Colour and Pigment The Science Of Colour – Natural paints do not look the same as modern non-natural paints. There are scientific reasons for this which are fascinating but complicated, so in summary, for those who want to understand more. Here are some key scientific reasons why colours can seem different. Colour and how we perceive it The science of colour in paint making is about paint ingredients – how natural paint is made, the behaviour of light and how the colour spectrum works with the human eye. This is all about the binder! Plastic binders have a huge impact in how the colours look, natural binders are much softer, calmer, gentler on the eye. How we see pigment We do not see colours made only from natural earth and mineral pigments in the same way as colour made from synthetic azo dyes because the light is reflected from them very differently. Natural pigments produce a richer and more nuanced colour. We just use 12 natural pigments, including black and white, to make all 102 colours. Our natural pigments With an understanding of the physics of light and colour we can examine how paints and coatings are coloured and how different types of colouration are achieved. The big change in modern paint manufacturing is that most companies have replaced natural pigments with azo dyes which are rather bland. Texture and colour If the surface of the sample is very smooth, light will be reflected from that smooth surface like a mirror at the same angle and with the same spectral range. This affects the appearance of the colour, the higher the gloss, the darker the colour appears whereas a textured surface with the same pigmentation will appear to be of a lighter shade. Measurement of colour Attempts to measure and classify colours according to human perception has a long history, however since the invention of photo-spectrometers clear and objective measurement of colour can be achieved. But people will always see colour differently. Other influencing factors on colour Scattering of light by pigments, transmission of light through the paint film, scattering co-efficient of a pigment, pigment load of a paint film, thickness of the paint film. Edward’s favourite conversation is about Metamerism…… Metamers are colours that can look the same under one set of conditions but different to one another under others. When the spectral curve of two colours crosses in at least thee places metamerism is likely. Under different light conditions the difference in colour becomes apparent. This is why synthetic colours can look quite different in artificial light as opposed to daylight.
