question: How do t-shirts not have a seam along the torso when button up shirts do?
comment: The fabric is woven as a tube with the right diameter for that size of tshirt. This is only done with regular fit men's/unisex t-shirts as they are the same width all the way from chest to hem. With shirts, as well as slim fit and most fitted women's t-shirts they are made up of different shaped pieces that are sewn together to create curves that follow the contours of the body.
passages: Most Threadless T-shirts are printed with the screen printing technique. Plastisol or water based inks are applied to the shirt through mesh screens which limits the areas where ink is deposited. Threadless printing techniques include gradients and simulated process, UV color change, oversized printing, puff, belt printing, vinyl, super glow, flock, embroidery, suede, metallic, blister, foil, and high density.
  
  Section::::Printing techniques.:Direct to garment printing.
   Typically made of cotton textile in a stockinette or jersey knit, it has a distinctively pliable texture compared to shirts made of woven cloth. Some modern versions have a body made from a continuously knitted tube, produced on a circular knitting machine, such that the torso has no side seams. The manufacture of T-shirts has become highly automated and may include cutting fabric with a laser or a water jet.
  
  The T-shirt evolved from undergarments used in the 19th century and, in the mid-20th century, transitioned from undergarment to general-use casual clothing.
   BULLET::::- In couching, one or more threads are laid on the fabric surface and sewn to the fabric at regular intervals.
  
  BULLET::::- In couched filling, threads are laid on the surface in a trellis pattern and sewn to the fabric at the intersections.
  
  BULLET::::- In laid work or Bayeux stitch, threads are laid side-by-side to fill a shape, then held in place with a thread at right angles to the laid threads. This crossing thread is then couched to the fabric to hold the laid threads in place.
   A button-front shirt without a separate pieced placket is called a "French placket." The fabric is simply folded over and the buttonhole stitching secures the two layers (or three layers if there is an interlining). This method affords a very clean finish, especially if heavily patterned fabrics are being used. This method is normally only used in stiff-fronted formal evening ("white-tie") shirts. However, the normal, separate placket on a shirt gives a more symmetrical appearance.
   Basic knitted fabrics
  
  Basic knitted fabrics include stockinette stitch, reverse stockinette stitch, garter stitch, seed stitch, faggoting, and tricot. In some cases, these fabrics appear differently on the right side (as seen when making the stitch) than on the wrong side (as seen from the other side, when the work is turned).
  
  Section::::Stockinette/stocking stitch and reverse stockinette stitch.
   There are many types of ornamental embellishments that can modify the overall look of the sweater.
  
  Collars and lapels are perhaps the most visually obvious embellishments. They frame the face, neck and shoulders, and complement the neckline and armhole lines.
  
  The choice of closures is an important practical consideration and can also help define the sweater's style. Buttons and zippers are the most common choices for sweaters, but frogs, ties and belts are also seen.
  
  Shoulder pads and other shaping devices are uncommon, but can be included
  
  to define a particular silhouette.
   BULLET::::- In Underside couching, a heavy couching thread (historically, a stout linen) is brought up from the wrong side of the work, looped over the laid thread, and returned to the wrong side. The couching thread is then given a sharp pull which draws a small loop of laid thread through to the wrong side of the fabric. Underside couching has the advantages that the couching thread is completely concealed from the front and is not subject to wear.
  
  Section::::External links.
  
  BULLET::::- Illustration of underside couching
  
  BULLET::::- Chasuble in Opus Anglicanum, Metropolitan Museum of Art
  
  BULLET::::- Couching in Japanese embroidery
   BULLET::::- In Bokhara couching or Bokhara stitch, the couched threads are held in place with many tiny crossing stitches, which may be aligned from row to row to produce patterns.
  
  BULLET::::- In Roumanian stitch, long satin stitches are each held in place with a small diagonal stitch made in the center.
  
  BULLET::::- In Roumanian couching, bundles of laid threads are held in place with Roumanian stitches.
   BULLET::::- Front closures: Some garments are made with front closures, similar to fly openings on men's trousers and button plackets on men's shirts, but may retain a feminine cut. Other garments (such as uniform dresses for service workers like waitresses and cleaners, for example) may feature a front zipper, but concealed in a seam or flap of fabric.
  
  BULLET::::- Looser fit: A larger neckhole and/or a looser bodice allows the garment to be slipped on over the head without the need for a fastener.
   Since knitted fabric is generally elastic, it conforms readily to the wearer's body without shaping. However, some shaping may be necessary when the knitted fabrics are unusually stiff (e.g., thick cable designs or heavily overstitched designs) or in regions of high curvature (e.g. sock heels). Ironically, shaping is much easier and less obvious with knitted fabrics than with woven cloth. Instead of cutting out wedges and sewing the edges together, knitters can add or subtract stitches; work short rows; or, most subtly of all, change the needle size to produce smaller/larger stitches in the desired "wedge" region.
  
  Section::::Choosing the yarn.
   Because of the picked-up stitches, the back of stockinette entrelac is generally less attractive than the front, as seen in the photo to the left. 
  
  For garments and projects requiring square edges, the entrelac is ringed in triangles, knit in the same way as the squares but with increases and decreases. A row of triangles is the typical starting point for an entrelac project, though they can also be started with connected squares, as in the scarf to the left, which was knit from side to side starting with the white row.
   A bound seam has each of the raw edges of its seam allowances enclosed in a strip of fabric, lace or net 'binding' that has been folded in half lengthwise. An example of binding is double-fold bias tape. The binding's fold is wrapped around the raw edge of the seam allowance and is stitched, through all thicknesses, catching underside of binding in stitching.Bound seams are often used on lightweight fabrics including silk and chiffon and on unlined garments to produce a neat finish.
   Shuttle looms weave a narrower 30-inch fabric, which is on average half the width of modern shuttleless Sulzer looms. Consequently, a longer piece of fabric is required to make a pair of jeans from selvedge denim (approximately three yards).
  
  To maximize yield, most jeans are made from wide denim and have a straight outseam that utilizes the full width of the fabric, including the edges. Selvedge denim has come to be associated with premium quality jeans, which show the finished edges from the loom rather than the overlocked edges that are shown on other jeans.
  
  Section::::Dyeing.
   In a Hong Kong finish, a bias strip of fabric is cut to the width of the seam allowance plus 1/4". The bias strip is placed on top of the seam allowance, right sides together, and stitched 1/8" from raw edges. The bias strip is then folded over the raw edge and around to the underside and stitched in place.
  
  Section::::Position.
  
  In clothing construction, seams are identified by their position in the finished garment.
  
  A center front seam runs vertically down the front of a garment.
   In the simplest knitted fabric pattern, all the stitches are knit or purl; this is known as a garter stitch. Alternating rows of knit stitches and purl stitches produce what is known as a stockinette pattern/stocking stitch. Vertical stripes (ribbing) are possible by having alternating wales of knit and purl stitches. For example, a common choice is 2x2 ribbing, in which two wales of knit stitches are followed by two wales of purl stitches, etc. Horizontal striping (welting) is also possible, by alternating "rows" of knit and purl stitches. Checkerboard patterns (basketweave) are also possible, the smallest of which is known as "seed/moss stitch": the stitches alternate between knit and purl in every wale and along every row.
   Stitches can be worked from either side, and various patterns are created by mixing regular knit stitches with the "wrong side" stitches, known as purl stitches, either in columns (ribbing), rows (garter, welting), or more complex patterns. Each fabric has different properties: a garter stitch has much more vertical stretch, while ribbing stretches much more horizontally. Because of their front-back symmetry, these two fabrics have little curl, making them popular as edging, even when their stretch properties are not desired.
   A variety of fasteners are seen in fashion boots. Laces are commonly used in ankle boots, but are too time-consuming for longer styles. Zip fasteners are widely employed in all styles of boot – they may run the entire length of the shaft, or just the ankle and lower calf – these partial-length zips make it easier to insert the foot into the toe of the boot by relaxing the fit around the ankle. Pull-on boots have no fasteners and tend to have a looser fit than zip or lace-up boots; they sometimes have a loop of leather at the top of the shaft, called a boot-strap, to assist with pulling the boot on. Finally, button-fastened boots were common at the beginning of the last century but are rarely seen today. If present, buttons are usually employed as design accents on boots; other decorative features include straps, buckles, studs, and decorative stitching.
   In the bespoke (custom-made) industry where each shirt is made from an individually drafted pattern, these sizing problems are avoided, though there are still different ways of making the shirt fit. While many choose to cut the sleeve long and have the cuff catch on the hand to regulate its length, some prefer the much harder option of using a high armhole and carefully tailored shape, so that the cuff can be loose and still sit in exactly the right place wherever the arm moves.
   Knitted fabrics are generally somewhat elastic and have a softer hand (feel or drape) than woven fabric, sweaters that are more tightly fitted or have a soft drape may conform well to the body without requiring tailoring necessary in a woven garment such as darts, flares and gores. Even when such shaping is used, it can be knit into the fabric itself, without requiring seams.
  
  Another type is a sweater vest.
  
  Section::::Nomenclature.
   The base material can be a 2D-textile such as woven or non-woven fabric or a matrix-compatible foil material for thermoplastic composites. The stitching path can be designed in form of a pattern either with the help of classical design embroidery software or more recently by use of 2D-CAD systems. Afterwards necessary information of the stitch positions are added to the pattern with the help of so-called punch software and finally transferred to the TFP machine.
   Although the sleeve buttons usually cannot be undone, the stitching is such that it appears they could. Functional cuff buttons may be found on high-end or bespoke suits; this feature is called a "surgeon's cuff" or "working button holes" (U.S.). Some wearers leave these buttons undone to reveal that they can afford a bespoke suit, although it is proper to leave these buttons done up. Modern bespoke styles and high end off-the-rack suits equipped with surgeon's cuffs have the last two buttons stitched off-centre, so that the sleeve hangs more cleanly should the buttons ever be undone. Certainty in fitting sleeve length must be achieved, as once working button holes are cut, the sleeve length essentially cannot be altered further.
   The stitches that create the Aran knitting patterns are complex and the knitted goods are time-consuming to create. For example, a typical Aran sweater will have over 100,000 stitches, and may take several months to finish. The three dimensional effect of the twisted stitches also increased the warmth of the clothing by creating air pockets.
   In clothing construction, seams are classified by their "type" (plain, lapped, abutted, or French seams) and "position" in the finished garment (center back seam, inseam, side seam). Seams are "finished" with a variety of techniques to prevent raveling of raw fabric edges and to neaten the inside of garments.
  
  Section::::Types.
  
  All basics seams used in clothing construction are variants on four basic types of seams:
  
  BULLET::::- Plain seams
  
  BULLET::::- French seams
  
  BULLET::::- Flat or abutted seams
  
  BULLET::::- Lapped seams
   Warp-knit fabrics are resistant to runs and relatively easy to sew. Raschel lace—the most common type of machine made lace—is a warp knit fabric but using many more guide-bars (12+) than the usual machines which mostly have three or four bars. (14+)
  
  Section::::Structure of knitted fabrics.
  
  Section::::Structure of knitted fabrics.:Courses and wales.
   Modern stockings, pantyhose, and thigh highs are made by either flat knitting or the use of circular machines. Flat knitting is the original hosiery manufacturing technique of the 1930s–1950s. After the fabric has been produced, each thigh high is individually seamed. The top of the seam has a "finishing loop", a small hole that every seamed thigh high has as a result of the machinist turning the welt—the thigh high top—inside out, in order to finish off. Once sewn, the thigh highs are "boarded". This is a process where each thigh high is stretched over a flat metal leg form and "set" with steam. The knit tightens, creases are eliminated and the leg is correctly shaped. Because the process is time consuming, seamed thigh highs are never cheap. Also, around a third of production—especially during the production of sheer stockings—is discarded during quality control.
  