Sprayable safety: Stanford engineers wildfire-shielding gel to protect homes

As the planet warms and droughts intensify, wildfires are becoming increasingly frequent and devastating. In recent years, these uncontrollable blazes have destroyed countless homes, taken lives, and wreaked havoc on economies.

To address this growing crisis, researchers at Stanford University have engineered a revolutionary water-enhancing gel that could significantly improve our ability to protect homes and critical infrastructure from the ravages of wildfires.

Their findings suggest that this new gel far surpasses existing commercial solutions in both longevity and effectiveness.

A revolutionary defense against wildfires

Wildfires thrive in hot, dry environments, and traditional fire-fighting methods often struggle to keep up. The problem with current water-enhancing gels is that they dry out quickly—typically within 45 minutes under standard wildfire conditions—rendering them ineffective just when they are needed most.

Explaining the limitations of these gels, Eric Appel, an associate professor of materials science and engineering at Stanford and the senior author of the study, stated, “Under typical wildfire conditions, current water-enhancing gels dry out in 45 minutes. We’ve developed a gel that would have a broader application window—you can spray it further in advance of the fire and still get the benefit of the protection—and it will work better when the fire comes.”

The Stanford team’s breakthrough gel is designed to be more versatile and longer-lasting. Unlike traditional gels , which rely solely on water to create a protective barrier, this new formulation introduces a multi-layered defense mechanism.

The gel is composed of a cellulose-based polymer combined with silica particles. When subjected to the intense heat of a wildfire , the water in the gel evaporates, and the cellulose burns away. What remains is a silica-based aerogel—a lightweight, porous material known for its excellent insulation properties.

Highlighting the significance of this discovery, Changxin “Lyla” Dong, the lead author of the study, said in the press release, “We have discovered a unique phenomenon where a soft, squishy hydrogel seamlessly transitions into a robust aerogel shield under heat, offering enhanced and long-lasting wildfire protection. This environmentally conscious breakthrough surpasses current commercial solutions, offering a superior and scalable defense against wildfires.”

The science behind the gel

The transformation from hydrogel to aerogel is what makes this new material so effective. Once the water and cellulose components are gone, the remaining silica particles form a foam-like structure that acts as a thermal insulator.

“When the water boils off and all of the cellulose burns off, we’re left with the silica particles assembled into a foam,” Appel elaborates. “That foam is highly insulative and ends up scattering all of the heat, completely protecting the substrate underneath it.”

This silica aerogel, which has been used in space exploration due to its lightweight and heat-resistant properties, provides a powerful shield against wildfire-induced heat. The researchers tested various formulations of their gel by applying it to plywood and exposing it to direct flames from a gas hand torch, which burns at much higher temperatures than typical wildfires.

Their most effective gel formulation provided protection for over seven minutes before the plywood began to char. In comparison, a commercially available water-enhancing gel lasted less than 90 seconds under the same conditions.

“Traditional gels don’t work once they dry out,” Appel pointed out. “Our materials form this silica aerogel when exposed to fire that continues to protect the treated substrates after all the water has evaporated. These materials can be easily washed away once the fire is gone.”

From serendipity to a lifesaving innovation

The journey to this groundbreaking discovery was marked by a mix of scientific curiosity and serendipity. Appel and his team have been working on wildfire prevention technologies for years.

In 2019, they developed a similar gel designed to hold fire retardants on vegetation for extended periods, aiming to prevent wildfires in vulnerable areas. However, their latest discovery was somewhat unexpected.

“We’ve been working with this platform for years now,” Appel recalled in the press release. “This new development was somewhat serendipitous—we were wondering how these gels would behave on their own, so we just smushed some on a piece of wood and exposed it to flames from a torch we had laying around the lab. What we observed was this super cool outcome where the gels puffed up into an aerogel foam.”

Following this accidental discovery, the team spent several more years refining the gel’s formulation. Today, it is stable during storage, easy to spray using standard equipment, and adheres well to a wide range of surfaces.

The gel is also environmentally friendly and composed of non-toxic materials that are already approved for use by the U.S. Forest Service. The researchers conducted additional studies to confirm that the gel breaks down easily in the soil, posing no long-term environmental risks.

“They’re safe for both people and the environment,” Appel assured. “There may need to be additional optimization, but my hope is that we can do pilot-scale application and evaluation of these gels so we can use them to help protect critical infrastructure when a fire comes through.”

The research was published in the journal Advanced Materials .