How did artists like Money and Seurat mix colours?

I meant Monet, oops xP x

Well my above answer applies to Seurat. Monet was an impressionists and for them painting was all about capturing light which is reflected in the colours that they used.

Georges Seurat frequently applied unmixed colours to the canvas as small dots ( a technique called “ pointillism “ ), so that the light reflecting off the small dots was mixed in the observer’s eyes, in a manner similar to that used by colour monitor technology - which creates the impression of a full range of natural colours using only the three colours red green and blue. Seurat, however used a wider range of colours.

The normal mixing of paint on a palette produces a change of hue by “ colour subtraction “ ( e.g. Red + Green = Brown and Red + Green + Blue = Black );

A colour monitor produces change of hue by “ colour addition “ (e.g. Red + Green = Yellow and Red + Green + Blue = White );

To a certain extent, Seurat’s use of “Pointillism” utilizes the colour addition effect which creates a sensation of added brilliance / lightness in the hues we experience when his paintings are viewed at a normal (moderate) distance, rather than inspecting them very close up.

– Best wishes - Majikthise