Field shirt M91, Green

Field Polo Shirt M91 – Military-Grade Quality Exceeding Standards

The Origopro M91 is an exceptionally versatile raglan-sleeve field shirt familiar from service with the Finnish Defence Forces. Origopro has served as the official contract manufacturer of these shirts for the Finnish Defence Forces for many years—and now, this same uncompromising military-grade quality is finally available for civilian use.

The forest green Field Polo Shirt M91 is not made from standard military fabric; its high-performance material meets and even exceeds official Defence Forces requirements for both durability and safety.

Years of Development and Maximum Flame Resistance (LOI 28+)

Origopro has spent years developing a knit fabric that delivers exceptionally high and reliable flame protection. The resulting fabric boasts a LOI (Limited Oxygen Index) value of over 28, meaning the material is self-extinguishing and will not sustain burning or support a flame under normal atmospheric oxygen levels.

This unique material development makes the M91 Field Polo Shirt an extremely safe and dependable choice for tactical operators, first responders, and demanding outdoor environments.

Why Doesn’t the Fabric Sustain Combustion? (LOI 28+)

The fabric’s flame resistance relies on the unique structure and oxygen index of Kanecaron® modacrylic fiber (LOI 28+):

• Normal Air Is Not Enough for Combustion: Normal ambient air contains approximately 21% oxygen. Because the fabric’s LOI value exceeds 28, it requires an oxygen level of at least 28% to maintain combustion. In standard air, the flame automatically extinguishes as soon as the external heat source (such as a lighter or spark) is removed.

• Gaseous Protective Barrier: When exposed to heat, the modacrylic fiber releases flame-inhibiting gases that displace oxygen from the fabric’s surface, smothering the flame at its inception.

• Charring (Carbonization): Upon contact with flame, the modacrylic rapidly forms a protective, non-deforming carbon char layer. This charred layer acts as a thermal barrier and prevents oxygen from penetrating deeper into the fabric.

Does the Fabric Melt or Stick to the Skin?

No, it does not. This is one of the fabric’s most critical safety features compared to standard synthetic garments:

• Standard Polyester/Nylon: Melts into a liquid “plastic” under intense heat, sticking to the skin and causing severe, deep burns.

• This Special Knit: The blend of modacrylic and cotton is completely no melt, no drip. Under extreme heat, the material only chars and hardens.

• Synergy of Materials: Cotton adds softness and absorbency to the knit, while modacrylic prevents the cotton from continuing to burn.

The result is a textile that gives the wearer critical extra time to react in emergency situations without the danger of melted fabric sticking to the skin.

Material and Construction

The shirt combines the flame protection of modacrylic, the breathability and softness of cotton, and the durability and shape retention of polyester. The raglan sleeve construction ensures excellent freedom of movement and comfort, even under a backpack or load-bearing equipment.