Waterproof fabric
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Waterproof fabrics are fabrics that are, inherently, or have been treated to become, resistant to penetration by water and wetting. The term "waterproof" refers to conformance to a governing
Definition and specifications
Waterproof/breathable fabrics resist liquid water passing through, but allow
Standard laboratory testing protocols [
One specific definition of "waterproof/breathable" requires the fabric to withstand a pressure of over 1,000 millimetres of water (9.8
These values should be taken with some caveats. Rain room tests show that some fabrics with less than 1,000 mm of water resistance keep water out sufficiently for practical purposes.[
Directional fabrics
Fabric construction which directs water away from the body, rather than membranes, coatings, or laminates, can be used to keep the wearer dry. This means that perspiration can be moved away from the body more effectively, as both liquid water and water vapour can be directed. These are directional fabrics such as Nikwax Analogy and FurTech, which are also breathable in the conventional sense (although these examples are actually a combination of two different fabrics, a directional "pump" layer underneath a distinct windproof and water-resistant outer layer; while effectively completely waterproof against rain, they would fail a strict hydrostatic head test as given in the definition above).
In combination with thermal insulation
Garments that combine waterproofing with some thermal insulation, such as those manufactured by FurTech and Nikwax Analogy, resist cold bridging, heat transferred through layers of poorly-thermally-insulating materials in close contact that would be prevented by a small airspace. When there is cold bridging, vapour on the dry side can condense on the cold surface, making it appear that the thin waterproof breathable fabric has leaked.
See also
- Durable water repellent
- Gore-Tex
- Hipora
- Layered clothing
- Nikwax Analogy
- Sauna suit
- Ventile
- Waterproofing
References
- ^ ASTM D3393-Standard Specification for Coated Fabrics – Waterproofness
- ^ "Water Vapour Transmission Rate Measurements". National Physical Laboratory. 1 June 2011. Archived from the original on 13 April 2014. Retrieved 23 May 2017.
External links
- "Breathability" comparison of commercial outerwear shell layers, Phil Gibson, 2000, United States Army Soldier Systems Center
- Water Resistant vs Waterproof – What's the Difference? Allthingswaterproof.com Article 2016