Superior Chemistry


Fire Suprression

Superior Efficacy

Fortress fire retardants are significantly more effective than the current industry standard. How do we know? The United States Forest Service requires rigorous burn testing to qualify new retardants for use in the field, and our magnesium chloride formulations greatly surpassed the burn reduction achieved by conventional ammonium phosphate. To be more specific, our dry formulation yielded a 23% greater burn reduction index¹ and our wet formulation yielded a 30% greater burn reduction index, demonstrating a wide margin of improvement that adds up quickly in the field.

Superior Chemistry

The unique chemistry of our proprietary magnesium chloride formulations brings a new and multi-faceted set of fire suppression capabilities to the frontlines of firefighting. Fortress fire retardants provide a thermally responsive, staged reaction scheme that hydrates, cools, delays ignition, and disrupts combustion. Together, these reactions make for stronger firelines and superior fire control. Read our chemistry whitepaper to learn more.




Hygroscopic Hydration

The low critical relative humidity² (CRH) of magnesium chloride causes it to pull moisture from the air and stay hydrated.

33% humidity or greater

Endothermic Dehydration

Hydrated magnesium chloride responds to increasing temperatures by releasing water molecules, and absorbing heat in the process.

Occurs at 160°F, 270°F, 340°F, 390°F, and 780°F

Volatile Gas Displacement

Water vapor dilutes flammable combustion gases and displaces volatile decomposition products, lowering the probability of ignition.

Occurs at 160°F, 270°F, 340°F, 390°F, and 780°F

Catalyzed Charring

Magnesium chloride catalyzes low-temperature charring, reducing the availability of flammable compounds.


The Wall Effect

Charring in the presence of magnesium chloride generates an inert layer of magnesium oxide, ash, and other compounds that prevent further burning.

340°F to 780°F

Radical Deactivation

In the end-stage decomposition of magnesium chloride, chloride ions directly interfere with combusting free radicals, inhibiting the spread of fire.



1. Burn reduction tests are done by igniting retardant-treated test beds of Aspen Excelsior and Ponderosa Pine needles. Each product treatment is matched with a treatment of 10.6% weight diammonium phosphate (DAP). Test beds are burned on the same day along with an untreated bed of the same fuel. Reduction index is calculated by comparing the rate of flame spread and rate of weight loss of the retardant beds to the untreated beds.
2. The critical relative humidity (CRH) of a salt is defined as the relative humidity of the surrounding atmosphere (at a certain temperature) at which the material begins to absorb moisture from the atmosphere and below which it will not absorb atmospheric moisture.

If you would like more information about Fortress fire retardants, please contact:

(530) 208-3234

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