Why not to use white in watercolor?
Nicola Blakemore 
The simple answer is that it will make your watercolour paint colour opaque Watercolour paints are admired for their transluscence.
It is often said that when painting with watercolour white is never used.
That is often because the white of the paper is used instead. However adding white can really change the effect you may want. Imagine what you are painting and the effect you want to create.
I hope this short video helps.
Categories: : All about paint