Isoindoline Yellow – PY139
Isoindoline pigments are a group of modern dyes with shades from red to green-yellow, of which only the warm yellow PY139 is fairly common in watercolor. isoindoline yellow has an orange-yellow hue, is a semi-transparent, staining and very intense pigment. In full tone you can probably say that it is orange, while diluted has a beautiful medium yellow tone.
The color is not at all suitable for mixtures in the green direction if you strive for a reasonably clear mixture, green colors mixed with isoindoline yellow and some blue color all become very cloudy. The color is much better suited to mixtures with different red and other yellow colors but it is beautiful as it is, unmixed.
The pigment was invented in 1964 but only began to be used as an artist’s pigment several years later. It is not common as a watercolor paint, I have only found two, of the larger manufacturers, that have the paint: MaimeriBlu and Daniel Smith. MaimeriBlu has the bad taste to call the color gamboge (several years ago they gave the name indian yellow to the same color!) While DS uses the real name Isoindoline Yellow. In addition to these, the pigment is present as part of several different color mixtures at different manufacturers.
MaimeriBlu – Gamboge (Hue) – PY139
Daniel Smith – Isoindoline Yellow – PY139
Color index name: PY139