How to Identify Waterproof Fabrics

There are many different types of waterproof materials and objects. Some are designed to keep water out, while others are designed to help moisture escape.

Waterproof materials are useful in a variety of applications, from building structures to clothing, as well as electronics and paper packaging. But defining exactly what makes something waterproof is more difficult than it seems. In fact, there is not one specific industry standard for what can be called waterproof. Companies take a calculated risk when they label products as waterproof, as there is no guarantee that the product will not experience water damage under certain conditions.

In a general sense, waterproof means that a material or object is impenetrable to liquid water. However, it is important to note that a material or item can still be damaged by water vapor, which is the moist air that is produced when we sweat. This is why it is important to separate waterproof and water-resistant when discussing fabrics or products.

To be considered waterproof, a fabric must have sealed seams that make it hard for water to penetrate the fabric. The simplest example is cotton – it can be woven so tightly that the pores are very small, making it difficult for water to pass through. This type of fabric is commonly used in raincoats and waders.

More recently, a number of different synthetic and natural fabrics have been treated to be waterproof. These treatments can be applied either during manufacture or to completed products - for example, by a waterproofing spray. This is what allows us to create a waterproof jacket, for example.

One of the most popular and best-performing waterproof fabrics available is Gore-Tex. These fabrics utilise an ePTFE membrane to create a very thin layer that is both breathable and waterproof. When paired with a Gore-Tex precise lining construction, these fabrics are able to offer protection from leisure activities right through to professional sports and outdoor events.

To test whether a fabric is waterproof, scientists put the fabric in a tray of water for a given time period. The amount of water that passes through the fabric is recorded and then compared to the water-repellent properties of other materials. This data helps to determine how much water the fabric can resist before it will eventually let water pass through, and how effective its sealed seams are in keeping moisture out. To learn more about how to identify a waterproof fabric, see this helpful teaching resource.