Intense brightness. Incredible color strength. Maximum opacity. And clean mixing. Cadmium pigments bring something special to the artist's palette: a spectrum of reds, oranges and yellows that pack a punch.

Cadmium is a soft heavy metal, a little like mercury and zinc. Its compounds are used as red, orange and yellow pigments, and have been since the 1840s.

Concerns about the safety of this pigment have been bubbling for years. Until recently, cadmium hue colors were the only option for artists wanting to avoid the heavy metal pigment. These give results in the same ballpark, but a pale imitation of the real thing, lacking in strength, vibrancy and overall performance. While the level of soluble cadmium used in paints doesn't pose a significant risk to artists, there are concerns about its environmental impact. There's been discussion about banning cadmium from the art world but no universal view.

In 2014, Liquitex started to look for a better solution. They set out to make the world's first cadmium-free acrylic paint with the same performance, vibrancy and lightfastness as cadmium paint. But how do you make an acrylic behave like a cadmium color without any actual cadmium? Fans of cadmium said it couldn't be done. But their chemists like a challenge.

New pigment advances unlocked the answer. The Liquitex lab team used a range of developments in organic and inorganic pigment technology. It was a meticulous three-year process, making use of the very specific optical and mixing qualities of a spectrum of pigments. Their process: Combine. Test. Adjust. Repeat.

What does it take to make a cadmium-free acrylic with the same characteristics of a cadmium, but without the risks? The team developed an identical cadmium-free match, but before they were satisfied with the results, they put the new formula through a final round of lab tests. These included:

• Archival lightfastness measurements
• Color mass tone checks for brightness and overall match
• Viscosity and rheology tests to see how it handled
• Color reduction evaluation — 10:1 with titanium white to compare color strength and shade when mixed
• Specific gravity checks to test weight and opacity

Liquitex cut out the cadmium and their tests demonstrated they could keep the identical much-loved character. So they challenged their artists to spot the difference. Prioritizing the involvement of the art community in all of their efforts, they gave out thousands of free blind test sets. After a month of using the two tubes — one cadmium color, one cadmium-free — the results spoke for themselves. The colors were so hard to tell apart that artists actually argued over which was which.

Available in Heavy Body, Soft Body and Acrylic Gouache, the Liquitex cadmium-free range is made up of three reds, one orange and three yellows. Each gives matched visual and physical performance without the health or environmental concerns of cadmium. You can find the cadmium-free alternative easily by looking out for the bottle and tube labels with green type. With or without? It's your choice.