Waterproof And Breathable

Definition and Overview

Waterproof and breathable is a function that combines waterproofness and moisture permeability. In general, it is achieved by applying a membrane or coating to the back side of the textile, or by laminating a waterproof film. It is not the name of a specific type of woven or knitted outer fabric.

Waterproofness refers to the performance of preventing rainwater from entering from the outside, while moisture permeability refers to the performance of allowing water vapor generated inside clothing by sweat and the like to move outward more easily. Even with both functions, water may enter through seams or openings, so product design is also important.

Features

Waterproof and breathable materials are often used in clothing designed for comfort during activity because they help block rain and wind while reducing stuffiness. In structures using a membrane or film, the firmness, softness, stretch, and surface luster can differ greatly depending on the base fabric and processing method.

Even with a material that has moisture permeability, the amount of water vapor transfer varies depending on temperature, humidity, activity level, and layering conditions. Also, the presence of a waterproof layer may make breathability feel lower. Moisture permeability and breathability do not mean the same thing, so it is necessary to check according to the intended application.

Main Applications

It is often used for outerwear such as rainwear, mountain parkas, blousons, and coats. In sportswear, outdoor wear, and workwear, it is selected in combination with wind resistance, durability, and stretch, assuming use in rainy weather and perspiration.

For spring and summer, lightweight and thin constructions are used; for autumn and winter, constructions combined with insulation materials or linings are used. When used for bags or accessories, unlike apparel use, abrasion resistance and measures against water penetration from sewn areas are also considered.

Selection and Handling Notes

When selecting a textile, check not only waterproofness and moisture permeability, but also the abrasion resistance of the outer fabric, stretch, industry weight, stickiness on the back side, and the required washing durability. If you conduct wear tests and spray tests on prototypes including seams in conditions close to actual wearing conditions, it becomes easier to identify issues in the specifications.

When sewing waterproof and breathable textiles, needle holes can become a path for water intrusion. For products that require high waterproofness, consider treatments such as applying seam tape to the seams. Since heat from an iron or drying may affect the membrane or adhesive layer, check the handling conditions for each material.

During washing, if sebum or dirt remains on the surface, it may affect water repellency and the breathable feel. Whether fabric softener, bleach, strong friction, and high-temperature drying are allowed varies by product, so it is important to follow the care label and the textile manufacturer's handling information.

Differences from Similar Terms

Water-repellent processing is a treatment that makes water bead up and be repelled on the surface of the textile. Even with water repellency, water may penetrate under heavy rain or pressure. Waterproof, on the other hand, refers to the function of suppressing water intrusion, and waterproof and breathable adds the performance of letting water vapor escape more easily.

Lamination and bonding refer to processing and structures in which films, membranes, or other textiles are bonded together. This is one way to achieve waterproof and breathable performance, but not all laminated or bonded materials are waterproof and breathable.

Frequently Asked Questions

If it is a waterproof and breathable material, does water never enter through the seams?

Even if the textile itself is waterproof, water may enter through needle holes made during sewing, pockets, or zippers. If high waterproofness is required, as with rainwear, it is necessary to combine seam-tape treatment on the seams with auxiliary materials and specifications that take water resistance into account.

Which should I choose, waterproof and breathable or water-repellent processing?

If the main purpose is to repel light rain or provide light surface protection, water-repellent processing is an option. If you want to suppress rain intrusion and reduce stuffiness while wearing it, waterproof and breathable materials are suitable. However, the required performance should be judged by including the usage time, rainfall, activity level, and the product's sewing specifications.