a) The Process of Wool Scouring

Wool scouring or washing is a process that all wool whether destined for the worsted or the woollen system must undergo prior to further processing.

There are two types of scouring in operation,these being the traditional and more common aqueous or water based scour and the solvent based scour.

In both cases the scouring process is designed to remove the suint,dirt,dust, and scourable yellowness where possible from the wool in order to produce a clean product ready for further processing. Vegetable matter is not removed during scouring,but some reduction may occur due to agitation.

Aqueous scouring firstly involves the greasy blending of the various components of a batch or type that is required into a large bin located at the start of the scour.The blended greasy wool is then conveyed into a number of hot and cold scouring bowls where the wool is mechanically agitated and propelled with forks or suction drums causing further more homogenous blending of the fibres.

There are normally six bowls each of which has a double squeeze roller at the end where the wool passes through to squeeze the scouring solution out of the wetted wool along with the grease and dirt prior to entering the next bowl.

Wool grease is extracted with separators from the scouring liquor during processing, and then sold as a by-product ,which is refined into lanolin for the cosmetic and pharmaceutical industry.

Three of the bowls contain detergent the rest are clean rinse or cold suint bowls.

After final rinsing in pure water the wool is then dried through a drum dryer and conveyed into bins prior to pressing into bales ready to send to the spinner if the wool is to be processed on the system.

Or if the wool is to be combed or carbonised the wool continuously flows from the scour into the start of the relevant processing line.

b) The Process of Wool Carbonising

Wool carbonising is a process that all high vegetable matter short and long wools must undergo prior to spinning into woollen yarn. The main purpose of wool carbonising is to prepare the wool for spinning into yarn.

During the wool carbonising process all vegetable matter contained in the wool will be removed in preparation for carding and spinning into yarn.

The harsh process described below causes considerable fibre breakage and loss rendering any long wools used, suitable for the woollen system only. These high VM long wools are generally unsuitable for combing due to the excessive vm.

All wool carbonising plants have their own wool scouring facility located on site where wool is washed prior to the carbonising process. It then follows a continuous line of processing where the wool is treated.

After scouring the wool is then propelled into a bowl containing a 5-7% diluted sulphuric acid solution. The solution saturates the wool as well as the vegetable matter contained in it. Although the acid solution can cause some weakening of the fibre, its greatest effect is on the cellulose based vegetable matter which is now impregnated with acid.

The acid affected wool and vegetable matter are then conveyed into first drying and then into baking ovens where the wool is heated to a temperature of around 95-110 degrees celsius.The wool is baked on the continuously moving conveyer for around 10-15minutes at which stage the vegetable matter contained in the wool has been baked or carbonised.

The carbonised vegetable matter is however still present in the wool and must be removed.  This occurs when the wool is conveyed through burr crushing and dusting machines which crush ,agitate and vacuum the wool to remove all vegetable matter residue from the wool.

The next stage is to rinse and neutralise the acid affected wool and return it to an acceptable PH level which is suitable for the dyers and further processors.

It is also washed in soap solution to soften the wool as well as remove any residue left in the wool. This is achieved by propelling the wool through bowls which contain a diluted solution of soda ash and soap in order to achieve a final PH in the wool of 5-6.

After neutralising and washing the wool then passes into rinse bowls and finally into a bleach bowl where the wool is saturated in a 06-1.1% hydrogen peroxide bleach solution prior to final drying.

The wool is then packed into bales ready for delivery.
This wool is then ready for carding and spinning.

c) The Process of Wool Combing

Wool combing or topmaking as it is also referred is a process that all long wool destined for the worsted system must undergo prior to spinning into yarn.

The main purpose of wool combing is to prepare the wool for spinning into yarn. During the wool combing process vegetable matter contained in the scoured wool will be removed,any short fibres will be removed and the wool fibres will be aligned and formed into a continuous slivertop ready for spinning.  Most wool combing plants have their own wool scouring facility located on site where wool is washed prior to combing.

The scoured wool is then lightly oiled with a water soluble oil emulsion which helps lubricate the wool through the combing process and reduce fibre breakage.

The wool then passes into the carding machine which is the beginning of the fibre alignment and vegetable matter removal process.

During carding the wool passes from rotating drum to drum as a thin veil covering the drums which contain millions of pins (known as clothing). This action disentangles and helps align the fibres as well as removing a considerable portion of the burry vegetable matter from the wool. The veil of wool covering the final carding roller is then made into a sliver form of roughly aligned fibres and collected in a circular bin ready for Gilling.

There are normally three stages of gilling prior to the wool being put onto the combing machines. At each stage the fibre alignment process continues. After the third stage of gilling the continuous sliver is wound into a ball ready for loading onto the combing machines.

At this stage the sliver still has a considerable amount of vegetable matter present as well as short fibres.

It is the combing process which will remove these short fibres and vegetable matter as well as complete the fibre alignment process in preparation for spinning.

The vegetable matter along with the short fibres that are removed from the longer fibres which remain in the wooltop are called noils. Following combing the wooltop sliver put through two finishing gills. The first removes the wave pattern that occurs on the combed sliver due to the action of the combing machine. The second gilling regulates the actual weight per metre of the sliver according to the spinners requirements. The sliver is then wound into a bump or a ball and pressed onto bales ready for delivery to the spinner.

ALL WOOL PRIOR TO ANY TYPE OF FURTHER PROCESSING MUST FIRST BE SCOURED OR SCOURED AND CARBONISED AND/OR COMBED.

Further processing includes:

d) Worsted system and the Woollen System

THE WORSTED SYSTEM

80 % of Australia's wool is used in the worsted system.The worsted system involves the processes involved to convert long wools such as fleeces/pieces and bellies into woven or knitted fabrics and materials. The products that these wools are used in are generally the high quality lightweight to medium weight woven cloths normally used in suiting materials,fine garments and apparel wear. Worsted weaving is the terminology used to describe these products. These wools are also used to make yarn for machine knitting of wool sweaters. Worsted knitting is the terminology used to describe these products. Worsted knitwear is again lightweight and high quality. The suitability of wools for the worsted system is determined mostly by length and vegetable matter. Micron has little to do with its suitability as long X-bred wools are also processed on the worsted system. Longer wools such as pieces and bellies and occasionally fleece wool that have high to very high vegetable matter present, (ie) 6-8 % and higher, often end up in the Woollen system as these have to be carbonised in order to eliminate VM ,which dramatically decreases the length and strength of the wool, making it unacceptable for combing. In order for wool to be converted from the greasy state into a finished worsted product it must undergo a large number of processes. These are:

• SCOURING
• CARDING
• COMBING OR TOPMAKING
• SPINNING
• DYEING
• WEAVING/KNITTING
• FINISHING
• GARMENT MANUFACTURE
  

THE WOOLLEN SYSTEM 

Most of the remaining 20% of wool produced in Australia is used in the woollen system. The woollen system involves the processes involved to convert shorter wools or oddments such as locks,crutchings,lambswool and high vegetable matter pieces and bellies and fleece, into woven or knitted fabrics and materials. The by-products of wool combing such as noils and burrs are also used in the woollen system. The wools that are processed on the woollen system are normally short, and vary in vegetable matter from 0.1% to 20.0% plus. The wools which have higher VM (ie) 3% plus, must be carbonised which adds considerable cost to the finished product. Lower vm wools are scoured only or carbonised in the cloth. Microns used in this system cover the full range from X-bred to fine merino. The products that these wools are used in are generally the medium to high quality heavier weight woven cloths normally used in overcoats, heavier skirts,socks and blankets. Good quality fine felted woven cloths can also be made with the finer microns. Woollen weaving is the terminology used to describe these products. Woollen knitwear,can also be produced on the woollen system,an example would be lambswool sweaters which are still a popular product available today. They range in quality depending on the micron used. The woollen process has historically been a cheaper process than the worsted process and produces a more affordable wool garment, however in recent times with advances in worsted technology the gap has reduced considerably. Because the wool is not combed as such but only carded prior to spinning the alignment of fibres is poorer which produces a rougher,bulkier yarn more inclined to pill and ball in the fabric. The processes involved in converting wool from the greasy state into finished woollen system product are fewer than the worsted system:

They include:

• SCOURING or CARBONISING
• CARDING
• SPINNING
• DYEING
• WEAVING/KNITTING
• FINISHING
• GARMENT MANUFACTURE
• There are also non-woven woollen system products which are used commercially such as Felts (used for cleaning,polishing etc), wool quilts and doonas, sliver knitted woollen underblankets. These undergo a range of different processes to the ones listed above , however the one thing common to all is that prior to further processing the wool must be either scoured or carbonised.

SOURCE: www.lempriere.com.au