The ideal palette consists entirely of single-pigment colors. Such an ideal palette provides artists with total control over values and tones. This is especially important for artists, like me, who use lead white.
These days, even high-end brands use titanium white in their multi-pigment colors. Old Holland, for example, uses a blend of titanium white, zinc white, and ultramarine blue in its King’s Blue.
If I use this King’s Blue with one of my lead-containing tones, the horrid titanium white overpowers the other colors. Worse, such a malformed color appears garish next to the other well-behaved values in the painting. Of course, I can control these unruly colors but why not just mix the thing myself?
The trend among paint manufacturers is toward ever more ‘designer’ colors. Artists must be alert and not assume their paints are single pigment. To pick on Old Holland again, their Naples yellow deep extra is made with a single pigment, PBr24-chrome antimony titanate. Well and good. However, Old Holland offers two other ‘Naples yellows.’ Naples yellow extra is made with a blend of three other pigments–titanium white, zinc white, and mars orange (what happened to the chrome antimony titanate?). To cap off this example, their Naples yellow reddish extra has yet again a different assortment of pigments: diarylide orange, titanium white, nickel titanium yellow, and zinc white.
Old Holland is notorious for offering multiple versions of similarly-named paints, and, as we see here, often with entirely different pigments. If a leading brand like Old Holland is doing this marketing sleight of hand, you can bet the other brands are doing it too.