No matter how I describe it paint is a subtractive colour method. There may be some argument for light passing through layers of glaze but it still ends up being a subtractive colour method. If two glazes are trying to subtract colours from the same spectrum of light falling on the canvas then the resulting colour will be muddy brown or almost black. If we get other results it’s because the paint is so inefficient as a reflector. This is why there are colours on my monitor and in reality that I can’t reproduce with paint. I think the best use of paint to create a colour is to mix the colour on my pallet and paint it on the canvas. Glazes can certainly make fine adjustments but the best colour is a mix and apply. This is also why there are some colours that I just can’t get by mixing the paints I regularly use; I need a different pigment for that special colour and I often apply it as purely as I can without mixing in anything else; I’m sure this is why there are so many paint colours using different pigments.
Take a butterfly for example. The wing colours are created by the shape of the scales on its wings. They reflect only a very small frequency range. If you illuminate them with a sodium ark light for example the only frequency available to reflect is the yellow of the sodium ark. If the butterfly’s wings don’t reflect this frequency then I will see only a tint of the sodium colour or black. The butterfly’s wings are much more efficient than paint.
On a monitor this is easy to show. There are normally only three colours; red, green and blue. Add them together in equal amounts and you get white. With paint when you add a colour to white you are reducing the reflected spectrum on everything except the colour that you are adding; the result is slightly grey. It’s not just a lighter tint of the one added, it’s grey because of the inefficiency of paint.
So far the best results I’ve had with glazing are when I want to lighten an area or shift the colour slightly. Create a warmer look for example. Some artists get wonderful results with glazing. They add forty or more layers of glaze to get a wonderful colour. I don’t have the patience.