I find I rarely need to use a cool, or green-biased yellow as I am rarely mixing the very bright greens it can make. For me, a good mid yellow that is neither cool nor warm i.e. neither orange-biased nor green-biased is a more useful option than the traditional cadmium or hansa yellow light. This works very well as the only yellow in a limited palette, but is also a nice building colour for an expanded palette.
Aureolin PY40 was the traditional mid-yellow choice, but is not recommended as it goes brown or grey or fades. Originally recommended as a watercolour, now known to be best avoided entirely.
So in my search for a better alternative I have tried a number of other yellows and my favourite is Hansa Yellow Medium by Daniel Smith. Other great choices are Daniel Smith's Quinaphthalone Yellow, Schmincke's Pure Yellow or M.Graham's Azo Yellow for a studio colour since it never really dries due to the honey mixed into the paint. As far as I can work out, all of these are ASTM II pigments, which is acceptable for watercolour. Cadmium yellows are ASTM I but opaque.
Here is my mid-yellows page.
|Moleskine Watercolour Sketchbook showing mid yellows including Aureolin (fugitive), Cadmium Yellows and Hansa Yellow Medium.|
Watercolour Comparisons 2 - mid yellows here
Watercolour Comparisons 3 - Primary Red here
Watercolour Comparisons 4 - Burnt Sienna here
Watercolour Comparisons 5 - Greens (Single Pigment, convenience mixes and special effect) here
Watercolour Comparisons 6 - Reds (Cool, mid and warm) here
Watercolour Comparisons 7 - Yellows (cool mid and warm) here
Watercolour Comparisons 8 - Blues here