Meet the Soil Scientists Using Dirt to Make Stunning Paints

In September, as wildfire raged in Medicine Bow National Forest, Karen Vaughan watched smoke billow in a choked-off Wyoming sky. The sun was reduced to a matte neon-pink disc behind the haze, and Vaughan worried about her research site in the burning mountains. One of her graduate students still had one more day of fieldwork to complete, and the roads would soon be closed, if they weren’t already. Vaughan’s family—her husband and two kids—were outside too, watching as a light gray layer of wind-blown ash settled onto the landscape. The ash and vivid colors sparked something in Vaughan, who continually sought new inspiration for the paint she makes. She began dashing around, scraping the sediment from every flat surface and encouraging her kids to help collect the fine powder. She decided to incorporate that ash into watercolor pigments with hues reflecting the fire, indelibly preserving the moment. The small batch of paints, distributed to friends and local artists, would be used to create depictions of the destructive forces that allowed their creation in the first place. “You’re breathing that air, even in your house, and you look outside and see that weird orange glow,” says Vaughan. “You couldn’t help but be a part of that.”

A soil scientist and a professor at the University of Wyoming, Vaughan sees a lot more soils than the average person, and certainly knows them more intimately. Over many years spent examining them, she has come to appreciate their natural beauty and immense variability. Two years ago, she began channeling that appreciation into a product she could share with the world, turning the soils she loved into watercolor pigments. Now, she and her collaborator, Yamina Pressler, a soil scientist at California Polytechnic University, use soils to make pigments and paintings, bridging the gap between science and art. By sharing both their creative processes and scientific knowledge on social media and connecting with artists, scientists and the public, they aim to make soil education entertaining.

Vaughan’s research is in pedology, which means she studies minute, subtle changes within a soil. Does the size of the grains change? Do the colors fade into each other or get cut off abruptly? What microorganisms are present at different levels in the soil? The very nature of her field, she says, is subjective. “It is an art form,” she says. “It takes a nuanced eye to really be able to see the changes within a soil.”

Her job requires her to hop in a deep hole, map out tiny changes few people notice and interpret the soil’s history. Her specialty is studying water in soils: How much is there? When is it present? How does it change the soil’s chemistry? What features does it leave behind? Her work helps us understand how soils form in unique environments, like wetlands in the otherwise arid Wyoming mountains, and how fragile soils like permafrost might respond to climate change.

To the uninitiated, the landscape of Wyoming might seem like a monotonous stretch of tan dirt. But that idea is exactly what Vauhgan is trying to change through her art. By explaining to artists and curious laypeople how the myriad hues in soils come to be and sharing them visually through both her own creative works and those by other artists, she hopes to give people the ability to see soil as more than “just dirt.”

“Sometimes art opens the door to people wanting to learn about science,” says Laura Guertin, a geology professor at Pennsylvania State—Brandywine. Guertin too has brought art into science, both for her classrooms and her communities, by crocheting temperature records and quilting climate change stories. “Using different perspectives to introduce a topic, like soil, can help people understand and connect with it a little more.”

Soil is often overlooked in basic geology classes, says Guertin, and understanding how it works and where it comes from is important. “Without soil, you don’t have the rest of Earth’s systems,” she says. “It’s such a fundamental material, it’s the basis of our food systems.” And society’s indifference to soil led to the Dust Bowl, one of the greatest environmental disasters in the history of the United States. “With my students, I talk about the Dust Bowl and how it was a loss of soil that triggered a chain reaction, impacting a broad cross-section of society,” says Guertin.

Vaughan began making pigments as a fun way to engage with her kids, now ages 7 and 9, and keep them away from screens. They come soil collecting with her, and occasionally help mix the pigments and paint. But the main reason she makes pigments now is to share her perspective on soils’ inherent beauty with the public. “I found all these amazing soil colors,” Vaughan says, “and I wanted to do something more with them. I wanted them to persist longer.”

She recognized that by making paints she could share science with people who lack her expert training. “Spending all that time as a pedologist looking at soil formation and thinking about how much the colors of the soil can tell us about the natural history of that area, I wanted to let people in, open their eyes a little bit,” she says.

Vaughan collects soils for pigments almost everywhere she goes, from dirt collected in a wetland study site high in the mountains to coal unearthed in her backyard. On a family road trip to Florida in a campervan, for instance, she grabbed a small bag of soil from every stop, with the intent of creating a palette that reflects that memory. One dull pandemic day, she and her kids took to their bikes on a scavenger hunt near her home for as many colors of the rainbow that they could find. It was a change of pace for Vaughan, who is normally more opportunistic than intentional in her soil collecting. She made a palette of red, brown, orange, white, yellow and purple to represent that effort. And, of course, she has the three-hue palette from the September wildfire, corners of which were still smoldering away when we spoke in November.

Because it was just a small batch, Vaughan distributed the ash-infused pigments to local artists and a few select clients to create works reflecting the wildfires. California artist Tina Pressler, Yamina’s mother, painted a patchwork American bison, the West’s once-ubiquitous megafauna, and Bethann Merkle, a Wyoming artist and science communicator, created a series of three abstract paintings of fire-wrought forest textures. The ash-infused pigments felt fluid and heavy, says Tina. “The addition of ash made it seem really tactile, in a way, and I loved it.”

“I’ve long had a fondness for rocks—my windowsills are piled up with them at home and at work—but [Vaughan’s] work and pigments have helped me expand that curiosity and appreciation to the soil,” says Merkle.

Before Vaughan began sharing her pigments with artists, she had to spend some time getting the day-long pigment-making process down. It took her a few tries: “My first pigments,” she says with a laugh, “were chunky and terrible. But I gave them away with a disclaimer.”

In the first step of her process, Vaughan removes the sandy portions of the soil, leaving only fine silts and clays mixed in water, which she then pours into a cookie sheet and bakes in the oven for a few hours. After all the water has evaporated, the soil appears cracked and desiccated, like a mudflat after a long summer drought. “Look, mom, it’s all wrinkly like you,” her daughter once helpfully said. Vaughan grinds the baked silt into a fine, homogenous powder. Then comes Vaughan’s most meditative step: mulling, or combining the soil with the watercolor medium— a mixture of water, gum arabic, honey and vegetable glycerin. Only then does she get a sense for what the final hue will be. “You might start with an amazing green soil that, all of a sudden, becomes this dull, greenish white. And that’s okay,” Vaughan says. “It’s always a color I’ve never made before, so I’m thrilled.”

The colors of the paint come straight from the soil’s geologic past: Bright reds and oranges mean the soils were exposed to the oxidizing effects of intense climates, long stretches of time or both. Dark browns and blacks represent rich organic matter, reflecting the cycle of life and death at the Earth’s surface. Brighter hues result from minerals with specific elements; the presence of copper lends minerals blue-green colors, sulfur creates vibrant yellows and manganese presents as faded purple. Stark whites could mean acid once trickled down through the soil from a pine copse, or that ash once settled over the landscape, like that which Vaughan collected in September.

“Everything has a story,” Guertin says. “What’s been here in the past? Where do these colors come from? Where do these materials come from that give us these colors? I love that [Vaughan is] taking the soil science and showing how you can break it down to materials, to these pigments that have cultural meaning and to painting, which people already have a familiarity with.”

Vaughan describes her soil collecting, her artistic process and the science of each soil on Instagram, where she answers questions about chemistry, location and geology. Sometimes artists send in questions about the science of pigment-making itself, but many are just interested in learning more about the natural world. Depending on how much detail people want, she’ll even send along some scientific papers in a private message. Because so many of her clients are interested in learning about the soils, Vaughan is planning to start including a “soil story” with each palette shipped out.

Vaughan’s connections with artists sometimes grow from the virtual world to working together in person. Diana Baumbach, a Wyoming artist who Vaughan collaborated with a few years ago, loved going into the field with the scientist to forage for natural materials, including soil. “I really hadn’t thought about soil or considered it as a material before,” Baumbach said. “Looking at soil profiles with [Vaughan] was totally new for me. We both pulled each other into our worlds, which I thought were quite different. In the end, it was surprising how many intersections there actually were between my work and her work.”

While Vaughan does paint with her pigments, she doesn’t typically share her work; she leaves that to the younger Pressler, for whom painting has become a public affair. Growing up with an artist mother, Pressler says, meant that art was always in the background. “But it wasn’t until I started painting soils that I began to embody being an artist as part of my identity.”

Pressler also connects with an interested audience through social media. She hosts live paint-along sessions in her ‘virtual soil art studio’ on Instagram, inviting participants of all backgrounds to create soil-focused art inspired by where they live. These two-hour public sessions are open to children and adults, scientists and laypeople.

Tatiana Prestininzi, who has a bachelor’s in agricultural science but never cared much for soil science, now brings her young niece and nephew to Pressler’s paint-along sessions. “It’s not only from the artistic side, but we’re also getting the educational side of things,” she says. “It’s not just the 15-to-30-somethings on Instagram, she’s got 7 and 5-year-olds learning about soil profiles… so now I can go hike around San Diego with my eight-year-old niece and have a conversation about the soils she sees. She’ll ask to paint it and send it to the ‘soil doctor.’”

Through Vaughan’s art outreach and Pressler’s educational outreach, the scientists aim to inspire in the public the feelings children have while digging in the dirt and wondering at the world around them. Vaughan’s process of finding soils for pigments has a sense of play that is really infectious, says Baumbach. And while Pressler does draw soils realistically, she’s more drawn to whimsical doodles that reflect her feelings towards soil, which she shares on her Instagram sessions, along with the science stories behind them.

Tapping into her artistic side has helped Vaughan re-imagine what college soil science classes can be. She has her students sketch frequently, and she occasionally has them paint with soils. Her collaboration with Baumbach led the pair to cross-pollinate art and science further, with Baumbach bringing her art students to Vaughan’s science labs to talk about color and Vaughan giving guest lectures in Baumbach’s art materials courses. “Really, basic things like observation and analysis are at the core of what we both do, and we’re communicating through materials and visual forms,” Baumbach says. “The students are just starting to think broadly about materials, so hearing Karen talk about soils as a raw material is really interesting for them.”

In addition to giving talks about soil science and life as a researcher at K-12 schools and museums, Pressler works directly with teachers, taking them into the field and lab so they can get firsthand experience with soils. “They can then go back to their students and talk about soils and ecology, and the process of science, from their perspective,” says Pressler. “It’s more meaningful to the students that way.”

Michelle Bartholomew, a middle- and high-school science teacher, jumped at the chance to head into the field with Pressler in Colorado and Alaska. They developed soil science classes together, did some drawing and studied soils. “That was the highlight of my time with her, working on those tundra soils,” Bartholomew says. “It’s doing science, you know? Even though we’re science teachers, we don’t get to do that. It rejuvenated me… and gave me new ways of teaching old concepts.”

Pressler and Vaughan also believe in the importance of being role models who break out of the compartmentalization so common in science today. “It’s about showing young people that there are lots of different ways to be a scientist,” Pressler says, “that you can be colorful and explore different parts of your curiosity and still be a scientist.”

“We used to be Renaissance people,” Vaughan says. “Now it’s, ‘You need to stay in your box so you can do well at that.’ I feel like we’ve almost made it okay to be artistic while also being a scientist.”