Kevlar boot laces are made for the long haul. They're engineered for strength and resilience, making them a top choice for heavy-duty activities. Here's what you need to know
It Starts with Aramid
Aramid is a generic description of a range of organic fibers that are characterized by their resistance to heat, as well as their strong mechanical properties. Common uses include in ballistic protective applications, aerospace, and tires (Hanh 2022,).
Para-aramid fibers are a specific type of aramid fibers that have their polymer chains oriented parallel to the fiber's axis. This parallel orientation gives para-aramid fibers exceptional tensile strength, making them five times stronger than steel at the same weight. Kevlar® is a well-known brand of para-aramid fibers and is often used in bulletproof vests and other protective gear (Dupont).
Unlike para-aramids which emphasize strength, meta-aramid fibers are designed for superior resistance to heat, chemical degradation, and fire. Their molecular structure differs from para-aramids in that the molecules are oriented in a less organized, more random pattern. This randomness contributes to their high thermal and chemical stability. Nomex® is a famous brand of meta-aramid, commonly used in fire-resistant clothing and materials (Dupont).
"Advanced para-aramid fibers" is not a standardized term within the materials science industry. In the last several years it has been appearing in marketing and product promotion.
So, para-aramid, is Kevlar, the strong type of Aramid Fiber. Now let’s see how para-aramid (Kevlar) boot laces stand up.
How strong are Kevlar Boot Laces?
The tensile strength of Kevlar is incredible. It's many times stronger than steel and still lighter than carbon fiber. It's been such a revolution in materials science since its discovery by Stephanie Kwolek at Dupont in the 60's. Kevlar boot laces are among the strongest available.
In the table below, aramid (Kevlar) ropes are evaluated on tensile strength, and abrasion resistance. These are two important measures for assessing the strength of Kevlar boot laces.
Interestingly, the abrasion resistance of the polyester fiber out-ranks both Aramid, and ultra-strong UHMWPE ropes in laboratory testing.
However, abrasion resistance must be considered along with strength. On balance, while Kevlar is an acceptable material for strong boot laces, UHMWPE performs better than both aramid, and polyester.
Aramid |
Strength: Very High (19-23 g/den) |
Abrasion Resistance: Poor (300 cycles) |
UHMWPE |
Strength: Extremely High (32-35 g/den) |
Abrasion Resistance: Very High (4,115 cycles) |
Polyester |
Strength: Poor (5.5-8.5g/den) |
Abrasion Resistance: Extremely high (48,324 cycles) |
Strength is the force the rope can withstand before breaking
Abrasion Resistance is The number of times the rope can be rubbed against itself before 3% of it deteriorates
Do Kevlar Laces Stay Tied?
Kevlar fibers have a special texture that helps knots stay tight. But the stiffness of Kevlar boot laces works against them, creating knots that easily loosen.
Kevlar Laces vs. Acids and Alkalis
Kevlar boot laces are almost free from the impact of organic solvents and oil except for strong acid and alkali.
Kevlar can resist erosion from organic solvents like paint thinner, benzene, aviation fuel, and others. This makes it a good choice for mechanical work indoors around fuels and solvents ( Ru-Min Wang, Ya-Ping Zheng, in Polymer Matrix Composites and Technology, 2011 )
Kevlar Boot Laces vs. Sun Exposure
UV exposure is the achilles heel of kevlar. Prolonged sun exposure will reduce the strength of the material (Wang, Zheng, and Zheng 2011).
Kevlar Boot Laces vs. Moisture
Kevlar can handle modest moisture levels, like the moisture in the atmosphere on a humid day. When they're saturated with water, Kevlar boot laces can lose considerable strength (Ericksen, and Orear 1979). This makes them less than ideal for use outdoors, or in maritime applications.
Kevlar Boot Laces vs. Flame
Kevlar is flame-resistant. It won't melt, and it's unlikely to catch fire. Dupont has published some impressive tests comparing the burn rate of a Kevlar glove vs. a plastic one. (ouch!). Kevlar bootlaces are a great choice for work around heat or flame like fire fighting and welding.
Price of Kevlar Boot Laces
Kevlar is a premium material. Bootlaces made from Kevlar will generally be more expensive than standard synthetic laces. Considering their strength and longevity, they often provide good value.
Kevlar Boot Lace Style
While Kevlar doesn't offer the classic look of leather, it can still provide a sleek, professional appearance. Generally Kevlar boot laces blend in with most footwear. It's often available in various colors and finishes to match your footwear.
Other factors to consider for Heavy Duty Boot Laces
When evaluating heavy duty boot laces, there are many factors that impact what makes a great boot lace, from length, to material, to wax treatments. Find it all in our Boot Lace Buyer's Guide.
Conclusion
Kevlar boot laces are a powerful and reliable choice, especially if you're looking for something strong and durable. They handle fire and chemicals like a champ and they're unlikely to snap. When it comes to functionality, we like our laces to stay tied and stand up to UV rays. So in our opinion, UHMWPE is a better choice for Ultra-strong laces, if you need them.
