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Retardants reduce the flammability of combustibles by chemical action,
and are effective at slowing down or stopping a fire from spreading. So what should you know
about these chemicals? If you choose to use retardants, see the Qualified Products List
for appropriate products and proper mix ratios. Next, low viscosity retardant can be applied with
standard fire engine nozzles if it is batch mixed beforehand. Dispensing retardants from engines can
be viable to pre-treat fuels, provided the mixing infrastructure to support it is available nearby.
But, be aware that storing liquid concentrate and mixing on a fire engine may not be practical.
Like foams and water enhancers, retardants can be used in a direct or indirect attack.
While water enhancers and foams may be better suited for a direct attack, a retardant can also
be used as a direct attack suppressant. In this case, a retardant can be used to suppress the
flame front in fine fuels while simultaneously building a contingency reinforcement line to
guard against re-ignition. Retardants are the primary wildland fire chemical used for
indirect attack operations, and are used to slow the fire or reinforce an existing line.
Use your retardant to treat a line prior to backfiring or burning out.
You can expect the retardant to last for multiple days, as long as no rain, snow, or high winds
are expected. Retardant is most effective when it is placed ahead of the fire, allowing the fire to
burn into the retardant line. Using the entire width of the line allows the chemical reaction
between the retarding salts and the heat of the fire to occur, decreasing its intensity.
Like foams and water enhancers, retardants can also be used for structure and resource protection,
and with prescribed fires. Retardants can also be used to protect telephone poles, cell phone
and microwave towers, and wood fences. When using a retardant for structure and resource protection,
be aware that the red colored retardants have the potential to permanently stain finishes. Fugitive
colored, and uncolored, products may cause less staining. Also, be aware that a retardant is
heavier than water. Take care to avoid damaging structures during application. Retardants can
be applied to adjoining fuels to slow the fire. This can be done well in advance of the fire.
There are also commercially available residential systems that use retardant to protect individual homes.
For prescribed fires, you can use a retardant to reinforce an existing line,
or you can use it to pre-treat a line prior to burning. Again, the retardant will last
multiple days as long as no rain, snow, or high winds are expected. Either way, your retardant
line will last longer than using either foam or water enhancers. The USDA and US Forest
Service have produced a series of videos that discuss wildland fire chemicals in more depth.
We hope you'll view each one to learn more about these important topics. You can also find more
details on the Wildland Fire Chemical Systems website. Here you'll find information on safety,
environmental issues, product quality, mixing ratios, aerial delivery systems,
and other topics related to knowing when and how to use wildland fire chemicals.