Tuesday, 17 May 2011

What Way to Go? Weft or Warp?

A few things you must always remember are your wovens, knits and non-wovens. These can get very tricky, but they're really very simple!

 Firstly, these are your beloved weaves. Now, it is very simple to remember your Weft and Warp Yarns. Think of it like this:
Weft = Left, Warp = Vertical
All you need to remember is that the weft yarn goes to the left, over and under the warp yarns, if you remember that then you can simply figure it out by process of elimination. The bias-strip goes diagonally across the fabric.

The Plain Weave is a classic chessboard weave, it is the simplest of them all and produces a very basic woven effect. It can cause a garment to be easily torn and wrinkled. It is the most used weave construction and can provide endless design variations when incorporating plain, thick and thin, fancy and coloured yarns. The weave is strong, firm and hardwearing.
The Satin Weave is quite strong, more absobent than the plain weave. It is warp faced (which makes it strong) and it drapes well. It gives a smooth, shiny face and the weft shows only on the back. Can be used for curtain linings, evening wear, upholstery, ribbons and trimmings, depending on the fibre used - such as cotton, polyester/cotton, acetate, polyester or silk.
The Twill Weave produces fabrics with diagonal lines which generally run bottom left to top right on the fabric face. By weaving twills in various directions you create fabrics such as Herringbone or Chevron. This particular weave causes fabric to drape well, it is one of the most used weave constructions. It produces fabrics such as Gabardine or Denim. This construction is used for a wide range of textiles such as suits, jackets, trousers and curtains. Viyella fabric is a 2/2 twill fabric.

There are also Crepe Fabrics that have no definite pattern and have a crinkled or puckered surface on the face of the fabric. Wool crepe fabrics are used for high quality suits. It is produced by using:
a) S&Z high twist yarns
b) a crepe weave construction
c) a chemical or thermal treatment to shrink the fabric differently

These are your Knits.
I remember the Warp knit simply because it is the knit style that is Warped and looks a bit strange. The wales of the knit are distorted which makes it easily identifiable.:

Characteristics of a Warp Knit: 
1) Requires a full warp sheet.
2) The loop-forming yarns are fed in the direction of the length of the fabric.
3) Can not be unravelled, usually does not ladder.
4) Knitting needles always work together as a unit.

You can get different types of warp knits for example:
a) Open lap: the feet of the loop do not cross.
b) Course: a row of loops across the fabric width.
c) Inlay: a yarn between the loops and the underlaps across the width.
d) Closed lap: the feet of the loop are crossed.
e) Wale: a column of loops in the length direction.
f) Vertical inlay: a yarn laid between the loops and the underlaps in the length direction.

This is a Weft Knit. This particular knit is the most basic structure of knit that there is, it is where the wales of the knit move in a horizontal (left) train.

Characteristics of a Weft Knit:
1) May be made from a single yarn.
2) The yarn is fed crosswise to the length of the fabric.
3) Can be unravelled; may ladder.
4) Knitting needles can work sequentially or all together.

These are your Nonwovens.
You have your Felts  (Wool felt & Needle felt) and your Bonded Webs (Dry laid, Wet laid & Direct spun)

Wool and some other animal fibres become progressively entangled and eventually turn into felt., aspects such as alkaline liquors, heat, pressure and repeated mechanical action can catalyse this. A fulling machine alternates and repeats compression, beating and squeezing until the required density of felt is achieved.
Felts are good insulators and so can be made into warm garments used today. However, main applications include hats, collar backs for jackets and coats, furnishings, roller coverings, insulation materials, billiard cloths, conveyer bands in paper making.

This is a Needle felt. A bulk of fibres are continuously pentrated by a bank of barbed needles fixed in a single needle board. At each stroke each needle drags a number of fibres to the lower side of the web, thus forming loops in the fibres.
Needle felts are normally given additional strength by supplementary fibre-bonding techniques.

Bonded Webs

1) Random-laid (air laid) web
Webs are either random-laid or oriented.

2) Oriented web
3) Adhesive bonded web
Adhesive may be applied by spraying, dipping or foam spreading, followed by pressing.
4) Web bonded by low-melting fibres
A small proportion of the fibres may be of a special type which can be melted or dissolved so that they bond the other fibres.
5)Web bonded by localised melting
Thermoplastic fibres can be fused in small areas at regular intervals.

Dry Laid: When a fibre web or batt has to be made. The fibres can be drawn onto a suction drum.

Wet-Laid: These webs are made as fibres are suspended in a liquid and are then filtered onto a sieve.

Direct Spun: These webs are made by spinning synthetic fibres directly onto a conveyer band.
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