What Is Waterproof?

A waterproof jacket or a raincoat is an essential piece of outdoor gear. Having a waterproof backpack or sling bag is also useful to protect your camera equipment, important documents and other essential items during wet weather. Even a waterproof pencil case is handy for jotting down notes without the risk of smudging or tearing. If you work in a wet environment, such as a marine biologist or biology student, or spend a lot of time outdoors, having the right waterproof tools will help to keep your things dry.

Waterproof is a term that gets used frequently in the clothing and outdoor industry, so it's important to understand what exactly waterproof means. Most people associate waterproof with an item that keeps out water completely, which is not always the case. A lot of waterproof products have a membrane inside that allows perspiration to escape while keeping moisture out. This is typically a Teflon-based membrane that is treated to create a waterproof barrier.

The water resistance of a garment or fabric is usually tested using a hydrostatic head test, which tests the material or item by exposing it to increasing amounts of water pressure until penetration occurs. This type of testing does not account for other forces, such as sweat or the pressure of a heavy pack on the fabric, which can cause leakage. Typically, a waterproof garment will be able to withstand up to 10 psi of water pressure.

Water-resistant paper is a popular choice for school notebooks and other work materials that may get exposed to moisture or spilled liquids. Many national parks, ski resorts and other outdoor destinations print trail maps on waterproof paper to prevent guests from getting lost with illegible or water-damaged directions. Similarly, waterproof printer papers are an excellent option for workers in the food service or manufacturing industries, where toppled water glasses and greasy fingerprints can result in dozens of discarded menus each day.

There are a wide variety of waterproof products available for almost any environment, including the incredibly durable ripstop nylon, which is often used in backpacks, tents and waterproof jackets. A ripstop nylon item can be made fully waterproof with the addition of specific treatment chemicals, such as polyurethane and vinyl ester.

MIT engineers have developed a new coating that is able to add waterproof qualities to natural fabrics, including cotton and silk. The coating consists of long chains of molecules that are similar to the molecules found in plant oils, and the resulting structure is able to repel drops of water more effectively than existing waterproofing chemicals. The researchers hope that the technology will be a viable alternative to the chemical treatments that have been used to make waterproof clothing, shoes and other items for decades. This new technology could be a game-changer for the fashion industry, as current waterproofing chemicals are not ecofriendly and can lead to toxic buildup in the environment and human body. Eventually, these chemicals will need to be replaced.