What color combinations are possible using the primary colors of red green and blue?

Answer 1

brown and purple

As there is a fundamental error in your question, let me start by explaining that although red and blue are primary colours green is not. Yellow is the third primary colour of a standard colour pallet. Green is a secondary colour achieved by mixing yellow and blue.

The primary, secondary and tertiary colours as found on a standard colour wheel are as follows:

Yellow - primary

1 part red + 3 parts yellow = yellow-orange (tertiary)

2 parts red + 2 parts yellow = orange (secondary)

3 parts red + 1 part yellow = red-orange (tertiary)

Red - Primary

3 parts red + 1 part blue = red-purple (tertiary)

2 parts red + 2 parts blue = purple (secondary)

1 part red + 3 parts blue = blue-purple (tertiary)

Blue - primary

3 parts blue + 1 part yellow = blue-green (tertiary)

2 parts blue+ 2 parts yellow = green (secondary)

1 parts blue + 3 parts yellow = yellow-green (tertiary)

The mixture of all three primary colours (or a primary and its complimentary secondary colour) usually result in some form of brown.

However, when artists are mixing colour for shaded areas of a painting it is common for them to mix the opposite colour into the shaded area to get dark grey or blackish colour that gives the painting more "life" than the use of true black.

An example of this is when adding deep shade to the leaves of a tree, a very dark shade of the leaf colour is mixed with a small amount of very dark red, to get an almost black shadow.