question: why do some clothes have an SPF rating?
comment: It is actually UPF. Some clothes are specifically designed so you don’t get sunburnt underneath your clothes. A white cotton t shirt won’t protect you from ultraviolet radiation. UPF clothing will.
passages: R Sayre was the lead researcher of "in vitro" SPF testing for regular summer fabrics. This revealed that traditional summer clothing in North America offered less than 15 SPF protection, the minimum level recommended by doctors. These regular summer fabrics tested between SPF 59 when dry and SPF 39 when wet. Nicholas Lowe and R Sayre followed this up with "in vivo" research. They found that Solumbra achieved over 50 SPF when dry or wet.
   The weight issue has been addressed by the production of Nikwax Analogy Light which uses a lighter windproof outer with the same Pump Liner fabric, resulting in garments that are 19-20% lighter than the same style made in standard Analogy fabric. Examples of these are the Velez Adventure Light Smock, the Quito Jacket, the Vista Jacket and the Velez Adventure Trousers.
   AATCC 183 should be used in conjunction with other related standards including ASTM D 6544 and ASTM D 6603. ASTM D 6544 specifies simulating the life cycle of a fabric so that a UPF test can be done near the end of the fabric's life, when it typically provides the least UV protection. ASTM D 6603 is a consumer format recommended for visible hangtag and care labeling of sun protective clothing and textiles. A manufacturer may publish a test result to a maximum of UPF 50+.
   Section::::Materials.:Non-iron.
  
  Wrinkle-free shirts have become popular after being first introduced by Brooks Brothers in 1953.
  
  A resin used for making non-wrinkle shirts releases formaldehyde, which could cause contact dermatitis for some people - particularly those who have already developed an allergy; no disclosure requirements exist, and in 2008 the U.S. Government Accountability Office tested formaldehyde in clothing and found that generally the highest levels were in non-wrinkle shirts and pants.
  
  Section::::Shirt wearing.
   A resin used for making non-wrinkle shirts releases formaldehyde, which could cause contact dermatitis for some people; no disclosure requirements exist, and in 2008 the U.S. Government Accountability Office tested formaldehyde in clothing and found that generally the highest levels were in non-wrinkle shirts and pants. In 1999, a study of the effect of washing on the formaldehyde levels found that after 6 months after washing, 7 of 27 shirts had levels in excess of 75 ppm, which is a safe limit for direct skin exposure.
  
  Section::::Life cycle.:Mending.
   Textile products can only be certified according to the "Standard 100 by Oeko-Tex" if all components comply with the required criteria – for an item of clothing, in addition to the outer fabric, this might include threads, linings, prints as well as non-textile accessories such as buttons, zip fasteners, rivets or any other accessory parts.
  
  Extent and requirements of Oeko-Tex testing for harmful substances depend on the intended use of a textile product. There are four product classes:
  
  BULLET::::- Product class I – Items for babies and infants (up to 36 months of age)
   In 1992, the FDA reviewed clothing that was being marketed with claims of sun protection (SPF, % UV blockage, or skin cancer prevention). Only one brand of sun protective clothing, Solumbra, was cleared under medical device regulations. The FDA initially regulated sun protective clothing as a medical device, but later transferred oversight for general sun protective clothing to the FTC. The UPF rating system may eventually be adopted by interested apparel/textile/fabric manufacturers as a "value added" program for consumer safety and awareness. Before UPF standards were in place (which directly measure a fabric's ability to block UV radiation), clothing was previously rated using SPF standards (which measure how long a person's skin takes to redden).
   In the United States labeling of wool products is regulated by the "Wool Products Labeling Act of 1939" (15 U.S.C. § 68). The Act was modified, for wool products manufactured on or after January 1, 2007, by the "Wool Suit Fabric Labeling Fairness and International Standards Conforming Act" which defined the use of the Super S and S designations in a manner conforming to the IWTO Code. The U.S. defines the S numbers for 80s to 250s. Violation of the WPLA may carry a substantial penalty.
  
  Section::::See also.
  
  BULLET::::- List of ISO standards
  
  BULLET::::- Spinning count
   Section::::Types of foundation garment.
   Both SFI and the FIA use the Thermal Protective Performance (TPP) test to measure the effectiveness of fire-retardant clothing. This test, created by DuPont in the 1970s, measures the amount of time in seconds before the wearer of a garment suffers second degree burns. For example, a garment that lasts three seconds before second degree burns occur receives a TPP value of 6. Under SFI standards, this would receive a rating of 3.2A/1, the lowest possible SFI rating.
  
  Section::::Design and use.:Non-fire retardant suits.
   The greater the pressure applied to the rubber sleeve during sanforization, the less shrinking will occur once the garment is in use. The process may be repeated.
  
  The aim of the process is a cloth which does not shrink significantly during production, cutting, ironing, sewing or, especially, by wearing and washing the finished clothes.
  
  Cloth and articles made from it may be labelled to have a specific shrink-proof value (if pre-shrunk), e.g., of under 1%.
  
  Section::::Applications.
   Numerous methods have been devised for evaluation of UVA and UVB protection. The most-reliable spectrophotochemical methods eliminate the subjective nature of grading erythema.
  
  The ultraviolet protection factor (UPF) is a similar scale developed for rating fabrics for sun protective clothing. According to recent testing by "Consumer Reports", UPF ~30+ is typical for protective fabrics, while UPF ~20 is typical for standard summer fabrics.
  
  Mathematically, the SPF (or the UPF) is calculated from measured data as:
   Below is the ASTM Standard for Sun Protective Clothing and Swimwear:
  
  According to recent testing by "Consumer Reports", UPF ~30+ is typical for protective fabrics, while UPF ~20 is typical for standard summer fabrics.
  
  Section::::UPF testing protocol.
  
  Developed in 1998 by Committee RA106, the testing standard for sun protective fabrics in the United States is the American Association of Textile Chemists and Colorists (AATCC) Test Method 183. This method is based on the original guidelines established in Australia in 1994.
   There is no formal definition of a superstrat; the categorisation is still largely left to popular opinion and depends greatly on the artist(s) associated with a particular model and how it is marketed.
  
  Section::::History.
  
  Section::::History.:Origin in custom modifications.
   Minus33 is claimed to have 100 years of textile manufacturing experience behind it in parent company L.W. Packard & Co. The company makes products primarily from superfine merino wool. Minus33 claims that this wool makes its products itch-free and resistant to shrinking. Minus33 also claims merino wool to have moisture wicking and antimicrobial properties, reducing odor. Reviews for Minus33 products are typically found in the context of equipment for hiking and other outdoor activities. Minus33 was featured on New Hampshire TV station WMUR channel 9 in January 2015, highlighting L. W. Packard & Co. Inc.'s 100 years of manufacturing contributions to the success of the company. In 2001, the history of L. W. Packard and startup of Minus33 was part of an interview on New Hampshire Public Radio.
   In November 2014 it was revealed that the £45 shirt in question was produced in a Mauritian factory where it was believed migrant workers from Bangladesh, Sri Lanka, India and Vietnam were paid less than a pound a day, slept 16 to a room, and otherwise kept in sweatshop conditions. The Fawcett Society responded with a press release stating, "We remain confident that we took every practicable and reasonable step to ensure that the range would be ethically produced and await a fuller understanding of the circumstances under which the garments were produced." Fawcett were assured by Whistles that their suppliers were "a fully audited, socially and ethical compliant factory which has the following accreditations".
   It is known that PVC clothes are made with a fabric covered with a plastic layer. For this reason, PVC clothes should not be over-stretched, to avoid damage to the plastic layer.
  
  When excessively stretching the clothing, the plastic layer can lose its smooth texture and stay striated, losing also part of the original shine, and may even tear.
   AATCC Test Method 135, Dimensional Change of Fabrics After Home Laundering
  
  Scope: Determines the dimensional changes of garments when subjected to home laundering procedures used by consumers. The method is for fabric not yet made into a garment. A sample is marked with benchmarks before home laundering. Then it is laundered 3 times total, then the benchmarks are measured again. Before and after laundering benchmarks are compared.
  
  AATCC Test Method 150, Dimensional Change of Fabrics After Home Laundering
  
  Scope: Determines the dimensional changes of garments when subjected to home laundering procedures used by consumers.
  
  Section::::Importance.
   The "Standard 100 by Oeko-Tex" is the product label for textiles tested for harmful substances with the largest prevalence worldwide. More than 10,000 manufacturers in almost 100 countries currently participate in Oeko-Tex certification. To date, the Oeko-Tex Association has issued over 160,000 "Standard 100" certificates for textile products from all stages of production (as of 12/2015).
   Made-to-measure shirts may not fit quite as well as bespoke, but can provide a similar degree of customisation and fit at a lower cost.
  
  For sixty years, US designers and manufacturers of neckties and dress shirts were members of the Men's Dress Furnishings Association but the trade group shut down in 2008 due to declining membership caused by the declining numbers of men wearing neckties.
  
  Section::::As part of dress codes.
   Section::::Fashion.:Negative.
   As sun protective clothing is usually meant to be worn during warm and humid weather, some UV-blocking textiles and clothing may be designed with ventilated weaves, moisture wicking and antibacterial properties to assist in cooling and breathability.
  
  UPF (Ultraviolet Protection Factor) represents the ratio of sunburn-causing UV without and with the protection of the fabric, similar to SPF (Sun Protection Factor) ratings for sunscreen. While standard summer fabrics have UPF ~6, sun protective clothing typically has UPF ~30, which means that only 1 out of ~30 units of UV will pass through (~3%).
  
  Section::::History.
   A factor of the two-fabric system is that it inevitably adds insulation, due to the requirement of the inner "pump" liner: being a fur substitute with a definite and designed structure it traps air as well as channeling water, which has an insulating effect. While this can be useful in cooler conditions it is less suitable for higher temperature and/or high activity conditions where overheating is more of a problem than an alternative which provides less insulation. Adding venting features to garments helps address this problem, but it is only a partial solution. 
   Section::::Background.
  
  There are three approaches for size-labelling of clothes:
  
  BULLET::::- Body dimensions: The label states the range of body measurements for which the product was designed. (For example: bike helmet label stating "head girth: 56–60 cm")
  
  BULLET::::- Product dimensions: The label states characteristic dimensions of the product. (For example: jeans label stating inner leg length of the jeans in centimetres or inches (not inner leg measurement of the intended wearer))
  
  BULLET::::- Ad hoc size: The label states a size number or code with no obvious relationship to any measurement. (For example: Size 12, XL)
   As part of revised guidelines for sunscreens in the EU, there is a requirement to provide the consumer with a minimum level of UVA protection in relation to the SPF. This should be a "UVA PF" of at least 1/3 of the SPF to carry the UVA seal.
  
  A set of final US FDA rules effective from summer 2012 defines the phrase "broad spectrum" as providing UVA protection proportional to the UVB protection, using a standardized testing method.
  
  Section::::Measurements of protection.:UVA protection.:Star rating system.
  
presuppositions: Clothes have SPF ratings. Some clothes have an SPF rating.
corrections: Clothes have UPF ratings, not SPF ratings. The correct rating that clothes are given are UPF and not SPF.
raw_presuppositions: Clothes have SPF ratings. Some clothes have an SPF rating. Some clothes have an SPF rating.
raw_corrections: Clothes have UPF ratings, not SPF ratings. The correct rating that clothes are given are UPF and not SPF. Some clothes have a UPF rating.