New fire retardant gel developed that can remain effective for months

It could be used to pretreat areas at high risk of fire ignitions to make them fire resistant

long term gel fire resistant
Overhead time-course images of 3 m × 3 m unmowed (standing) grass plots that were untreated or treated with different coverage levels, dried, weathered, and allowed to dry again over time in the environment prior to burning. The normalized area burned over time demonstrates that CL2 (coverage level 2, or 2 gallons per 100 square feet) is sufficient to preclude spreading of the fire. Air tankers use the same unit of measurement, coverage level, to specify how much retardant will be dropped. Figure from the research.

A group of scientists and engineers have developed a new fire retarding chemical, actually a gel in this case, that they say can be effective for months after being applied to vegetation.

The millions of gallons of red fire retardant that air tankers drop every year is usually made from ammonium phosphate or its derivatives. It has  been called “long term fire retardant” because even after it dries, the chemical can interfere with the combustion process and may still retard the spread of  a vegetation fire to a limited degree. However research and experience in the field has shown some formulations can be toxic to fish.

Gels have been used by firefighters for several decades on structure fires occasionally on vegetation fires. The products can be more effective than plain water due to their ability to stick to a vertical surface or vegetation. Water can remain in the gel for an hour or more depending on the ambient temperature, wind, and humidity. GelTech Solutions recently received a contract from the Oregon Department of Forestry to supply a blue-colored version of FireIce HVB-Fx gel to be used in air tankers. The company says the product passed the U.S. Forest Service’s newly revised, more challenging requirements for wildland fire chemicals. But the safety data sheet for the product says, “Titanium dioxide [a component of the product] has been classified by IARC as a possible carcinogen to humans (Group 2B) through inhalation of particulate dust.”  The safety data sheet goes on to say, “This classification is based on inadequate evidence for carcinogenicity in humans, but sufficient evidence of carcinogenicity in animals (rats). It should be noted that recent studies have demonstrated that the rat may be particularly sensitive to high levels of toxicity dusts such as titanium dioxide. Epidemiology studies do not suggest an increased risk of cancer in humans from occupational exposure to titanium dioxide. The conclusions of several epidemiology studies on more than 20,000 TiO2 industry workers in Europe and the USA did not suggest a carcinogenic effect of TiO2 dust on the human lung.”

This is not the first time blue gel has been used in air tankers. The photo below was taken in the Black Hills of South Dakota August 15, 2006.

blue gel air tanker fire retardant
A single engine air tanker drops blue gel on a fire near Shep’s Canyon in the Black Hills of South Dakota August 15, 2006. Photo by Bill Gabbert.

The scientists who developed the new fire retarding gel that they claim has “persistent retention”qualities said their formulation is environmentally benign, nontoxic, and will “biodegrade at desired timescales.” After application, it will retain its ability to prevent fires throughout the peak fire season, even after weathering that would sweep away conventional fire retardants. The cellulose-based gel-like fluid stays on target vegetation through wind, rain and other environmental exposure, they said.

“This has the potential to make wildland firefighting much more proactive, rather than reactive,” said Eric Appel, the study’s senior author and an assistant professor of materials science and engineering.

Treating wildfire prone areas prophylactically could provide a highly targeted approach to wildfire prevention, but, until now, long-lasting materials have not been available.

The researchers have worked with the California Department of Forestry and Fire Protection (CAL FIRE) to test the retardant materials on grass and chamise — two vegetation types where fire frequently starts. They found the treatment provides complete fire protection even after half an inch of rainfall. Under the same conditions, a typical commercial retardant formulation provides little or no fire protection. The researchers are now working with the California Department of Transportation and CAL FIRE to test the material on high-risk roadside areas that are the origin of dozens of wildfires every year.

“We don’t have a tool that’s comparable to this,” said Alan Peters, a CAL FIRE division chief in San Luis Obispo who monitored some of the test burns. “It has the potential to definitely reduce the number of fires.”

The Stanford-developed treatment contains only nontoxic materials widely used in food, drug, cosmetic and agricultural products, according to the developers. The unique properties of these gel-like retardant fluids allow them to be applied using standard agricultural spraying equipment or from aircraft. It washes away slowly, providing the ability to protect treated areas against fire for months as the materials slowly degrade.

Link to the research paper, “Wildfire prevention through prophylactic treatment of high-risk landscapes using viscoelastic retardant fluids”.

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Author: Bill Gabbert

After working full time in wildland fire for 33 years, he continues to learn, and strives to be a Student of Fire.

6 thoughts on “New fire retardant gel developed that can remain effective for months”

  1. Note that the research paper explains that the fire retarding component of this new formulation is ammonium polyphosphate, the same chemical that’s used in all current long-term retardants. The novel part of this is the suspension, based on cellulose and silica particles. That means a final product for use in aircraft will still need corrosion inhibitors and colorants. The thickener component of current retardants is a relatively inexpensive ingredient, so expect that an actual product based on this new formulation would cost at least as much as existing products. If “prophylactic treatment” were to seriously be considered, we would either need astonishing predictive capabilities to choose the best application locations using the roughly $400M currently spent annually on fire retardants, or a staggering $115Bn to treat all 33 million of California’s threatened forestland acres at CL 2.

    While the measured improvement in fire-retarding performance on standard fuel beds is laudable, the paper notes that this is a result of the improved retention by the fuels. Twenty years ago, I helped test erosion mitigation and revegetation measures for burned areas. One conceptually similar formulation of soil stabilizer with added seeds had the paradoxical effect of simultaneously reducing stormwater erosion and inhibiting seed germination. The point is that unintended effects can be quite surprising. Think of the results reported in this paper in the same light as a phase one clinical trial in medicine – very promising, but many hurdles remain before we know it’s both safe and effective.

  2. I don’t see what the use case is for this? Pre-treatment? That sounds prohibitively expensive and probably less effective than fuels treatment. I can only imagine the lawsuits stemming from this.

  3. It appears that Pyro Cool is very effective on fires, providing one has the proper equipment on hand and the skills to use it… To wit: Fire hose & nozzle, pumper, material pre-mixed, fire suits and equipment, etc… I’m not knocking or playing down the effectiveness of this stuff, but I am ill equipped to use it…
    On the other hand, they say that this new fire retardant gel can remain effective for months, even remaining effective after .5″ of rain!
    It would seem that the pro-active thing to do would be to have something of this sort to apply, (With a garden sprayer it would seem.), maybe a couple times during the summer months, and not have a fire at all, than have to try to put one out…
    Just sayin’…

  4. How about Pyro Cool? Not toxic to fish or humans and cheaper per litre than others, yet not on the “approved list”!
    Something smells here for sure!

  5. Hi Bill,
    This stuff is real interesting… I’d sure like to know more about it… Like would it be apply-able, or ever applicable to wood structures, like overhanging eaves and such? It would seem that if it might, homeowners not living in close proximity to a fire station might be a second target audience!
    Thanks for posting this!
    Ol’ Bill


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