Basic Color Theory for Mixing Secondary Colors

I was reminded of the usefulness of basic colour theory (that's 'color theory' for our american readers :-) )at a nieces birthday party. I was discussing the colour of the icing on the two year old's birthday cake. A helpful (!) neighbour had informed my nieces mother that if she mixed red and blue icing she would get green! Needless to say the purple icing she ended up with was not quite what she wanted (ever seen purple grass?). As a result I figured you might be interested in the following info on basic colour theory(color theory), which you can use when mixing paints, or food colouring.

In theory you only need the primary colours Red, Yellow and Blue to make pretty much whatever colour you want. Traditional 4 colour CMYK printing (Cyan = a blue colour, Magenta = a red colour, Yellow = Yellow(!) and K = Black) adds a black because mixing Red Yellow and Blue tends to give a brownish colour rather than true black. The following list is for *subtractive* colour mixing (like paints and dyes) as opposed to *additive* colour mixing which you get on computer monitors which use Red Green and Blue to create all the colours you see on the screen (thus the acronym RGB).

Anyway, enough background info, here is the table:

  • Red + Blue = Purple
  • Blue + Yellow = Green (use less blue and more yellow)
  • Red + Yellow = Orange (again the red tends to be the stronger colour so use more yellow)
  • Red + Yellow + Blue = Brown

To make secondary colours more pale, thin them down with water (assuming water is being used for the solvent in a paint), or to make them brighter add more yellow (being the lightest of the three primary colours). Likewise, to make a darker secondary colour, add more Red or Blue as appropriate.

If you have any other info you think would be useful to add to this colour/color theory page, drop me an email ( ) and I'll add it in.

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