Ventile, is a registered trademark used to brand a special high-quality woven cotton fabric first developed by scientists at the Shirley Institute in Manchester, England. Originally created to overcome a shortage of flax used for fire hoses and water buckets, its properties were also useful for pilots' immersion suits, but expensive and leaky if exposed to sweat or oils.
Extra-long-staple (ELS) cotton fibres are used to form a low-twist yarn, which is then woven into a tight high-density textile to create a 100% cotton fabric, capable of providing an effective barrier against inclement weather. In wet weather the softly spun yarns - within the tight weave - dynamically expand to form an effective barrier against the elements.
Currently the only manufacturer of this specification of cotton textile is the Swiss firm Stotz & Co AG, which spins, twists, weaves and dyes the raw materials, and sells the textile directly under its own branding of etaProof cotton, supplying clothing manufacturers and wholesale textile distributors globally.
British production of Ventile eventually ended in the late 20th century but the trademark continued to be used by the British company Talbot Weaving (Chorley) Limited to market their wholesale distribution of etaProof cotton fabrics until 2017 when the trademark ownership was transferred to the manufacturer Stotz & Co AG. Alternative registered trademarks, owned by other commercial organisations used to market, promote or distribute the fabric, include Supermarine and Duuton3.
The cotton textile is densely woven from an extra long staple fibre (ELS). Although weatherproof, it is not coated or laminated; the combination of a dense weave and the swelling of the fibres when wet provide excellent weatherproofing. ELS cotton fibres are only available from around 2% of the world's entire cotton crop, but due to their naturally long length this creates yarns of superior strength as they can be spun using an exceptionally low twist. The natural product offers a high level of comfort due to its drape and breathability, while being durable and quiet in use. It also has good resistance to tearing and burning. However, it is not as light in weight as synthetic fabrics, particularly when wet. While only fabrics scoring hydrostatic head measurements of 1000mm or more are technically considered to be fully waterproof, etaProof fabrics (200g to 270g standard versions) achieve measurements no less than 750mm. This is usually considered to be sufficient for reasonable protection against typical rain. The standard 300g version scores 900mm, and the UK Ministry of Defence considers a measurement of 800mm to be "waterproof". A common design feature of some Ventile overgarments uses two separate layers of the textile - with offset seams - to dramatically improve the garment's weatherproof protection. This is commonly called double-layer or twin-layer Ventile.
|Breaking strength: warp minimum(N/5 cm)||1000||1100||1200||1400||1200||1500|
|Breaking strength: weft minimum(N/5 cm)||650||750||1000||1400|
|Tear strength: warp minimum(g)||900||1200||1350||1800||2200|
|Tear strength: weft minimum(g)||650||750||800||1200||1600|
|Impregnation of DWR||Dendrimer based (until 2021 was fluorocarbon-6)|
|Water absorption(max. %)||10|
|Resistance to water hydrostatic head(mm)||750||600||750||900|
L24/5620 and L19/5610 are made also in Organic way, denominated 5620.1 RUC and 5610.1 RUC respectively, replacing the fluorocarbon of DWR with paraffin wax. With this change, three properties worsened: Water absorption changed from 10% to 15%, Resistance to water hydrostatic head changed from 750mm to 600mm and Oil repellency changed from 5–6 to 0.
Fabrics made from the material are used in outerwear performance garments and have military, medical and workwear applications.
Ventile is still used in military uniforms, especially for pilots flying over water. It is not often used in the United States, but in Europe, especially in the UK, it has had a revival with the bushcraft movement. It is popular with birdwatchers and naturalists because, unlike synthetic fabrics such as Gore-Tex, it is quiet in use. Alternative branding of the textile, such as Duuton3, is designed to promote less emphasis upon waterproofing and to disassociate itself from the reserve of military, vintage or bushcraft use and position its adoption more favourably amidst travel-wear, general outdoor sports and functional fashion as a practical cotton material with coincidental weatherproof characteristics.
[F]rom 1951, the Mk 7 onwards was made from ventile fabric, invented by the Shirley Institute just post war. [I]t was woven from Egyptian cotton in [a way that] would allow body moisture (i.e. water vapour) to pass through the interstices of the fabric, yet when immersed, the cotton fibres would swell to produce a waterproof garment. [S]uits had to be made from two layers of fabric to prevent the hydrostatic force of the water pushing its way through a single layer of fabric before the fabric had time to swell (Reference 172). Other disappointments were that it was very expensive to manufacture, expensive and labour intensive to construct the suits, and the fibres would not swell effectively when exposed to body sweat or greases.