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 PY42 Yellow Iron Oxide.
Who makes it
PY42 Yellow Iron Oxide3
- Old Holland Classic Oil Colours No. A319PY42LF ISeries A18 ml tube* · 40 ml tube · 60 ml tube* · 125 ml tube · 225 ml tube · 475 ml tin* · 1000 ml tin*About Old Holland
- Blockx Extra-Fine Oil Colours No. 212311
PBr11 Magnesium Ferrite Brown1
- Holbein Artists' Oil Color No. H349
Sizes are the ones each line is sold in; marks a size only some colors come in. Check the store for a particular color.