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No, it isn´t.
Many years ago, when I studied oil painting with Sebastian Capella, I learned that White and Black are not colors.
Let me explain:
Color has three dimensions, hue, value and croma.
Hue, as in the tone like red, yellow, blue, etc.;
Value, referring to the degree of light or dark on a scale between black and white;
And Croma, as in intensity or purity of the color.
White fits within the first dimension, it does have a name, so it qualifies as a hue, but it does not have any variation in value, nor in croma. White will always be the lightest on the value scale and there is no more than one intensity - white is white.
Any color, added to another one, will change that color´s hue. For example, if you add red to yellow you get orange, blue to yellow makes green, and so on.
White, added to any other color does not change that color´s hue, it will only affect its value and diminish its intensity.
I don´t use pure white when painting a white object, pure white is rarely found in nature, there is always a hint of another hue present. Shadows and reflected colors will show us the white object in a lovely variety of colors! It´s only our brain which reads them as white.