Kevlar boot laces are made for the long haul. They're strong enough to stand up to most applications, and they won't burn. Here's what you need to know
Kelvar Shoe Strings Start with Aramid
Kevlar® is a well-known brand of para-aramid fibres and is often used in bulletproof vests and other protective gear (Dupont).
Aramid is a generic description of a range of organic fibres 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 fibres are a specific type of aramid fibres that have their polymer chains oriented parallel to the fibre's axis. This parallel orientation gives para-aramid fibres exceptional tensile strength, making them five times stronger than steel at the same weight.
Unlike para-aramids which emphasize strength, meta-aramid fibres 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 fibres" is not a standardized term within the materials science industry. In the last several years it has been appearing in marketing and product promotion.
How strong are Kevlar Laces?
The tensile strength of Kevlar is incredible. It's many times stronger than steel and still lighter than carbon fibre. 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 fibre 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 fibres have a special texture that helps knots stay tight. But the stiffness of Kevlar boot laces works against them, kevlar shoe strings soften over time as they "break-in".
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 Shoe Strings 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: Fire Resistant Boot Laces
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. Expect to pay around $15-$18 a pair. Considering their strength and longevity, it's a good deal.
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 colours but in our experience producing aramid laces, black and a grey-ish yellow are the only colours that seem to stay permanently.
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
You can't beat Kevlar boot laces if you're looking for flame resistance. They handle fire and chemicals like a champ and they're tough enough, unlikely to snap. If you're outside a lot, and you don't need the flame resistance, UHMWPE is a better choice. It's stronger, more chemical resistant and more UV resistant.
More on Boot Laces
Looking for more info on boot laces?
- Here's our blog post on the best laces for work boots.
- Find our Complete Boot Lace Buyer's Guide here. It's an in-depth review of everything you need to know about boot shoe laces
- Find the Boot Lace Length Chart Here to make sure you get the right length for your boot laces.
- Learn about the three ways to tie your boot laces for a blister-free day.
