Kydex

Kydex is a line of thermoplastic acrylic-polyvinyl chloride alloy sheet grades. It is frequently used as an alternative to leather in the production of firearm holsters and sheaths for knives. Kydex Thermoplastic Sheet is a registered trademark of Kleerdex Company, LLC and is the only manufacturer of this line of proprietary thermoplastic sheet.

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Development

Kydex sheet was originally produced in 1965 by Rohm and Haas, having been designed for use in aircraft interiors. In 1987, the product line was purchased by the Kleerdex Company, LLC[1], which manufactures the material at a location in Bloomsburg, Pennsylvania.

Characteristics as a holster material

Kydex

Kydex is an acrylic-polyvinyl chloride alloy produced by Kleerdex. Engineered for thermoforming fabrication, Kydex, combines the advantageous properties of both the acrylic and the polyvinyl chloride components. From acrylic, it obtains superior rigidity and formability; from PVC, outstanding toughness, chemical resistance and good interior finish ratings.

The combination of strength properties of Kydex places it at the highest level among thermoforming materials. Its modulus of elasticity in flexure is 330,000 psi - 50% higher than many other sheets.

Parts formed of Kydex will be much more rigid and will deform less when loaded. This is of particular importance in deep formed parts with thin wall sections. Kydex offers rigidity along with a high degree of toughness and resilience.

Kydex is a relatively hard thermoplastic with a hardness of 90 on the Rockwell R scale. In service, this excellent abrasion resistance is further enhanced by the grained surface of the Kydex sheets.

Kydex has a UL classification of 94 V-0.

Properties Outstanding breakage resistance

Excellent rigidity

Ease of thermoforming

Excellent chemical resistance

UL 94 V-0 classification

Applications

• Machine housing Instrument consoles
• Truck cargo liners Lavatory pans
• Door liners Kick plates
• Seat backs Aircraft pull-down trays
• Truck fenders Trays and tote boxes
• Motor covers Safety helmets
• Aircraft fairing Air exhaust systems

Kydex sheet is a non-porous material, which is easily molded into shape by heating, forming, and cooling the material. Typically it is supplied in sheets of varying thickness, which can be cut into shape and formed. Kydex sheet is advertised to have a number of advantages over leather in forming holsters and other similar items, including:

• waterproof
• scratch resistant with a Rockwell "R" scale hardness of 90
• holds its shape
• will not stretch or shrink under normal conditions
• low friction

These, depending on person preference, may or may not be disadvantage:

• The low friction means that Kydex thermoplastic sheet holsters must have a type of retention mechanism, where a leather holster will often rely on the natural friction for retention.

• This retention mechanism is usually preferred over button straps, because this eliminates the following unfavorable possibilities: fumbling with the straps in the dark, the straps being knocked loose, loose straps from making noise when they hit something metallic, loose straps "jingling" when shook, light reflected off the shiny, metal connectors of the buttons, the possibility of the knife flying out during a roll or fall if the straps have been disengaged or knocked loose, and finally; a knife falling out of an inverted carry(sheath is up-side down) from a combination of running, jumping, and bumps along the way that knocked the straps loose and allowed the gravity to run its course. The same could happen if the knife were carried in the traditional position with the prime factor being inertia instead of gravity, it is quite rare for that to happen, however.

• The low friction and quick release of the retention device may allow a smoother draw, but it may also provide significantly more wear on the firearm's finish where it engages the retention device.

There are also some disadvantages to Kydex sheet. Kydex thermoplastic sheet cannot be molded without high temperatures, and so a Kydex sheet holster must be formed to its final shape by the manufacturer, where a leather holster will naturally tend to stretch and conform to both the gun and the wearer. Since KYDEX® sheet is a thermoplastic, not only does it get soft at high temperatures, but it also gets harder at low temperatures, and may become brittle in cold conditions.

References

• Kleerdex Company website
• "Pros and Cons of Kydex"
• Report on the durability of Kydex at low temperatures
• [2] Kydex use in Multi Podus Boots (RCAI type)]