Hi, Patrick,

Indanthrone Blue (PB 60) is indeed desaturated. So, I would believe you can’t use it on its own to replace Ultramarine Blue (PB 29) entirely. However, I don’t know exactly how you work.

Of course, getting the values right is always more important. So even if your blue is desaturated, you should still be able to get something very nice if you get all the values accurately. So I think you should do what you feel the most comfortable with.

I love indanthrone blue and have been using it as my main blue for several years. I created a limited palette out of it, plus its cousin anthraquinone red (PR177), azo yellow (PY150), benzimidazolone orange (PO62), raw umber, and yellow ochre, plus the two whites. I can make pretty much anything with these.

I recently switched mediums from acrylics and used oils and now homemade casein. In both I started out with ultramarine blue but switched quickly back to indanthrone blue. After all this time, ultramarine blue just looks insipid in comparison. And yes, indanthrone blue en masse is almost black and with raw umber makes wonderful black and with orange can create wonderful greys for clouds. I find it’s an excellent sky color or for water, and it’s good thinned to make shadows and modeling. It just has great character.

Contrary to accepted wisdom, I suggest Anthraquinone Blue (or Indanthrone) isn’t necessarily as desaturated as all that.

In my experience, in watercolor tube paint, Indanthrone can be rather well saturated, depending on the brand. Handprint.com does confirm what others (above) have already stated, that the pigment PB60 (Indanthrone or Indanthren or Indanthrene or Anthraquinone Blue) is less saturated than PB29 (Ultramarine Blue). And I don’t disagree, pigment per pigment, PB60 is probably less saturated than PB29, yup, no need to question that.

But my personal tube of PB60, Daniel Smith Indanthrone Blue, is EXTREMELY highly saturated and produces a very dark deep rich color. Plus, the pigment PB60 doesn’t granulate the same way that PB29 does (as we are all familiar, I’m sure) which actually means it’s a bit more free to remain deeper and darker. It doesn’t clump together into smaller granules like PB29; consequently, at any given point, the PB60 is 100% of itself, rather than either a clump of itself or a paler gap between clumps.

It’s just an eye thing. Can’t claim it’s scientific. When I paint the two next to each other, I can see what the scientists would mean to indicate, by the fact that PB29 is more saturated than PB60; but I also see what looks like the ultimate effect of one brand name (Daniel Smith) overwhelming the general scientific theory with a specific result in practice, by which PB60 actually looks darker than some PB29s.

Also, “darker” and “more intense” are really not synonyms for one another. So I’m not entirely sure that I’ve expressed myself as clearly as I might have done. Eh … Might try to post pics, if I can get to a scanner or camera later …

Hi, Patrick – I love the stuff.
Clifton – I sat there wondering how indanthrone blue could be considered to have less intensity than ultramarine, but your connection of it to granulation makes a lot of sense to me.

Oh Great — thanks, now I have to try it.

Indanthrone Blue looks like a beautiful night ski color.

Seems like I remember one of the major US oil paint companies trying to discontinue it, only to have customers ask for it to stay. Small, but loyal following.

Also, I just love pronouncing the word “in DAN throne.” It sounds like a Mardi Gras parade … or the bad guy in a James Bond movie.

Both ultramarine and anthraquinone are transparent if that matters.