question: Why do items of clothing that you wear expand/loosen then revert back to normal after washing & drying?
comment: Depending in the temperature of water the coldness (or heat) of the water will make the fibers contract or expand. When your wearing clothes (unless your constantly in somewhere cold like living in a freezer or Antarctic your body temperature expells heat and thus warms your clothes and in turn expands the fibers
passages: Novice users of modern laundry machines sometimes experience accidental shrinkage of garments, especially when applying heat. For wool garments, this is due to scales on the fibers, which heat and agitation cause to stick together. In cold countries they dry it with their fireplaces, others just have many or buy more garments in preparation for winter or cold times. Other fabrics are stretched by mechanical forces during production, and can shrink slightly when heated (though to a lesser degree than wool). Some clothes are "pre-shrunk" to avoid this problem.
   Heat and humidity can both contribute and a textile’s deterioration. However, excessive dryness may also cause damage, especially to elastic fibers, such as wool, which rely on some amount of moisture to maintain their flexibility (Putnam and Finch). Additionally, temperature and humidity should be kept as constant as possible; changes in either of these may cause the textile fibers to expand and contract, which, over time, can also cause damage and deterioration to the textile. For this reason, both storage and display areas should be fitted with monitoring equipment to gauge the temperature and humidity of rooms, display cases, enclosed storage facilities, and work areas.
   There are various procedures to minimise the residual shrinkage of the fabrics,it begins with right selection of yarn count or denier to achieve particular g.s.m(Grams per square meters),Right selection of tightness factor of loops (which is called loop length then chemical procedures like mercerising of cotton,Resin of cotton in case of woven materials, Pre-heat-setting and post-heat setting of synthetic and blended fabrics( Heat setting is a thermal process taking place mostly in either a steam atmosphere or a dry heat environment. The effect of the process gives fibers, yarns or fabric dimensional stability). 
   Section::::Factors that determine the drying duration.
  
  Various factors determine the duration of drying and can help to decide rather to use a drier or a clothes line
  
  BULLET::::- The environmental temperature - increase of temperature decreases the drying duration
  
  BULLET::::- The environmental humidity - decrease of humidity will decrease the drying duration
  
  BULLET::::- Wind velocity - Sometimes people put a fan near the clothes when drying them indoors
  
  BULLET::::- Direct sun - usually only the external line will be exposed to direct sun, so usually people put the thickest clothes on the most external line.
  
  BULLET::::- Cloth thickness
   As with moving or working with dry pieces, the textile should be washed in a flat, fully supported position. Usually this is achieved through the use of screens like the ones used in vacuuming, though these may be supported in a frame of some kind for added stability. The textile should be sandwiched between two screens. If the piece is particularly delicate or fragile, it may be wrapped in netting, then placed between the screens. 
   Snags of this type (#3) may sometimes be repaired or minimized by firmly pressing with opposed finger and thumb at each end of the pulled thread (to prevent it from pulling further from each side), and gently pulling apart the bunched fabric, allowing the bunched fibers at the site of the snag to be drawn back in. Holding one end this way with one hand and using two fingers of the other hand on one side of the fabric (opposing the thumb on the other side) while slowly drawing them toward the snag site may also accomplish this. Any remaining fibres still protruding can then be trimmed off to keep them from snagging again.
   This factor also plays a vital role in the shrinking of the products. The products which are loosely woven or knitted are prone to shrink more and tightly knitted and woven products are more stable. The main reason is that knitted fabrics shrinkage is because they are made by interlooping the yarn which is comparatively a loose and flexible structure whereas woven are considered more stable and less sensitive to shrinkage.
  
  BULLET::::- Finishing applications and procedures
   Often, people wear an item of clothing until it falls apart. Some materials present problems. Cleaning leather is difficult, and bark cloth (tapa) cannot be washed without dissolving it. Owners may patch tears and rips, and brush off surface dirt, but materials like these inevitably age.
  
  However, most clothing consists of cloth, and most cloth can be laundered and mended (patching, darning, but compare felt).
  
  Section::::Life cycle.:Laundry, ironing, storage.
   The number of ends per inch in a piece of woven cloth varies depending on the stage of manufacture. Before the cloth is woven, the warp has a certain number of ends per inch, which is directly related to the size reed being used. After weaving, the number of ends per inch will increase, and it will increase again after being washed. This increase in the number of ends per inch (and picks per inch) and shrinkage in the size of the fabric is known as the take-up. The take-up is dependent on many factors, including the material and how tightly the cloth is woven. Tightly woven fabric shrinks more (and thus the number of ends per inch increases more) than loosely woven fabric, as do more elastic yarns and fibers.
   In preparation for calendering, the fabric is folded lengthwise with the front side, or face, inside, and stitched together along the edges. The fabric can be folded together at full width, however this is not done as often as it is more difficult. The fabric is then run through rollers that polish the surface and make the fabric smoother and more lustrous. High temperatures and pressure are used as well. Fabrics that go through the calendering process feel thin, glossy and papery.
   When the fabric is heated, the molecules are more easily reoriented. In the case of cotton fibres, which are derivatives of cellulose, the hydroxyl groups that crosslink the cellulose polymer chains are reformed at high temperatures, and become somewhat "locked in place" upon cooling the item. In permanent press pressed clothes, chemical agents such as dimethylol ethylene urea are added as crosslinking agents.
  
  Section::::Avoid.
  
  Avoid ironing can be obtained not using spin cycle in the washing machine.
  
  Section::::See also.
  
  BULLET::::- Domestic robot
  
  BULLET::::- Hair iron
  
  BULLET::::- Laundry symbol
  
  BULLET::::- Mangle (machine)
  
  BULLET::::- Ironing mannequin
  
  BULLET::::- Self-service laundry
  
  BULLET::::- Washing machine
   Non-polar solvents are also good for some fabrics, especially natural fabrics, as the solvent does not interact with any polar groups within the fabric. Water binds to these polar groups which results in the swelling and stretching of proteins within fibers during laundering. Also, the binding of water molecules interferes with weak attractions within the fiber, resulting in the loss of the fiber's original shape. After the laundry cycle, water molecules will dry off. However, the original shape of the fibers has already been distorted and this commonly results in shrinkage. Non-polar solvents prevent this interaction, protecting more delicate fabrics.
   Ideally, temperature should be kept around 70 degrees Fahrenheit, though some slight fluctuation in either direction is permissible, as long as it occurs gradually. For instance, temperature may be slightly lower in winter to save energy costs, but the change should be effected slowly, so as not to place the fibers under undue stress.
   Crease formation in woven or knitted fabric composed of cellulose during washing or folding is the main drawback of cotton fabrics. The molecular chains of the cotton fibers are attached with each other by weak hydrogen bonds. During washing or folding, the hydrogen bonds break easily and after drying new hydrogen bonds form with the chains in their new position and the creases are stabilized. If crosslinking between the polymer chains can be introduced by crosslinking chemicals, then it reinforces the cotton fibers and prevents the permanent displacement of the polymer chains when the fibers are stressed. It is therefore much more difficult for creases to form or for the fabric to shrink on washing.
   Section::::Types of shrinkage.
  
  Shrinkage is a change in dimensions across the length and width of the fabric after washing, usage and when exposed to relaxing of fabrics. Mainly shrinkage is of two types one is minus shrinkage and other is plus shrinkage. Skew (twisting of the vertical grains) is also observed along with shrinkage. Abnormal twisting is also considered as a non-conformity. 
  
  BULLET::::1. Contraction: Any noticeable decrease in dimensions is known as Contraction(minus) shrinkage.
  
  BULLET::::2. Expansion: Any noticeable increase or expansion in dimension is known as Expansion (plus) shrinkage.
  
  Section::::Causes.
  
  BULLET::::- Composition and properties of the fibres
   Finishing on machines like sanphorizing Mechanical shrinking (sometimes referred to as sanforizing), whereby the fabric is forced to shrink width and/or lengthwise, creates a fabric in which any residual tendency to shrink after subsequent laundering is minimal compacting machines. For wool garments, shrinkage is due to scales on the fibers which heat, water and agitation cause to stick together. Other fabrics are stretched by mechanical forces during production, and can shrink slightly when heated (though to a lesser degree than wool). Some clothes are shrunk in the factory to avoid this problem.
  
  Section::::See also.
  
  BULLET::::- List of laundry topics
   Machine washing puts great mechanical stress on textiles, particularly natural fibers such as cotton and wool. The fibers at the fabric surface are squashed and frayed, and this condition hardens while drying the laundry in air, giving the laundry a harsh feel. Adding a liquid fabric softener to the final rinse (rinse-cycle softener) results in laundry that feels softer.
   Many kinds of clothing are designed to be ironed before they are worn to remove wrinkles. Most modern formal and semi-formal clothing is in this category (for example, dress shirts and suits). Ironed clothes are believed to look clean, fresh, and neat. Much contemporary casual clothing is made of knit materials that do not readily wrinkle, and do not require ironing. Some clothing is permanent press, having been treated with a coating (such as polytetrafluoroethylene) that suppresses wrinkles and creates a smooth appearance without ironing.
   Steaming and ironing textiles should be done with caution, as the heat may affect the viability of the fibres. More importantly, the fabric should always be cleaned before either of these processes is used, since heat may trap dirt and stains in the fibres to such an extent that the stain becomes permanent. Always use the lowest setting for either of these procedures. If a garment relies on folds to maintain its proper shape (such as pleats), it may be better to finger-press the folds into place when the garment is damp and allow it to dry that way, rather than subject it to the added stress of ironing.
   Section::::Desizing processes.
  
  Desizing, irrespective of what the desizing agent is, involves impregnation of the fabric with the desizing agent, allowing the desizing agent to degrade or solubilise the size material, and finally to wash out the degradation products. The major desizing processes are:
  
  BULLET::::- Enzymatic desizing of starches on cotton fabrics
  
  BULLET::::- Oxidative desizing
  
  BULLET::::- Acid desizing
  
  BULLET::::- Removal of water-soluble sizes
  
  BULLET::::- Fermentative desizing
  
  Section::::Desizing processes.:Enzymatic desizing.
   Indeed, it is found that the laundry enzyme has a side effect on the cloth made from delicate materials. According to the test, untreated knit and woolen fabrics were soaked in a solution with household laundry enzyme formulation. Other variables, time and temperature up to 10 days and 40℃ respectively, were kept constant. As a result, it was found that the loss in strength was proportional to both soaking time and the laundry enzyme concentration and these materials were weakened also to some extent. The loss was also accompanying with reduced mass and the relationship between the loss and soaking time was linearly logarithmic, suggesting laundry enzymes would damage the fragile textile if soaking in a long time
   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.
   Textile stabilization
  
  Textile stabilization is a conservation method used to stabilize weak points in textile pieces and prevent further degradation or damage to the fabric. 
  
  Section::::Methods.
  
  Section::::Methods.:Localized and Overall Support.
  
  Fabric may be used to provide support for the garment by stabilizing weak sections or by creating a backing or lining for the piece. Darning may be utilized on coarsely-woven fabrics with localized areas of damage. 
  
  Section::::Methods.:Localized and Overall Support.:Fabric Properties.
  
  BULLET::::- Should not cause damage through friction with the original fabric
  
  BULLET::::- Be of similar or lighter weight than the original fabric.
   Fibres to fabric conversion implies lots of mechanical tensions and forces during manufacturing, which includes following steps for fibre to yarn conversion with spinning then fabric with weaving, knitting.
  
  Section::::Test methods.
  
  The different test methods are used as per the final destination of the product (Europe, U.S.A., etc) and the expected washing or laundry methods in practice. Mainly I.S.O. and AATCC standards are used for shrinkage testing. There are few brands which are customizing the test method as per their quality norms.
  
  Test Method(s):
  
  BULLET::::- AATCC Test Method 135
  
  BULLET::::- AATCC Test Method 150
  
  BULLET::::- ISO 6330
  
  BULLET::::- CAN/CGSB 58
   When working with the textiles, it should be placed on a clean, flat surface which is larger than the textile itself, so that the whole piece is supported evenly. Although it is supported, never place anything on top of the textile while it is in the flat position.
  