Saturday, December 3, 2016

The Three Basic Weaves - Twill Weave [1]
Art Resource

Marie-Therese Wisniowski

Preamble
This is the fifty-nineth post in the "Art Resource" series, specifically aimed to construct an appropriate knowledge base in order to develop an artistic voice in ArtCloth.

Other posts in this series are:
Glossary of Terms
Units Used in Dyeing and Printing of Fabrics
Occupational, Health & Safety
A Brief History of Color
The Nature of Color
Psychology of Color
Color Schemes
The Naming of Colors
The Munsell Color Classification System
Methuen Color Index and Classification System
The CIE System
Pantone - A Modern Color Classification System
Optical Properties of Fiber Materials
General Properties of Fiber Polymers and Fibers - Part I
General Properties of Fiber Polymers and Fibers - Part II
General Properties of Fiber Polymers and Fibers - Part III
General Properties of Fiber Polymers and Fibers - Part IV
General Properties of Fiber Polymers and Fibers - Part V
Protein Fibers - Wool
Protein Fibers - Speciality Hair Fibers
Protein Fibers - Silk
Protein Fibers - Wool versus Silk
Timelines of Fabrics, Dyes and Other Stuff
Cellulosic Fibers (Natural) - Cotton
Cellulosic Fibers (Natural) - Linen
Other Natural Cellulosic Fibers
General Overview of Man-Made Fibers
Man-Made Cellulosic Fibers - Viscose
Man-Made Cellulosic Fibers - Esters
Man-Made Synthetic Fibers - Nylon
Man-Made Synthetic Fibers - Polyester
Man-Made Synthetic Fibers - Acrylic and Modacrylic
Man-Made Synthetic Fibers - Olefins
Man-Made Synthetic Fibers - Elastomers
Man-Made Synthetic Fibers - Mineral Fibers
Man Made Fibers - Other Textile Fibers
Fiber Blends
From Fiber to Yarn: Overview - Part I
From Fiber to Yarn: Overview - Part II
Melt-Spun Fibers
Characteristics of Filament Yarn
Yarn Classification
Direct Spun Yarns
Textured Filament Yarns
Fabric Construction - Felt
Fabric Construction - Nonwoven fabrics
A Fashion Data Base
Fabric Construction - Leather
Fabric Construction - Films
Glossary of Colors, Dyes, Inks, Pigments and Resins
Fabric Construction – Foams and Poromeric Material
Knitting
Hosiery
Glossary of Fabrics, Fibers, Finishes, Garments and Yarns
Weaving and the Loom
Similarities and Differences in Woven Fabrics
The Three Basic Weaves - Plain Weave (Part I)
The Three Basic Weaves - Plain Weave (Part II)

The Glossary of Terms, Timelines, A Fashion Data Base, Glossary of Colors, Dyes, Inks, Pigments and Resins and Glossary of Fabrics, Fibers, Finishes, Garments and Yarns have been updated in order to better inform our art practice.

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Twill Weave
Twill weave is one in which each warp or filling (weft) yarns floats across two or more filling or warp yarns with a progression of interlacings by one to the left or right to form a distinct diagonal wale (i.e. a ridge on a textured woven fabric such as corduroy). A float is that portion of a yarn which crosses over two or more yarns from opposite direction.

Twill weave fabric.

Twill weave varies in the number of harnesses used. The simplest twill requires three harnesses. The more complex twills may have as many as 15 to 18 harnesses and are woven on loom with a dobby attachment. Note: on a loom, a harness is the frame containing heddles through which the warp is drawn and which, in combination with another such frame or other frames, forms the shed that determines the woven pattern.

A twill weave blanket which was created using 8 harnesses and 10 treadles.

Twill weave is often designated by a fraction (for example, 2/1) in which the numerator indicates the number of harnesses that are raised and the denominator indicates the number of harnesses that are lowered when a filling yarn is inserted. The fraction 2/1 would be read as “two up, one down”. A 2/1 twill is shown in the figure below. The floats on the surface are the warp yarns, making it a warp surface or warp-faced twill.

Top: Schematic of a 2/1 twill weave. Bottom: Twill weave fabric – three-harnesses 2/1.

Characteristics
All twill fabrics are characterized by diagonal wales which vary in prominence, direction and degree of angle.

The prominence of a twill wale may be increased by the use of long floats, combed yarns, ply yarns, hard-twist yarns, twist of yarns opposite to the direction of the twill line and by use of high thread counts. Fabrics with prominent wales such as gabardine may become shiny because of flattening due to the pressure of wear.

A cotton gabardine trench coat with facing panels and a detachable warmer in soft wool cashmere.

If the ridges have been flattened by pressure, steaming will raise them to remove the shine. Pure white vinegar (5%) or sandpaper may be removed to remove shine caused by either pressure or wear. Dip a piece of terry cloth in the vinegar, wring it out and rub hard and fast in the both directions of the cloth in the shiny area. As the cloth dries the odor will disappear. Do not iron or press, as either process may flatten the ridges again. Use sandpaper with a gentle rubbing motion.

The direction of a twill wale usually goes from lower left to upper right in wool and wool-like fabrics – right-hand twills – and from lower right to upper left in cotton or cotton like fabrics – left-hand twills.

Twill fabric is also woven in two different directions: a left handed or S twill (figure A above) and a right handed or Z twill (figure B above).

Left hand twill is also known as “S twill” and right hand twill is also known as “Z twill”. Right hand twill is known to have a flatter and smoother surface compared to other twill fabrics.

The facts above are only important in deciding which is the right and wrong side of a twill fabric. In some fabrics that have a very prominent wale or are made with white and colored yarns, the two lapels of a coat or suit will not look the same (see figure below).

Twill wales in lapel look unbalanced. This cannot be avoided and if it is disturbing, a garment of different design should be chosen.

The degree of angle of the wale depends on the balance of the cloth. The twill line may be steep, regular or reclining.

Twill angle steeper than the ideal angle of 45 degree.

The greater the difference between the number of warp and filling yarns, the steeper the twill line will be. Steep twill fabrics have a high warp count and therefore are stronger in the warp direction. The importance of the angle is that it serves as a guide in determining the strength of the fabric. The diagram below shows how the twill angle changes in steepness when the number of warp yarns changes and the filling yarns remain the same in number.

Twill angle depends on the ratio of warp to filling.

Twill fabrics have a number of common characteristics. They have a right and wrong side. If there are warp floats on the right side, there will be filling floats on the wrong side. If the twill wale does up to the right on one side, it will go up to the left on the other side. Twill fabrics have no up-and-down. Check this fact by turning the fabric upside down and then examine the direction of the twill wale.

Face.

Back.

Sheer fabrics are seldom made with a twill weave. Printed designs are seldom used, except in silk and lightweight twills because a twill surface has an interesting texture and design. Soil shows less on the uneven surface f twills than it does on smooth surfaces.

Sheer Panel Sleeve twill circle dress.

Fewer interlacing give the fabric more softness, pliability and wrinkle recovery than a comparable plain weave fabric would have because the yarns can now move more freely. When there are fewer interlacings, yarns can be packed closer together to produce a higher count fabric with more weight and durability. If a plain weave fabric and a twill weave fabric had the same kind and number of yarns, the plain weave fabric would be stronger because of interlacings.


Classification of Twill Fabrics
Twill weave fabrics are classified according to the kind of yarn exposed on the surface, as even-sided twills and filling lace twills. Note: Filling-faced twills are not discussed in this section since they are seldom used. They are usually reclining twills.

Examples of even-sided twills.

Even-Sided Twills
Even-sided twills have the same amount of warp and filling yarn exposed on both sides of the fabric. They are sometimes called reversible twills because they look alike on both sides, although thre direction of the twill line differs. Better quality filling yarns must be used in these fabrics than in warp-faced twills since both sets of yarns are exposed to wear. They are 2/2 twills and have the best balance of all twill weaves.

Reversible twill 2/2 – even-sided. Notice change of warp and filling. Notice change of warp and filling. Warp yarns are dark to correspond the checkerboard design.

Serge is a 2/2 twill with a rather subdued wale, which is still quite apparent. Cotton serge of fine yarn, high count is often given a water-repellent finish and used for jackets, snow suits and raincoats. Heavy yarn cotton serge is used for work pants. Wool serge gets shiny from abrasions and repeated pressing but is not the subject to flattening of the wale as gabardine. Luster comes from the smoothness of yarns. Good quality wool serge is made of fine fiber, two ply worsted yarns and has a high thread count. Serge comes in various weights.

Dress: 1806-1810, twill-weave silk and silk serge.

Twill flannel is similar to serge in construction but differs in appearance. Flannel has a napped surface, which gives it a soft fuzzy appearance. The filling yarns are low-twist, larger yarns specially made for napping. Some flannels has a 2/1 construction. Flannels may be either woolen or worsted. Worsted flannels, frequently used in tailored suits, are easy to press and will take and hold a sharp crease. They usually have less nap than woolen flannels and are less apt to show wear at the edges of the sleeves and elbows. Low-count flannels will tend to get “baggy” in areas of stress because there are fewer points of contact between fibers in low-twist yarns. The fibers tend to pull past one another when there is tension in the fabric.

Brushed worsted wool flannel suit.

Surah is a printed filament twill fabric of 2/2 construction, which is used in silk-like dresses, linings, ties and scarves.

Surah is a soft, lightweight lustrous silk characterized by fine twill lines. Because it isn’t durable, it’s best used in ties and vest fronts.

Warp-Faced Twills
Warp-faced twills have a prominence of warp yarns on the right side of the cloth. Since warp yarns are made with higher twist, they are stronger and more resistant to abrasion; thus, they should be more durable than comparable filling-faced fabrics. They are widely used in utility garments.

Twill 2/1 – warped-faced.

Examples of warp-faced twills.

Drill is a fairly heavy cotton fabric used for work clothing, uniforms and ticking. It is piece dyed. It also has many uses in the unfinished, gray-goods state. For example, it makes good ironing board covers.

Cotton drill (cotton twill).

Jean is lighter in weight than drill. It is used for children’s play clothes, draperies, slipcovers, and work shirts. Jean is not heavy enough for work pants.

Jean fabric – light green floral print.

Denim is a yarn dyed fabric that comes in two weights. Overall denim is made of heavier yarns than drill and usually has blue yarns in the warp and natural yrns in the filling. Sportswear denim is similar to drill in weight and may have stripes, plaids or to appear a solid color. It is used in sports ware, slipcovers and the like. Blue jeans, Levi and Levi Strauss for example, and dungarees and overalls are made from denim; the name refers to the cut of trousers. Fashion fabrics in denim may be napped, over printed or figured.

Embroidered denim jeans.

Gabardine is a warp-faced steep twill with very prominent distinct wale. It has a 63o angle or greater and always has more warp than filling. Cotton gabardine is made with 11, 13 or 15 harnesses. Long floats, which make the diagonal lines, are combined with short floats between the wales. Cotton gabardine is used for slacks and shorts, wind-repellent jackets and raincoats. Rayon and wool gabardine are sometimes made with a three-harness arrangement in which the warp yarns are crowded close together, giving a steep twill.

Vintage rayon gabardine cowboy jacket and shirt.

Herringbone Fabric
Herringbone fabrics have the twill line reversed at regular intervals to give a design that resembles the backbone of a fish. These may be steep or regular twills and the twill lines may be equally prominent or one side may be more subdued.

Dark grey Herringbone jacket.


Reference:
[1] N. Hollen and J. Saddler, Textiles, 3rd Edition, MacMillan Company, London (1968).