I use titanium white as the white color on my palette. Its opacity is particularly suited to my “neo-pointillist” style.
I like how titanium white holds its own in mixtures with other colors. It lends opacity in mixes with transparent colors like ultramarine blue and alizarin crimson. A little white can tone down a saturated color. White can also make mixed colors a little cooler, which can be either good or bad depending on the effect you want. (One trick for keeping a color warm while still lightening the shade is to use some yellow along with the white.)
Anywhere you see what appears to be white in my paintings, it’s almost always a mixture of titanium white with a little bit of some other color. For example, those white-looking spots in the skies of my landscape paintings are typically titanium white mixed with a tiny dab of ultramarine blue.
Below is an older painting where I used white mixtures in several areas.
“Rough Pasture”, 2005