The metal tubes of paint glistened subtly under the fluorescent lights in the paint aisle, with each uniform tube neatly hung in a row. I scanned through the titles, like Hansa Yellow Deep, then Transparent Orange, and turned over each one of the vaguely named tubes of yellowish-orange paints to look for the pigment information on the back. I was on a mission to find one pigment in particular, PO62. The tube marked Permanent Orange looked promising. Finally, there it was, a single-pingment Benzimidazolone Orange-- the only one in the store. PO62 can be a bit hard to find as only a handful of brands offer it as a stand-alone pigment.

Back in the studio, I poured a pumpkin orange daub of this novel color onto the worn, greyed surface of a palette I'd had since my student days at RISD. The surface was rough with years of scraping down, cleaning, and adding new paint. On the grey palette the Benzimidazolone shone brightly. However, when set next to the finest-quality cadmium oranges, of which I'd grown quite fond, this orange had an odd note of desaturation to it. Taken in isolation, Benzimidazolone Orange looks incredibly bright, but set in an arpeggio of cadmiums, it looked a bit duller.

I soon began to quite enjoy this newcomer to the palette. While it would be nice to have even better lightfastness, for a synthetic organic orange, 7 out of 8 on the Blue Wool Scale is pretty good.

Perhaps the most common question about Benzimidazolone Orange is whether it can truly replace Cadmium Orange. We'll talk about it's features, its tints, and the million dollar question about cadmiums, and explore how it compares to the other oranges in the paintbox.

Benzimidazolone Orange H5G, is labeled PO62 for short. An orange pigment, sometimes described as middle-value yellow to middle orange which is somewhere between semi-transparent and semi-opaque. It is often suggested as an alternative to cadmium orange, but PO62 does not have the same covering power, especially when used thinly. It is a lovely color on its own though, and so we'd suggest different uses for the two pigments.

Some sources, such as Mayer, describe it as transparent, which is interesting, as we have encountered it as semi-transparent. Whether this is due to paint formulation recipes or additives makes one wonder. At first we wondered if his notes may refer more to something like PO60 (a discontinued Benzimidazolone Orange) than PO62, but he has separate entries for both pigments.

The bit of radiance in thin applications can be detected in the picture here. Where a high quality cadmium orange has incredible opacity and coverage, the tendency to want to glaze can be found in PO62. If a person is looking for a single-pigment orange with touch more transparency, PO62 may be a good choice.

Compared with genuine Cadmium Orange, PO62 is less chromatic, less lightfast, and less opaque, but some versions may have good weatherfastness.

In terms of the highest chroma colors possible in oil paint, Benzimidazolone Orange falls slightly short of high quality cadmiums.

It turns out that Cadmium Orange, PO20, is actually a difficult pigment to replace. If a person is absolutely unable to use cadmiums, Benzimidazolone Orange could be a good option, however Benzimidazolone Orange PO62 is not as non-toxic as people think. (More on this in the section on toxicity).

In terms of painterly qualities, PO62 is slightly less opaque than Cadmium Orange, PO20, however, Benzimidazolone Orange is a little easier to coax into a glaze when used thinly.

Our main issue when it comes to replacement is the slight loss of chroma in PO62 as well as slightly less lightfastness.

In general in oil paints, the long-term fate of impasto work can be a bit iffy, but Benzimidazolone Orange seems as good as any color for this kind of work. The way the Gamblin version is formulated, the color has plenty of body and is fairly opaque, but shows a bit of glow in thin layers.

This particular rendition of PO62 happened to be an orange that leans yellow. Apparently it can also be found sometimes in a redder-orange edition, but the yellower-orange seems to be fairly common.

Just as a heads up, there is another Benzimidazolone Orange (PO60) which is different from PO62 and has different properties. Sometimes PO60 gets mentioned for its transparency, and given the similar names, the two can become conflated. Unfortunately PO60 has been discontinued, but we still have PO62.

Previously thought to be in the category of Low Concern, new research suggests that there may be more concern warranted for Benzimidazolone Orange than was given to it in the past, as it is generally labeled as non-toxic.

We are grateful for Monona Rossol's work on pigments and hazards for artits, as there are currently gaps in the way that emerging research is disseminated to artists as well as areas where more research needs to be done. Specifically, Rossol highlights the lack of data surrounding PO62 and suggests that there may be concern from a chemical standpoint in regard to how it would metabolize. We are not toicologists, so please consult the relevant experts.

Rossol's work highlights that PO62 may be a mutagen and could also metabolize to cause a serious health condition called methemoglobinemia. Reference Monona Rossol's research available upon request here for more information.

As with all pigments, do not breathe the dust.

In regard to all art supplies, even ones labeled non-toxic, please treat all pigments and paints with proper studio safety protocols.