2 different recipes. Brands sell different pigment mixtures under this name, so they won't all look or mix alike. Compare the pigments below; the most common is PY40 Aureolin.
Who makes it
PY40 Aureolin5
- Grumbacher Pre-Tested Artists' Oil No. P003
- Holbein Artists' Oil Color No. H248
- PY40LF I TransparentSeries 540 ml tube · 60 ml tube* · 225 ml tube · 1000 ml can*About Michael Harding
- PY40LF II TransparentSeries 540 ml tube · 150 ml tube · 300 ml cartridge · 500 ml tin · 1000 ml tin* · 4000 ml tin*About Art Spectrum
- Blockx Extra-Fine Oil Colours No. 212913
PY150 Nickel Azo Yellow2
- Rembrandt Artists' Oil Colour No. 242PY150LF I Semi-transparentSeries 415 ml tube · 40 ml tube · 60 ml tube* · 150 ml tube*About Rembrandt
Sizes are the ones each line is sold in; marks a size only some colors come in. Check the store for a particular color.