What Makes a Material Waterproof?

Cotton and polyester fabrics can be treated with a chemical waterproofing agent.

Waterproof material repels water without allowing it to pass through the weave of the fabric. Some fabrics are manufactured with a coating while others can be treated at home to become waterproof.

Manufactured

Fabrics manufactured and marketed as waterproof are tightly woven. The gaps between the woven threads are smaller than a drop of water, preventing the liquid from passing through. Ripstop nylon is an example of this type of material.

Other waterproof fabrics are coated, usually with rubber. The rubber seals the gaps between the thread. The most common rubberized material available is vinyl.

Temporary Waterproofing

Cottons, polyesters and combinations of the two can be treated at home to have temporary waterproof characteristics. Multiple products exist under different brand names. The material is washed with these chemicals, which coat the fabric or item. Over time, the waterproofing wears off and will need to be reapplied.

Specialty Fabrics

Fabrics such as Gore-Tex have revolutionized the waterproof fabric industry. While vinyl is waterproof, it is not breathable. Gore-Tex offers both waterproofing and breathability. It is a top material for recreation and sport outdoor applications, according to its manufacturer, W.L. Gore & Associates.

Gore-Tex has three layers which create the waterproof effect. Between the three layers, drops of water are kept from penetrating.

References

• Active Sports Online: Waterproof Breathable Jackets
• Gore-Tex: About
• Seattle Fabrics: Waterproofing
• Sierra Trading Post: Waterproof Gear Guide