The first PEI/Ultem knife made by FREETIGER - FT81
What is Ultem Material?
Ultem is the brand name for a high-performance thermoplastic polymer known generically as Polyetherimide (PEI). It was originally developed by General Electric Plastics (now owned by SABIC) and is considered a top-tier engineering plastic due to its exceptional combination of properties. In simple terms, it's often described as the "special forces" or the "overachiever" of the plastics world.
Advantages of Using Ultem for Knife Handles
Ultem (PEI) is a premium choice for knife handles, particularly in high-end, tactical, and professional-grade knives. Its combination of material properties offers several distinct advantages:
Exceptional Strength and Rigidity
High Strength-to-Weight Ratio: Ultem possesses strength and stiffness that rival some metals. This results in a handle that is incredibly durable and resistant to impact, bending, or deformation under heavy use.
Dimensional Stability under Load: It does not flex or "creep" over time, ensuring a secure and permanent fit with the knife's tang.
Superior Heat Resistance
Will Not Warp or Soften: With a glass transition temperature of 217°C (423°F), Ultem handles are completely unaffected by high temperatures. They can be left in a hot car, exposed to direct sunlight, or used in high-temperature environments without any risk of softening or deforming.
Sterilizable: For hunting, fishing, or survival knives, the handle can be sterilized using boiling water or steam without damage, which is a significant hygienic benefit.
Outstanding Chemical and Solvent Resistance
Impervious to Common Corrosives: Ultem is highly resistant to skin oils, sweat, salts, fuels, most oils, and common cleaning agents. It will not degrade, become sticky, or discour when exposed to these substances, unlike some other polymers.
Resists Insect Repellent (DEET): This is a critical advantage for outdoor knives, as DEET is known to damage and melt many other plastics (e.g., ABS, PVC) but does not affect Ultem.
Inherent Flame Retardancy
UL94 V-0 Rated: Ultem is naturally flame-retardant without any added chemicals. In a direct flame, it will char and self-extinguish rather than sustain combustion. This provides an added layer of safety in extreme scenarios.
Excellent Dimensional Stability (Moisture)
Zero Water Absorption: Unlike materials like G-10 or Micarta, which can absorb minute amounts of moisture, Ultem is completely hydrophobic. It will not swell, warp, or change weight when submerged in water or used in humid environments, guaranteeing a consistent feel and perfect fit.
Lightweight
Despite its high strength and robustness, Ultem has a relatively low density, contributing to an overall lighter knife without compromising durability or feel.
Unique Aesthetic and Grip
Signature Amber Transparency: The classic Ultem 1000 series is known for its distinctive amber, semi-transparent appearance. This offers a unique, high-tech look that is highly valued by collectors and enthusiasts.
Good Grip Machinability: It can be machined with texturing like checkering or stippling to provide a secure, non-slip grip. Its surface can be finished in various ways, from a smooth polish to a gritty texture.
Potential Considerations
Cost: It is significantly more expensive than common handle materials like FRN (Fiberglass Reinforced Nylon), G-10, or even standard Micarta.
Feel: It is very rigid and hard. Compared to materials like Micarta, it can feel less "organic" or warm in the hand. In cold weather, it will feel colder to the touch.
Color Options: While its amber hue is iconic, it limits color variety. Colored versions (e.g., black, red) are available but are less common than the classic translucent amber.
We made the FT81 using PEI/Ultem
Specifications
Total length:20.7cm / 8.15''
Blade length:9cm / 3.54''
Handle length:11.7cm / 4.60''
Blade thickess:4mm / 0.16''
Blade width:3cm / 1.18''
Handle thickness:1.5cm / 0.59''
Handle width:2.6cm / 1.02''
Blade: D2
Blade Finished: Sandblasting + Brushing / Black Titanium Coating
Handle: PEI/Ultem
Weight:150g / 5.29oz
Steel Ball Bearing
Lock Type: Liner Lock
Advanced Blade & Deployment
At the heart of this tool is a D2 steel blade, known for its high carbon content and superior edge retention, making it resistant to wear during demanding cutting tasks. The blade is available in two finishes: a sleek Sandblasting + Brushing for a raw, industrial look, or a rugged Black Titanium Coating for enhanced corrosion resistance and a non-reflective tactical appearance. Deployment is smooth and effortless thanks to a Steel Ball Bearing pivot system, while a secure Liner Lock mechanism ensures the blade stays firmly in place during use.
Ideal Application Scenarios
This knife is a versatile companion built for both everyday carry (EDC) and more demanding situations. It is perfectly suited for:
Outdoor Tasks: Camping, hiking, and preparing kindling.
Tactical Use: Its robust build and reliable lock make it a dependable option.
General Utility: From opening packages to cutting ropes in workshops.
Everyday Challenges: A trustworthy tool for any situation that requires a sharp, durable blade.
In summary, this folding knife combines a tough D2 blade, a versatile and durable Ultem handle, and a reliable locking mechanism into a compact, ready-to-deploy package for the discerning user.