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The Science Behind Wicking

This article explains some of the technical information about wicking.

What we commonly refer to as “Kevlar” is commercially known as an aramid braided rope or aramid flat tape (flat wicking). Its composition is a blend of Kevlar (a Registered Trademark of Dupont), fiberglass, and small amounts of various other heat-resistant and/or abrasion resistant materials. Specialty textile manufactures weave these raw fibers into tape and rope products, which are most typically used for high temperature gaskets (furnace doors), pipe insulation in high-abrasion situations, personal body armor, and to reinforce resin-based materials.

The braided aramid ropes and flat tapes are made out of a yarn comprised of a mostly Kevlar outer sheath and a mostly fiberglass core.(1) The resulting product can withstand high wear and abrasion (for spinning, this would include drops and scuffs against the ground) as well as high temperatures like those white gas flames can create (as high 2200°F). Kevlar’s high temperature disintegration point is between 800-900°F, which means it cannot be used in its pure state or a fire prop’s wick would degrade relatively quickly. However, Kevlar is extremely resistant to abrasion, and therefore serves well as an exterior protection layer. Fiberglass has a much lower resistance to abrasion, but has a melting point above 2000°F.  It is the fiberglass that gives these materials the ability to withstand the repeated heat cycles that we subject them to.

As fire equipment wicks are used, the repeated exposures to sustained high temperatures and periodic surface impacts result in the yarn’s Kevlar strands disintegrating, leaving just the fiberglass core. This can be observed in heavily used wicks, when the yellow Kevlar has burned away leaving just the white-colored fiberglass fibers. You may also notice that, once the abrasion resistant Kevlar strands are removed, your wicks begin to degrade faster from striking the ground.

 

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To ensure a long lifespan for your wicks, see our article “Maintaining Your Equipment.


(1) Each manufacturer of Kevlar wicking uses a proprietary combination of materials, which can result in small differences between the properties of the tapes and ropes produced.

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