lack of it, in paint mixes. Thus an excellently lightfast pigment (ASTM I), if dispersed in a paint by addition of fillers, will in consequence show increased tendency to fade. As I have said before, there are no fi llers added to the pigments in my paint range.
- Oil Content: This indicates broadly how much oil has to be ground in with the dry pigment or the lake dye in order to make it into a workable paint. A paint with high oil content will generally, but with exceptions, dry to a glossier surface; that with a low oil content will be leaner.
- Toxicity: This should be taken seriously if you want a long and healthy relationship with my paints. More advice is given in the Health and Safety section of Our website.