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 specification[1] and specific conditions of a laboratory test method. They are usually natural or synthetic fabrics that are laminated to or coated with a waterproofing material such as rubber, polyvinyl chloride (PVC), polyurethane (PU), silicone elastomer, fluoropolymers, and wax. Treatment could be either of the fabric during manufacture or of completed products after manufacture, for instance by a waterproofing spray. Examples include the rubberised fabric used in Mackintosh jackets, sauna suits and inflatable boats.
The most common waterproofing treatment in the early 2000s was the application of C8 fluorocarbon-based textile finishes during manufacture. However, environmental and health concerns led to a transition to C6 fluorocarbon-based finishes and the development of alternative chemistries, such as ChemStik technology, a solvent-free process involving the on-surface polymerization of hydrocarbon chains.[2]
Definition and specifications
Waterproof/breathable fabrics resist liquid water passing through, but allow water vapour to pass through. Their ability to block out rain and snow while allowing vapour from sweat to evaporate leads to their use in rainwear, waterproof outdoor sports clothing, tents, and other applications.
Standard laboratory testing protocols[which?] define the performance of these fabrics. Water resistance is measured by the amount of water, in mm, which can be suspended above the fabric before water seeps through.[citation needed] Breathability or Moisture vapor transmission rate is measured by the rate at which water vapor passes through, in grams of water vapour per square meter of fabric per 24-hour period (g/m2/d),[3] often abbreviated to just "g". In recent years [timeframe?] some,[who?] but not all, sporting goods manufacturers have begun including this information on their product labels. Typical mid-range fabrics tend to have values of 5,000 mm of water resistance and 5,000 g of breathability; the best materials have 20,000 mm and 20,000 g.
One specific definition of "waterproof/breathable" requires the fabric to withstand a pressure of over 1,000 millimetres of water (9.8 kPa) pressure without leaking (see hydrostatic head).[citation needed]
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.[citation needed] Garments made from these fabrics tested in the Leeds University Rain Room show no signs of leakage after 4 hours of simulated rain five times heavier than heavy rain.[clarification needed] However, some garments made from fabrics that exceed 20 000 mm have leaked through zips, hoods, and seams. Fabric head ratings do not totally specify water resistance of a garment, as it does not test closures such as zips. In addition, the breathability of nearly all waterproof/breathable fabrics is very dependent upon weather conditions, especially temperature, humidity and wind.[according to whom?]
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, and 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
Layered clothing
Sauna suit
Waterproofing
Hipora
Gore-Tex
Ventile
Nikwax Analogy
D'decor
Natural rubber, also called India rubber or caoutchouc, as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds, plus water. Malaysia and Indonesia are two of the leading rubber producers. Forms of polyisoprene that are used as natural rubbers are classified as elastomers.
Currently, rubber is harvested mainly in the form of the latex from the rubber tree or others. The latex is a sticky, milky colloid drawn off by making incisions in the bark and collecting the fluid in vessels in a process called "tapping". The latex then is refined into rubber ready for commercial processing. In major areas, latex is allowed to coagulate in the collection cup. The coagulated lumps are collected and processed into dry forms for marketing.
Natural rubber is used extensively in many applications and products, either alone or in combination with other materials. In most of its useful forms, it has a large stretch ratio and high resilience, and is extremely waterproof.[1]
History
The first use of rubber was by the indigenous cultures of Mesoamerica. The earliest archeological evidence of the use of natural latex from the Hevea tree comes from the Olmec culture, in which rubber was first used for making balls for the Mesoamerican ballgame. Rubber was later used by the Maya and Aztec cultures - in addition to making balls Aztecs used rubber for other purposes such as making containers and to make textiles waterproof by impregnating them with the latex sap.[6][7]
The Pará rubber tree is indigenous to South America. Charles Marie de La Condamine is credited with introducing samples of rubber to the Académie Royale des Sciences of France in 1736.[8] In 1751, he presented a paper by François Fresneau to the Académie (published in 1755) that described many of rubber's properties. This has been referred to as the first scientific paper on rubber.[8] In England, Joseph Priestley, in 1770, observed that a piece of the material was extremely good for rubbing off pencil marks on paper, hence the name "rubber". It slowly made its way around England. In 1764 François Fresnau discovered that turpentine was a rubber solvent. Giovanni Fabbroni is credited with the discovery of naphtha as a rubber solvent in 1779.
South America remained the main source of the limited amounts of latex rubber used during much of the 19th century. The trade was heavily protected and exporting seeds from Brazil was a capital offense, although no law prohibited it. Nevertheless, in 1876, Henry Wickham smuggled 70,000 Pará rubber tree seeds from Brazil and delivered them to Kew Gardens, England. Only 2,400 of these germinated. Seedlings were then sent to India, British Ceylon (Sri Lanka), Dutch East Indies (Indonesia), Singapore, and British Malaya. Malaya (now Peninsular Malaysia) was later to become the biggest producer of rubber.
In the early 1900s, the Congo Free State in Africa was also a significant source of natural rubber latex, mostly gathered by forced labor. King Leopold II's colonial state brutally enforced production quotas. Tactics to enforce the rubber quotas included removing the hands of victims to prove they had been killed. Soldiers often came back from raids with baskets full of chopped-off hands. Villages that resisted were razed to encourage better compliance locally.[9] See Atrocities in the Congo Free State for more information on the rubber trade in the Congo Free State in the late 1800s and early 1900s. Liberia and Nigeria started production.
In India, commercial cultivation was introduced by British planters, although the experimental efforts to grow rubber on a commercial scale were initiated as early as 1873 at the Calcutta Botanical Gardens. The first commercial Hevea plantations were established at Thattekadu in Kerala in 1902. In later years the plantation expanded to Karnataka, Tamil Nadu and the Andaman and Nicobar Islands of India. India today is the world's 3rd largest producer and 4th largest consumer.[10]
In Singapore and Malaya, commercial production was heavily promoted by Sir Henry Nicholas Ridley, who served as the first Scientific Director of the Singapore Botanic Gardens from 1888 to 1911. He distributed rubber seeds to many planters and developed the first technique for tapping trees for latex without causing serious harm to the tree.[11] Because of his fervent promotion of this crop, he is popularly remembered by the nickname "Mad Ridley".[12]
Pre-World War II
Charles Goodyear developed vulcanization in 1839, although Mesoamericans used stabilized rubber for balls and other objects as early as 1600 BC.[13][14]
Before World War II significant uses included door and window profiles, hoses, belts, gaskets, matting, flooring and dampeners (antivibration mounts) for the automotive industry. The use of rubber in car tires (initially solid rather than pneumatic) in particular consumed a significant amount of rubber. Gloves (medical, household and industrial) and toy balloons were large consumers of rubber, although the type of rubber used is concentrated latex. Significant tonnage of rubber was used as adhesives in many manufacturing industries and products, although the two most noticeable were the paper and the carpet industries. Rubber was commonly used to make rubber bands and pencil erasers.
Rubber produced as a fiber, sometimes called 'elastic', had significant value to the textile industry because of its excellent elongation and recovery properties. For these purposes, manufactured rubber fiber was made as either an extruded round fiber or rectangular fibers cut into strips from extruded film. Because of its low dye acceptance, feel and appearance, the rubber fiber was either covered by yarn of another fiber or directly woven with other yarns into the fabric. Rubber yarns were used in foundation garments. While rubber is still used in textile manufacturing, its low tenacity limits its use in lightweight garments because latex lacks resistance to oxidizing agents and is damaged by aging, sunlight, oil and perspiration. The textile industry turned to neoprene (polymer of chloroprene), a type of synthetic rubber, as well as another more commonly used elastomer fiber, spandex (also known as elastane), because of their superiority to rubber in both strength and durability.