Sometimes, you need the highest value highlight that it is possible to get in paint. Other times, you need a dark accent that is as low in value as you can get. Beecause paint doesn’t have anything like the dynamic range of human vision, it’s good in realistic painting to have as wide as range as you can. Small differences can sometimes be important.
The whitest white I’ve been able to find is “radiant white” by Gamblin. It’s titanium white in poppy oil. Most of the time I prefer paints ground in linseed or walnut, but for this purpose it makes sense to use the whitest possible pigment and the most colorless binder available. I’m still painting out test strips on a neutral gray background, but I’d guess it’s a quarter Munsell value step than the next brightest titanium white I’ve played with. I’ll use it only when I need a very light highlight.
The darkest black I have is Williamsburg intense black. The pigment is listed as “carbon from gas flame.” The back label says: “warning: very slow drying.” It is just noticeably darker than bone (“ivory”) black. The slow drying can be compensated for somewhat with a drier such as lead napthenate. I will use it only for dark accents at the very last stage of painting, so drying time for this particular paint is not that important for me.
2 May 2009:_ There’s a small highlight that I had previously painted in Old Holland titanium white. It’s light reflected from the shiny metal part of a clothes hangar. In real life this highlight is very noticeable, but on the painting, surrounded by relatively light tones, it did not stand out at all. I recently painted it in using pure Gamblin radiant white. It is noticeably brighter than before—giving an effect that is much more like what I was trying to depict.