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What is a Bulletproof vest made of?

What is a Bulletproof vest made of?
Many layers of woven aramid or polyethylene fibre that catch and deform a bullet; rifle threats need a ceramic plate.

Soft armour does not bounce bullets off; it deforms them into a mushroom shape and drags on them across dozens of fabric layers, converting the energy into fibre stretch and friction over a few milliseconds. This makes it excellent against handgun rounds and largely useless against rifle rounds, which is why hard plates exist and why rating levels — NIJ 0101.06 and the newer 0101.07 — specify exactly which threats a panel has been tested against. Armour also expires: the Zylon recalls of the early 2000s showed a fibre losing strength faster than expected in heat and humidity, and vests now carry a warranty life, typically five years, that is a safety limit rather than a sales device.

Component by component

Every material is a choice, and the third column is the constraint that drove it.
Part Material Why that material
soft armour woven para-aramid (Kevlar, Twaron) or laminated ultra-high-molecular-weight polyethylene (Dyneema, Spectra) These fibres have enormous tensile strength and stretch very little, so they catch the bullet and spread its energy across many layers.
rifle plate boron carbide, silicon carbide or alumina ceramic on a polyethylene backing A rifle bullet cuts straight through soft fibre; the ceramic shatters and blunts it first, and the backing catches the fragments.
cover waterproofed nylon or polyester with a sealed carrier Aramid loses ballistic performance when wet and degrades in ultraviolet light, so the cover is part of the protection.
trauma pad foam or additional fibre layers behind the panel The vest can stop penetration and still transmit enough force to break ribs; the pad limits backface deformation.

Other clothing and kit objects

Common questions

What is a Bulletproof vest made of?
Many layers of woven aramid or polyethylene fibre that catch and deform a bullet; rifle threats need a ceramic plate.
What is the soft armour of a Bulletproof vest made of?
Woven para-aramid (Kevlar, Twaron) or laminated ultra-high-molecular-weight polyethylene (Dyneema, Spectra). These fibres have enormous tensile strength and stretch very little, so they catch the bullet and spread its energy across many layers.
What is the rifle plate of a Bulletproof vest made of?
Boron carbide, silicon carbide or alumina ceramic on a polyethylene backing. A rifle bullet cuts straight through soft fibre; the ceramic shatters and blunts it first, and the backing catches the fragments.

Related pages

Sources

  1. Typical range compiled from manufacturer specifications — At One Place

How these figures are compiled and checked