Chemist and inventor Kevin A. McIntyre set out to develop a cheaper way to replicate iron gall printing, which combines iron and tannic acids to create a permanent, waterproof pigment that starts off bold and darkens with age. Iron gall was the dominant ink chemistry in Europe from the 5th to 19th centuries but fell out of favor as options that were less corrosive to paper emerged. Antiquarians and historical reproduction artists still use iron gall to mimic the aesthetics and colors of that 1,400 period, but it can be expensive and incompatible with modern printing methods. McIntyre’s approach expands iron gall into inkjet and 3D printing, as well as other delivery methods, like the Prussian blue formulation coating clay balls and other objects in the photos above, mimicking the slow deepening of the retro ink. But it turns out the material absorbs CO2 out of the air as it darkens. “While originally developed as a novel printing solution,” McIntyre says, “My technology creates a unique tannin-mineral surface that acts as a passive CO2 collector.” —Craig Bettenhausen
A color developed by Egyptians thousands of years ago has a modern-day application as well – the pigment can boost energy efficiency by cooling rooftops and walls, and could also enable solar generation of electricity via windows.
Egyptian blue, derived from calcium copper silicate, was routinely used on ancient depictions of gods and royalty. Previous studies have shown that when Egyptian blue absorbs visible light, it then emits light in the near-infrared range. Now a team led by researchers at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) has confirmed the pigment’s fluorescence can be 10 times stronger than previously thought.
Measuring the temperature of surfaces coated in Egyptian blue and related compounds while they are exposed to sunlight, Berkeley Lab researchers found the fluorescent blues can emit nearly 100 percent as many photons as they absorb. The energy efficiency of the emission process is up to 70 percent (the infrared photons carry less energy than visible photons).
Often, the findings of fundamental scientific research are many steps away from a product that can be immediately brought to the public. But every once in a while, opportunity makes an early appearance.
Such was the case for a team from the Department of Energy’s Joint BioEnergy Institute (JBEI), whose outside-the-box thinking when investigating microbe-based biomanufacturing led straight to an eco-friendly production platform for a blue pigment called indigoidine. With a similar vividly saturated hue as synthetic indigo, a dye used around the world to color denim and many other items, the team’s fungi-produced indigoidine could provide an alternative to a largely environmentally unfriendly process.
“Originally extracted from plants, most indigo used today is synthesized,” said lead researcher Aindrila Mukhopadhyay, who directs the Host Engineering team at JBEI. “These processes are efficient and inexpensive, but they often require toxic chemicals and generate a lot of dangerous waste. With our work we now have a way to efficiently produce a blue pigment that uses inexpensive, sustainable carbon sources instead of harsh precursors. And so far, the platform checks many of the boxes in its promise to be scaled-up for commercial markets.”
