question: Why do towels that are washed and then air dried end up so much rougher than ones that are tumble dried?
comment: The fibers stay clumped together and form little points when air drying, rather than being fluffed apart in the dryer.
passages: The wash durability of a calendared finish on thermoplastic fibers like polyester is higher than on cellulose fibers such as cotton. On blended fabrics such as Polyester/Cotton the durability depends largely on the proportion of synthetic fiber component present as well as the amount and type of finishing additives used and the machinery and process conditions employed.
  
  Section::::Variations.
  
  Several different finishes can be achieved through the calendering process by varying different parts. The main different types of finishes are "beetling", "watered", "embossing" and "Schreiner".
  
  Section::::Variations.:Beetled.
   An important and oldest textile finishing is brushing or raising. Using this process a wide variety of fabrics including blankets, flannelettes and industrial fabrics can be produced. The process of raising consists of lifting from the body of the fabric a layer of fibers which stands out from the surface which is termed as "pile". The formation of pile on a fabric results in a "lofty" handle and may also subdue the weave or pattern and color of the cloth.
   Such spinners generally buy their fibres pre-washed and carded, in the form of roving, sliver, or batts. This means less work for the spinners, as they do not have to wash out the lanolin. Spinners then have available predyed fibre, or blends of fibres, which are hard to create when the wool is still in the grease. As machine carders cannot card wool in the grease, pre-carded yarn generally is not spun in the grease. Some spinners use spray-on lanolin-like products to get the same feel of spinning in the grease with carded fibre. 
  
  Section::::See also.
  
  BULLET::::- Cotton mill
   BULLET::::- Non-slip finishes give the filaments a rougher surface. Synthetic warp and weft threads in loosely woven fabrics are particularly prone to slip because of their surface smoothness when the structure of fabric is disturbed and appearance is no longer attractive. Silica gel dispersions or silicic acid colloidal solutions are used in combination with latex polymer or acrylates dispersions to get more permanent effect, along with simultaneous improvement in resistance to pilling or snagging. These polymer finishes are also capable of imparting a soft and smooth handle to synthetic fabric without making it water repellent.
   Because it is carded, the fibres are less parallel than top (which is combed) and are not of uniform length. Carded rovings look fluffier than combed top, which looks smooth and has a high lustre. The fibres in combed top tend to be of a fairly uniform length due to the method of preparation. Though drawing it into strips may line the fibres up a bit. Roving is not to be confused with sliver as there is twist in roving.
   Section::::Combined equation for friction factor for all flow regimes.:Darby–Melson equation.
  
  In 1981, Darby and Melson, using the approach of Churchill and of Churchill and Usagi, developed an expression to get a single friction factor equation valid for all flow regimes:
  
  where:
  
  Both Swamee–Aggarwal equation and the Darby–Melson equation can be combined to give an explicit equation for determining the friction factor of Bingham plastic fluids in any regime. Relative roughness is not a parameter in any of the equations because the friction factor of Bingham plastic fluids is not sensitive to pipe roughness.
  
  Section::::See also.
  
  BULLET::::- Bagnold number
   BULLET::::- Water-based roller ball ink is more likely to smudge than a ballpoint pen's oil-based ink because water-based ink dries more slowly than its counterpart. Also if one writes in a notebook, closing it before the ink dries can stain the opposite page. This can also prove a problem for left-handed writers or users of right-to-left scripts. Gel ink dries much more rapidly than liquid-ink, making it much more, but not completely, resistant to smudging.
   The cast tape only dries from one side, the exposed surface, as the casting surface is impermeable. Drying is dependent on two processes, namely the evaporation of the solvent from the surface, and the diffusion of the solvent through the tape towards the single exposed surface. The evaporation may be sped up by applying air drying. However, usually evaporation should be limited to ensure steady diffusion of the solvent. If the solvent does not leave the sheet in a controlled fashion, the tape may crack or curl.
   Lay is the direction of the predominant surface pattern, ordinarily determined by the production method used. The term is also used to denote the winding direction of fibers and strands of a rope.
  
  Section::::Surface roughness.
  
  Surface roughness, commonly shortened to "roughness," is a measure of the total spaced surface irregularities. In engineering, this is what is usually meant by "surface finish." A Lower number constitutes less of these irregularities on the surface.
  
  Section::::Waviness.
   Section::::Construction breakdown.:2006.
   Recent studies have found a relationship between hydraulic roughness and salmon spawning habitat; “bed-surface grain size is responsive to hydraulic roughness caused by bank irregularities, bars, and wood debris… We find that wood debris plays an important role at our study sites, not only providing hydraulic roughness but also influencing pool spacing, frequency of textural patches, and the amplitude and wavelength of bank and bar topography and their consequent roughness. Channels with progressively greater hydraulic roughness have systematically finer bed surfaces, presumably due to reduced bed shear stress, resulting in lower channel competence and diminished bed load transport capacity, both of which promote textural fining”. Textural fining of stream beds can effect more than just salmon spawning habitats, “bar and wood roughness create a greater variety of textural patches, offering a range of aquatic habitats that may promote biologic diversity or be of use to specific animals at different life stages.”
   Calendering is the third important mechanical process, in which the fabric is passed between heated rollers to generate smooth, polished or embossed effects depending on roller surface properties and relative speeds.
  
  Section::::Finishing of cotton.:Finishing.:Chemical finishing.
  
  Many other chemical treatments may be applied to cotton fabrics to produce low flammability, crease resist and other special effects. 
  
  Section::::Finishing of cotton.:Finishing.:Shrinking.
  
  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.
  
  Section::::Standard finishes.
  
  Section::::Standard finishes.:Quality-oriented.
  
  BULLET::::- Calendering
  
  BULLET::::- Decatising
   In spinning, however, the yarn is continually issuing from the rollers of the drafting system and, under these circumstances, the angular velocity of the traveller is less than that of the spindle by an amount that is just sufficient to allow the yarn to be wound onto the bobbin at the same rate as that at which it issues from the drafting rollers. 
   Smoothness: Smoothness is particularly important when being used for printing, the smoother the paperboard, the better the image quality, because of better ink coverage. Smoothness is measured using air leak methods – the greater the rate of air leakage, at a specific air pressure, from under a cylindrical knife placed on the surface, the rougher the surface.
   Older surfaces, such as double jute-backed carpets and loose rugs with natural foundation yarns, could shrink after a wet treatment, leading to suppositions that wet-cleaning could also remove wrinkles. However, this notion is antiquated and this method could also occasionally tear seams or uproot strips. Newer carpets, such as with synthetic backing and foundation yarns, do not shrink, and they smooth easily; in such carpets, wrinkles indicate an underlying problem, such as delamination where the secondary backing becomes unstuck from the primary backing, that may need a certified carpet inspector to determine.
   Carding of wool can either be done "in the grease" or not, depending on the type of machine and on the spinner's preference. "In the grease" means that the lanolin that naturally comes with the wool has not been washed out, leaving the wool with a slightly greasy feel. The large drum carders do not tend to get along well with lanolin, so most commercial worsted and woollen mills wash the wool before carding. Hand carders (and small drum carders too, though the directions may not recommend it) can be used to card lanolin rich wool.
  
  Section::::Hand carding.:Drum carders.
   The quality and characteristics of mill finish can vary widely from one mill to another, and even from one lot (set of similar parts all processed consecutively or in a short time) to another. Hot rolled parts are usually dark and dull, their surface oxidized from being hot worked. Extruded products may have die marks running the length of the stock. Other mill finishes are surprisingly smooth and uniform. 
   BULLET::::- Anti-pilling finish alleviates pilling, an unpleasant phenomenon associated with spun yarn fabrics, especially when they contain synthetics. Synthetic fibers are more readily brought to the surface of a fabric due to their smooth surface and circular cross-section, and due to their higher tensile strength and abrasion resistance. With knit "picking" also occurs: by abrasion, individual fibers work themselves out of yarn loops onto the surface, and the garment catches on a pointed or rough object. Knitting is susceptible to these effects due to the open weave and bulky yarn.
   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.
   BULLET::::- Yarn realization in the case of waste mixing will be poor, resulting in increased mixing cost.
  
  BULLET::::- Wear and tear of rotors, combing rollers, and navels are very high when highly trash content mixing is used resulting in heavy replacement cost.
  
  BULLET::::- In case reeling is done additional reeling cost is involved resulting in higher manufacturing cost.
  
  Section::::Products.
  
  BULLET::::- Linen / Flax yarns
  
  BULLET::::- Cotton Yarns
  
  BULLET::::- Polyester Cotton Blended yarn
  
  BULLET::::- Tencel 100%
  
  BULLET::::- Polyester 100%
  
  BULLET::::- Polyester / Cotton / Linen / Viscose Multi blend
  
  BULLET::::- Dyed yarn (and fibre)
  
  BULLET::::- Acrylic
   Section::::Characteristics and methods of use.
   Before the introduction of automatic machinery, there was little difficulty in attaining a straight fibre, as long wool was always used, and the sliver was made up by hand, using combs. The introduction of Richard Arkwright's water frame in 1771, and the later introduction of cap and mule spinning machines, required perfectly prepared slivers. Many manufactories used one or more preparatory combing machines (called "gill-boxes") before worsting, to ensure straight fibres and to distribute the lubricant evenly.
  
  Section::::External links.
  
  BULLET::::- Standard Yarn Weight System - Lists recommended needle sizes, gauge, etc., for the various yarn weight categories.
   BULLET::::- Under certain circumstances, elimination of the second passage draw frame.
  
  BULLET::::- In some cases, with the use of auto-leveller at the cards, elimination of even the draw frame passage.
  
  BULLET::::- Bigger supply of cans to open-end and bigger packages to weaving.
  
  BULLET::::- Elimination of winding.
  
  BULLET::::- Less labor and power cost per kilogram of yarn.
  
  BULLET::::- Higher productivity almost 7 times in the case of 10s and high efficiency.
  
  BULLET::::- Fully automated mill a reality.
  
  Section::::Disadvantages.
  
  BULLET::::- Restricted only coarse counts.
  
  BULLET::::- High capital cost.
  
  BULLET::::- Usage restricted in case yarn is weak.
   The first open-end machines in the United Kingdom were placed, under great secrecy, by Courtaulds into Maple Mill, Oldham in 1967.
  
  One disadvantage of open-end spinning is that it is limited to coarser counts, another is the structure of the yarn itself with fibres less in parallel compared to ring-spun yarns, for example, consequently cloth made from open-end yarn has a "fuzzier" feel and poorer wear resistance.
  
  Section::::History.
   The fibre can be dyed at any time, but is often dyed before carding or after the yarn has been spun.
  
  Wool may be spun before or after washing, although excessive amounts of lanolin may make spinning difficult, especially when using a drop-spindle. Careless washing may cause felting. When done prior to spinning, this often leads to unusable wool fibre. In washing wool the key thing to avoid is too much agitation and fast temperature changes from hot to cold. Generally, washing is done lock by lock in warm water with dish-soap.
  
  Section::::Contemporary hand spinning.:Education.
  