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 PBr7 Natural Iron Oxide.
Who makes it
PBr7 Natural Iron Oxide3
- Williamsburg Handmade Oil Colors No. 6001671PBr7LF I Semi-opaqueSeries 137 ml tube · 150 ml tube · 8 fl oz can* · 16 fl oz can*About Williamsburg
- Old Holland Classic Oil Colours No. A349PBr7LF 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
PBr6 Brown Iron Oxide1
- PBr6LF I TransparentSeries 140 ml tube · 60 ml tube* · 225 ml tube · 1000 ml can*About Michael Harding
Sizes are the ones each line is sold in; marks a size only some colors come in. Check the store for a particular color.