PR101 and PR102 (Pigment Red 101 and 102) are among my favorite pigments for paint and they come in a large variety of colors. PR102 is a natural red iron oxide (red ochre) and PR101 is the synthetic version. Below is my collection of oil paints using either of these as a single pigment paint with nothing else added. I photographed this in direct sunlight during the afternoon. All of the paints were mixed twice with about an equal 50/50 mix with white.
Old Holland Yellow Ochre Burnt
This is my only natural red ochre in oil paint. As I understand it this pigment is made by roasting natural yellow ochre pigment until it turns reddish. It could make a good alternative to burnt sienna. It’s a little lighter and brighter, and has a stronger color.
Winsor & Newton Transparent Red Ochre
I wasn’t really sure what to expect when I got this because the name sounds like it’d be what’s normally called Transparent Red Oxide, which is the variety of PR101 that W&N already uses in their “Burnt Sienna”, but this is really very different. I think it’s close to the same as the Yellow Ochre Burnt above it but this is a slightly cleaner and more pure color. As the name suggests, this paint is semi transparent. The tinting strength isn’t as overpowering as some of the others in this list so it’s a bit easier to work with. This is one of those paints that I wish I had gotten years ago. It might even be my favorite red ochre.
Rembrandt Burnt Sienna
Although real Burnt Sienna is made from either PBr6 or PBr7, there are a few brands of paint that use a Transparent Red Oxide version of PR101 instead, which has a much stronger color, higher transparency, and higher tinting strength than actual burnt sienna. It doesn’t show up well in the photo but this particular one is lighter in masstone than the “burnt sienna” below it from W&N.
Winsor & Newton Burnt Sienna
A nice example of Transparent Red Oxide. It has good transparency. I tend to prefer paints like this over actual burnt sienna for the greater color strength.
Blue Ridge Transparent Red Oxide
Very similar to the above paint, but not as transparent. This one also seems to have a slightly higher tinting strength, but I can’t guarantee that I got the mix with white an exact 50/50 mix on any of these.
Old Holland English Red
Now we’re getting into the slightly cooler temperature colors for red ochres. This is a very high tinting strength paint, and easily overpowers most other paints that I mix it with unless I use extremely small amounts of this. Because of that, I don’t think I’ll ever run out of this one when you consider how little of it is needed in each paint mix. This one it so similar to the venetian red below that I actually mixed up the labels on the image at first. I’m 99% sure I have it right now since I kept the tubes lined up in the same order that I placed the paint on the palette and because this paint has a thicker, more viscous consistency.
Winsor & Newton Venetian Red
There’s a little bit of variety of colors that are referred to by different brands as “venetian red” but this name is generally given to a semi-cool earth red that’s not as cool as something like an Indian Red.
Blockx Mars Violet
As far as I know this is about as cool as red ochres can get. I bought this one from Blockx because when I looked at a paint chart someone else had made of different brands of mars violet the one from Blockx looked like the coolest. On an earth palette of red and yellow ochres this could be a very useful.
A similar comparison of yellow ochre oil paints can be found here.