PY159 is a granulating, low-strength primary yellow. It’s available as Winsor & Newton Lemon Yellow Deep (shown here), or as Schmincke’s Volcano Yellow (from the Supergranulating line).
Experiment Results
Gradient: Slighlty dull granulating mid-yellow in masstone, pale yellow otherwise. Very difficult to get a masstone and doesn’t grade easily. Does not rewet easily.
Opacity: Semi-transparent… or maybe just weak?
Color Mixes: Very difficult to mix because it is so weak compared to other colors. Mostly the colors just turned into slightly paler, granulating versions of themselves.
What Others Say
Winsor & Newton lemon yellow deep is the only source of this pigment in commercial watercolor paints. It is a pale, muted yellow, with an intrinsic whiteness similar to nickel titanate (PY53), which it apparently replaces in the brand color range.
Bruce MacEvoy, handprint.com
In discussing what W&N colors she chose to add to her palette, Kim Crick had this to say:
I also did not pick Lemon Yellow Deep PY159, despite it being rare. I felt that it wasn’t unique enough of a color to justify using it for the sake of it only being available from W&N. It is less transparent and weaker than other light yellow alternatives and has a dull mid tone similar to very diluted PY150 Transparent Yellow/Nickel Azo. Because PY175 or PY35 work so well for a bright lemon yellow, I had no real reason to add PY159 to my palette.
Kim Crick, Winsor & Newton Review
My Overall Review
I can see how this could be useful as a special effects color for a granulating, slightly yellow sheen – sunset clouds spring to mind – but in general it is too weak for me to find useful.
On my palette? Giving this one a miss.
Alternatives I Prefer: My granulating yellow of choice is Winsor Yellow (PY154), which is not listed as granulating but I found that it was – or at least, it seemed to make all the mixes more textured. Various yellow ochres could also work if you need a granulating, earthy yellow tone.
Schmincke sells the same pigment as Volcano Yellow in their super granulating line – one of only two single-pigment paints in that line if I remember right. I haven’t found a great use for it yet myself but it’s part of the mix for most if not all of the paints in the Desert & Shire sets.
You are so right! I’ve updated the text of my post to reflect this information.