[Juan Martinez]

What a fascinating topic: perception of colour. I doubt that I could add any profound knowledge to what has been already said. But, should we not keep in mind that when Karin is speaking of "blue" she means (if I may put words into your mouth, Karin, sorry): when something is to appear blue? That is, when we painters talk about colour, do we not usually mean the effect of the pigment(s) we choose, within a specific visual context? The black and white mixture would not look very blue if it were set against the wrong colours surrounding it, or if it were at the wrong value for the surround, or perhaps, if it were made up of Mars black and white. Of course, a blue swimming pool or a bright blue summer sky is impossible to paint without a blue pigment. But, when juxtaposing colours within the context of a dark, earth tone surrounds, it is often overkill to use a blue pigment--it can look too blue and thereby steal the thunder from the main theme. In the case of Karin's portrait example, that main theme--the portrait's subject--might be overshadowed by the use of a blue pigment. Blues are often a high chroma and have to be greyed-down if they are to be subservient to the main themes of a painting.

In the old days (Renaissance, say) blue was the third most expensive pigment after gold and royal purple. (The only blue available at the time was made of lapis lazuli.) So patrons would usually only ask the artist to use it sparingly--such as in the Madonna's drapery only--and the rest of the time, the artist had to use artifice to achieve the visual effect of a blue. If a patron were to be ostentatious, he would break the bank on blue and gold, just to show how wealthy and powerful he is. Everyone looking at the picture would get the message, because everyone knew these were very, very costly colours. They understood the language of painting much better than the average person does today. But, that's a different topic.

Good painting to all.

Juan