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What is Kydex?

by Ben Jimenez

kydex gun holster and bullets

Kydex is a material that has been with us since the mid ’60s, originally designed for use in aircraft interiors. It has been adapted to a multitude of other industries and products, from auto body parts, safety helmets and insulators to trays and telescope bodies. Of interest to the firearm community is the adaptation of Kydex as a material for knife sheaths and holsters.

Kydex was first used as a holster material in 1972 by an enterprising young FBI agent named Bill Rogers. He was tired of the stretching, sagging and deformation of the leather holster from use and made his own from the new material. His work caught on with the rest of the Chicago Bureau, and the demand spread so rapidly that Rogers took a three-year leave from the Bureau to make holsters.

kydex sheets
Kydex sheets ready for forming

It took another two decades for synthetic materials to become a mainstream alternative to traditional leather. In that time, two alternate methods of manufacturing rigid synthetic holsters emerged: molded Kydex and injection molding.

What exactly IS Kydex?

Developed in 1965 by Rohm and Haas, Kydex is a thermoplastic acrylic-polyvinyl chloride whose construction gives the plastic rigidity while also allowing it to be molded into various shapes. Engineered for thermoforming fabrication, it combines the properties of the acrylic (rigidity and formability) and the polyvinyl chloride (durability and chemical resistance) components.

A relatively hard thermoplastic, Kydex has a hardness of 90 (!) on the Rockwell R scale (gun barrels are typically 26-40 Rockwell). This hardness, combined with a grained surface, increases its abrasion resistance.

All of that means it is a lightweight, durable polymer that is easily formed when heated. It can be vacuum-formed to create a perfect fit and can yield a thinner profile than injection-molded counterparts.

Also, Kydex holsters tend to offer durability, strength and overall better retention than its injection-molded counterpart.

Those Injection-Molded Alternatives

In use in various forms since the mid-1800s, injection molding utilizes a blend of molten materials (most often a nylon polymer) injected into a mold. This process lends itself to volume production, lower manufacturing costs and consistency. The tradeoff is overall quality where an injection-molded holster can wear out faster than a Kydex counterpart and may not exhibit the precise fit of the more expensive alternative.

Despite the differences in manufacturing methods, the finished product (mostly) functions the same. Both adequately retain a handgun, though Kydex tends to fit model variations slightly better. Both retain their shape and are waterproof with the ability to easily wash dirt, sweat and grime away. Molded holsters tend to be slightly thicker, adding to the overall “print” signature of a CCW rig.

Alternative to Leather

Leather holsters, like wood grips, have plenty of character but practical downsides. They need a break-in period, retain moisture and sweat, absorb oil, deform with the gun removed and stretch and sag with age. Kydex suffers none of these liabilities, with the added bonus of having a lower friction coefficient (that means a faster draw time).

worn leather holster

Worn Out Holster

The same shooter, using the same gun, will be faster on target and can use that time to make a better shot. That’s why every competition holster made today is synthetic. Unless you are shooting in a Cowboy Action match (which are loads of fun), you won’t see any leather holsters on the firing line.

Over time, a gun repeatedly drawn in and out of any holster will show signs of finish wear. Leather holsters tend to wear on a wider area of the gun, and the tannins in the leather are actually corrosive over time. A Kydex holster will wear on the contact points where the gun “clicks” in. Holster wear on a gun is like a well broken-in leather jacket or an old faded pair of jeans. It’s instant street cred, and can only be earned after countless repetitions of the draw stroke and riding thousands of miles on the hip. It’s like scars for guns–wear it with pride. There is no holster that will not eventually wear on a gun. With that being said, KYDEX™ has a very smooth inner surface which is not as abrasive as hard plastic or leather. KYDEX™ holsters will preserve the finish better than any other material option.

kydex handgun holster with bullets
Sort of like the jewelry ads–“Kydex is Forever”…AKA, the last holster you’ll ever need

Will Kydex break?

Typically, no. However, if abused, it will break or lose its shape. If severely stressed, it can develop cracks at stress points–like if you run it over with your car.

Another automotive caution is to never leave your Kydex holster on your dashboard or in other extreme heat conditions as it may reach a “working” temperature and deform.

Quality manufacturers typically use .08-inch KYDEX™ since it offers the best balance of durability and lightweight, all-day comfort.

If your holster, knife sheath or mag pouch is equipped with screws or other hardware, be sure to apply Loctite to all fasteners to ensure positive retention.

Let’s face it, leather is cool. It even smells good. But for daily practical use, it has seen its time. As the older “steel, wood and leather” generations make room for the younger “polymer” generations, the prejudices against synthetics have largely disappeared (but not entirely). If your daily carry setup is intended to deliver maximum performance, you’ll eventually find your way to a Kydex holster manufacturer.

Ben Jimenez
Ben Jimenez


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