Leather, Nylon or Kydex: How Do Sheaths Differ?.

Kydex, leather and nylon as each maker uses the word

On the knife makers' own pages, the three words cover different ground:

• Kydex: a trade name for thermoplastic sheet. CIVIVI, Buck and Kershaw each print it as the sheath material on some of their fixed blades, and the Kydex entry traces the name to its owner and quotes their wording.
• Leather: Buck says its sheaths come in nylon or genuine leather, Case's leather sheath pages describe each as a "genuine leather sheath," and CIVIVI lists "Sheath: Brown Leather Sheath."
• Nylon: Kershaw lists glass-filled nylon sheaths that it calls molded, Buck's catalog lists "Injection-molded nylon" sheaths, and Hogue and Gerber name ballistic nylon. Kershaw and Buck also list polypropylene sheaths under that name.

Sheath wear, and putting the knife back

On putting a knife back, Gerber's product care page says "Never use excess force to replace your Gerber knife or machete within its sheath." On wear, Buck's view is that the sheath is likely to wear out long before the knife, a point taken further in replacing a knife sheath.

Preparing a knife to sit unused for months is a separate question, the subject of storing a knife long term, and the sheath as a safety device is where the answer on safe fixed-blade carry begins.

Where the makers say nothing, and where listings differ

None of the makers cited here ranks leather, nylon and Kydex, pairs one with a use, or defines nylon; each describes its own sheaths. Nor do their pages say that one material is harder on a blade than another.

The words also differ between documents. Buck's sheaths page says nylon where Buck's 2026 catalog says polyester for some models' sheaths, and the supplier text in the product data calls some Kershaw sheaths injection molded where Kershaw's own pages say molded, glass-filled nylon. For one knife, set the listing beside its maker's own description.