Armadillo Merino USA Wool - Natural Flame Resistance

The merino wool that we use has many unique performance properties and here we examine the fiber's naturally occurring flame resistance (FR). Our natural FR is generating interest as we're hearing more and more about the importance of firefighter health and well- being and growing concerns about their toxic clothing and fast fashion. Companies are adding countless, unsafe chemicals to fabrics in order to make them flame resistant. When these chemically treated fabrics are exposed to heat or flames, they produce hazardous gases (off-gassing). When these toxic gases are inhaled by the wearer or absorbed through the skin, they disrupt the endocrine system and over time cause chronic illnesses and cancer. With these facts in mind and personal health issues inflicted by their current station wear, the naturally occurring fire resistance of merino wool is what cultivated the idea of our co-founders to create the healthiest and safest station wear, Armadillo Merino USA.


Our wools natural flame resistance is due to its unique fiber structures made up of nitrogen (14%) combined with a high relative moisture content that displays the following beneficial properties:

● A very high ignition temperature (570-600°C)
● Doesn’t melt or stick
●Forms an insulating char and self-extinguishes
● A high Limiting Oxygen Index (20- 25%) – with the LOI being a measure of the minimum % of oxygen required to sustain combustion
● A slow rate of combustion and heat release


Wool requires higher levels of oxygen in the surrounding environment in order to burn. Wool may ignite if exposed to a naked flame, but it won't support the flame. It will smolder without any toxic fumes. Take the flame away and it self-extinguishes. Merino wools cross-linked cell membrane structures swell when heated to the point of combustion leaving a char, insulating layer that prevents the spread of flame.

Of the commonly used textiles and fibers (cotton, rayon, polyester, acrylic and nylon), wool is widely recognized for its flame resistance noted in the summary below.


● Natural flame resistance, and its performance exceeds all other commonly used textiles and fibers.
● Has a low rate of combustion and heat release.
● Does not melt or stick.
● Self-extinguishing once the initial ignition source is removed.

The wearer is often unaware of the extreme dangers they are exposing themselves to when wearing "moisture wicking" synthetic base layers and clothing. There is no place for chemically treated flame-resistant base layers in our first responder community!

When you consider all of the above, the case just keeps getting stronger for merino wool. It is the safest and healthiest option for all first responders for next-to-skin clothing and their last line of defense. Armadillo Merino USA was created to protect our fellow brother and sister firefighters and first responders alike.