Editor’s note

The images in the right-hand margin (indicated by red numbers within the text) are the slides Karen displayed while she was delivering the lecture. We have retained Karen’s original numbering, so where slides are missing due to copyright issues some numbers will be non-sequential.

Cotton grows inside the seed pods 1-1 of a wide variety of plants of the GOSSYPIUM species, which belong to the Mallow family, and are related to Hollyhocks. There are about 88 varieties of which 7 are cultivated.

The early primitive cottons grew naturally as perennials, and for many years the cultivated cotton plants were also grown as perennials. Nowadays with one or two major exceptions cotton is grown by [raising annual] crops.

In favourable conditions perennial cotton plants grew like trees 1-2 1-3 to a height of 20 feet. Present day plants [naturally] reaches a height of between 4 and 6 feet.

The first place to spin and weave cotton fibres may have been Egypt where cotton fabrics appear to have been known very early indeed. Recent evidence suggests as early as 12,000 years ago.

In China, cotton was known but probably not grown by early civilisations, because the Chinese appear to have regarded it as a great luxury in comparison with their own homegrown silk. Even as late as 502 AD it was put on record that an emperor was presented with a cotton robe.

Marco Polo, who visited China in 1295, described the people and their customs in great detail, but he does not mention the cultivation of cotton which may suggest that cotton has only been grown there since his visit.

In South America, in the very earliest Peruvian tombs quite finely worked cotton lace and brocades have been found.

In North America, in the West Indies, where Columbus landed in 1492, it was noted that cotton grew abundantly there and on the neighbouring coast of America.

The natives were dressed in cotton fabrics made with great skill from cotton fibres, which were likely to have been of better quality than the fibres known in India and Europe at that time, though they were probably not as finely processed as good Indian cloth could be.

It may be impossible to say where cotton fabrics were first made but there can be no doubt that INDIA is the home of the cotton industry.

Scraps of cotton fabrics have been found at MOHENJO DARO in the Indus valley, which have been dated to about 3000 BC through the presence of copper objects that were datable on stylistic grounds.

There are references in Hindu religious works of 2000 BC to the cultivation of cotton. Already by 1500 BC Indian cloth was renowned for its quality and exported under its own stamp of origin.

The early cotton industry appears to have been based on the cultivation of cotton trees.

The Hindu religion regards the cotton tree as sacred, so ornamental cotton trees are still grown in the gardens of India and other Asian countries, where its dark green leaves and red-purple flowers are treasured, though the fibres it produces are now considered too short for spinning.

Cotton trees grew in Assyria during the reign of King SENNACHERIB whose annals of about 700 BC describes “the Palace without rivals” built by him with “A great park into MOUNT AMANUS wherein all kinds of herbs such as grow on the mountains and in CHALDEA as well as trees bearing wool were set out”.

Further on is mentioned that “the woolbearing trees they sheared and wove into garments”.

The Bible has only one reference to cotton, but it is quite a crucial one. It is in the book of Esther and concerns the palace of SHUSHAN and the white, green and blue hangings used to decorate the palace. The Hebrew name used for hangings is KARPAS, while the Indian name for cotton was Kupas or KURPAS, so that means that the hangings were described as “Cottons”.

The book of Esther is dated to about 520 before Christ, which gives the word cotton, derived from Kurpas, via Arabic ‘goton or guter’, quite a respectable age.

Herodotus also wrote of woolbearing trees; he describes a wild plant that produces no fruit, but a kind of “wool which is better and more beautiful than sheep’s wool”.

Alexander the Great 1-5 sent one of his admirals NEARCHUS on a voyage of discovery of Indian waters. He came back with descriptions of cotton trees and of garments made from the wool growing on these trees; but there is as yet no evidence that cotton was grown in hellenistic monarchies – on the contrary, both cheap and expensive cotton stuffs and yarns are taken across either sea or land as exports from India well into Roman times.

The Romans were said to have used cotton awnings at the time of the Apollinarian games in 63 BC.

There were import regulations in some countries. Cotton is mentioned in several of these and the Historian ARRIAN relates that Indian muslins, plain and figured and also raw cotton for stuffing couches and beds were landed into Egypt from India in 131 AD.

There is also a second century letter, where the writer complains of the quality of cotton warp yarns.

Such a complaint must have been a recurring one, because it would have been extremely difficult to handspin the short fibred Indian tree cotton into a reasonably strong thread suitable for weaving.

Indian cotton cloth with the characteristic crinkled or pleated appearance is woven with cotton yarns for both warp and weft. However, even Indian weavers were likely to have found great difficulty in weaving with cotton warp yarns especially if they had been exposed to linen yarns and their much greater smoothness and strength.

Linen weavers might never have had much patience with a cotton warp with constantly breaking threads. Broken threads mean repairs and repairs often mean imperfect looking fabrics because repairs are not always easy to hide – and all to little avail because a very useful cloth for most purposes could be woven with a cotton weft on a linen warp in a fraction of the time so combining cotton and linen yarns must have been an early compromise. Pliny is the first writer to describe the manufacture of cotton yarns for the purpose of weaving on a linen warp.

The confusion of the terms for linen and cotton in ancient texts may be related to the fact of the fibres often being combined in the same fabrics.

This confusion applies to the term BYSSUS which has been variously ascribed to seasilk, linen and cotton, though it may originally have applied to linen fabrics only.

Herodotus used the word to describe Mummy Bandages, but later it was used to describe very fine types of cloth.

If Byssos was meant to describe transparent fabrics, then these fabrics were likely to have been linen, because cotton fabrics have a built-in capacity to obscure vision.

The word may originally have come from an Egyptian word meaning first string or rope and then linen.

Cotton growing became established in some Mediterranean countries in Roman times 1-8, so when the Roman empire collapsed and there was a breakdown of the trading activities between the Mediterranean and the East, cotton fabrics were still produced by using homegrown cotton fibres.

During the 7th Century the Saracens built up their Mediterranean empire and reached to the borders of India. Once again trade grew between India and the West. New caravan routes were established and commerce thrived as it had never done before with much of it based on the cotton industry.

The Moors brought cotton-growing to those Mediterranean countries where it was not already known along with their technical and artistic knowledge. Some of the finest fabrics were made in Spain during the 10th Century. Cordova, Seville and Granada were centres of the cotton weaving and dyeing trades, and their products compared favourably with those of Eastern cities.

Europe however, was too involved in religious struggles to allow any volume of trade with Spain, so when the Moors were eventually driven out their skills in cotton cultivation and manufacture went with them, because no market had been established for any surplus production.

It was different in Italy where cotton from ANTIOCH, ALEXANDRIA and SICILY is recorded to have been weighed in the public scales at GENOA in 1140, and where in VENICE Mediterranean grown cotton now began to be processed.

During the 12th and 13th Centuries the Crusaders who understood well how to further both their material and their spiritual well being also brought cotton into Europe, both as yarns and fabrics and as a concept of fashion 1-9.

The textile Industries of Northern Italy and Southern France began to flourish in step with the arrival of cotton fibres 1-10 and yarns and of course with the interest that was generated and this in turn enabled the trading centres of Genoa and Venice to distribute goods made in Europe as well as the goods arriving from India.

Germany’s cotton industry, built on imported raw cotton and cotton yarns, also began to flourish and grow important, and production began in the Netherlands, France and England.

But in spite of the steady development of cotton spinning and weaving in European countries, people still wanted the Indian cottons, especially the printed ones, which Marco Polo wrote about so enthusiastically. These and the fine muslins, like “spiderswebs” could not be done as well in Europe, so the caravans and ships continued to bring Indian wares, made in India by Indian Craftsmen to Europe.

The knowledge of these imports is confirmed by the cotton materials which were found in refuse heaps at FOSTAT. These were dyed and printed in simple designs, [most] unlike some of the Indian printed fabrics, that we can still buy. Their timeless type of design, often make the fabrics appear older than they are.

One special virtue of the pieces found at Fostat, now a suburb of Cairo, is the proof they give of the existence in Europe of Indian exports from approximately 1000 AD to 1500 AD.

These exports probably came from GUJARAT on the west coast of India. Ships coming from there are known to have sailed through the Red Sea to Fostat which was then an important transit port, where Italian and other European traders, as well as traders from MEROË (now the Sudan) met their Arabian colleagues and their respective goods changed hands.

The term Fustian may first have been applied to Indian cottons sold at Fostat in the same way as CALICOS were named from Calcutta.

Goods from Fostat were taken to Venice and Genoa for resale and export to every country in Europe, going as far afield as Iceland and Norway.

A description of cotton garments made from red “fustian” have been found in Icelandic texts of about 1200 AD which refers to events that took place in 960 and 1179 and in an inventory of 1321 from a Norwegian church, three vestments, one red, one white and one described as old are mentioned as being made from “fustian”.

People were intrigued by everything to do with Cotton which would arrive in the Northern European countries in its raw state, as well as made into yarns or fabrics.

Since cotton only grows in warm climates, Northern people could have little understanding of the way it is grown and processed, especially since what they saw of the fibres reminded them of wool.

There were numerous speculations and superstitions regarding this new material – at one stage cotton seeds were thought to be useful for curing asthma, coughs, dysentery and wounds and as an antidote for poisoning, while oil extracted from the seeds was believed to take away spots and freckles.

It was also believed that the cotton fires were the wool of lambs that grew and lived attached to branches of trees. This belief was fostered purportedly by Sir John Mandeville, described as a man of learning and substance, who set out from St. Albans in 1322 to see the world and did not return till more than 30 years later.

His reports state that he travelled through all the kingdoms of the world and in one of these “there groweth a manner of fruit as though it were gourds, and when they be ripe, men cut them in two and men find within a little beast in flesh and in bone and blood, as though it were a little lamb with wool outside it”.

About 1600 a similar account was given by Baron von Herberstein when he was Ambassador to the Holy Roman Emperor. His account states that a plant resembling a lamb 1-12 grows from a seed to a height of 2 1/2 feet, with a head, eyes, ears and all other parts of a body as a new born lamb. It had very soft wool and was rooted by a stem in the middle of the body, and “when it had eaten as far as it could reach, it died.” It was called a Scythian lamb.

There were many similar tales and misconceptions and no doubt such tales encouraged many of the travellers of the middle ages to travel further afield to satisfy their curiosity.

In 1368, the great Mogul Empire came to an end. Trading with Europe had been favoured but this was now over. With the closing of the caravan routes came a halt with the trade with India along these routes.

After conquering Syria and Egypt the Turks controlled all the trade rates over land and all the ports and sea routes through the Red Sea, so if anyone wanted goods from India they would have to find another way.

Consequently this was the age of the great sea voyages 1-13 for the purpose of sailing around the world to find India.

Columbus discovered America instead but Vasco da Gama did arrive in Calcutta in 1498 via the Cape of Good Hope. On Christmas Day 1497 his ship passed NATAL and Vasco da Gama named this country accordingly.

For the next 100 years Portugal monopolised the seaborne trade between Europe and the East. Their Goanese colony was founded in 1510 with Portuguese trade and interests.

From Lisbon cotton was shipped by the Dutch to Antwerp, Bruges and Haarlem, and from there exported further afield.

While the Portuguese controlled the Eastern sea routes and the Spaniards the routes going to the Americas, there were various attempts by the Venetians, together with other western traders and the Arabs to break their monopolies, but they did not have much success till 1588 and the defeat of the Spanish Armada.

Opening the sea routes from Europe to India paved the way for the great trading companies that were built up largely on the cotton trade. The British East India Company formed in 1600 was followed within a few years by those of the Dutch and the French and the first steps were taken towards the creation of the European 1-14 trading empires.

Germany had been the leader in the fabrication of cotton materials in Europe till 1618 and the beginning of the 30 years war, but after that date, England became the greatest consumer of raw cotton and her industry grew and flourished with the influx of protestant refugees who applied the skills to the cotton industry, which they had learned as linen and silk weavers and so they helped to found the Lancashire cotton industry.

From the end of the 17th Century Britain began exporting cotton goods in ever increasing amounts. This was an export with roots quite a long way back, because already in the late 15th Century English cotton goods were mentioned as cargo in Goanese ships.

From the 17th Century onwards the cotton industry in Britain came to rely almost exclusively on the American export of raw cotton. This is a recent slide of a cotton field 1-15.

Lancashire cotton goods were even sold in India, where the fine qualities of cotton goods of the “Woven Air” variety could no longer be made because of mismanagement and consequent deterioration of the cotton plantations, which eventually caused degeneration of the plants.

Exports went to all the British colonies 1-16 and most other countries of the world and British cottons became renowned for their quality as well as their relative cheapness which meant that the market included all classes of society which now began to have several more strata because of the growth of industry generally.

The success of the cotton industry did not please the linen and wool producers of Great Britain or abroad, and they did what they could to hold back the progress of cotton manufacture but were eventually defeated. A law passed in 1700 to prohibit the sale of cotton goods was repealed in 1736 as a result of public agitation.

It could not in any case have served their purpose because Daniel Defoe wrote in 1727 about Manchester that “The grand manufacture which has so much raised this town is that of cotton in all its varieties”.

The export of high quality raw cotton grew until July 1861 and the American Civil War. The blockade of southern ports continued for four years, and Lancashire had to endure the miseries of a cotton famine and its disastrous effects on her population. There were important commercial results, however.

Among them was the opening up of new sources of supply. India was encouraged to improve her cultivation practices and to use better plants. Some of these came from America, who had since 1621 cultivated cotton grown from Indian and Mediterranean seed. These strains had improved on American soil and other strains had been developed and added. The excellent long stapled Barbadian type had been grown on the American mainland since 1664. The old flax growing country Egypt also began to grow cotton. Sound plants and proper cultivation on some of the best soil in the cotton growing latitudes combined to grow very high quality longstapled cotton fibres.

After the Civil War the United States production of cotton supplied the main bulk of raw cotton to the Lancashire mills and continued to do so up to the great war. In addition they eventually developed their own manufacture which began as far back as 1638 when Master Ezekiel Rogers of Rowley Massachusetts brought 20 families from England to assist in his enterprise. About the same time William Penn helped to establish a factory in Philadelphia.

A little nearer our time and soon after the Civil War textile machinery was smuggled out of England and France and technical knowledge of textile production and processes was brought out by weavers seeking new homes in the now United States.

The large consumer countries of the East have developed their own industries to supply their needs and Japan now buys all the raw cotton that India is able to export.

Cotton forms the backbone of the world’s textile trade. About ¾ of our textile fabrics are made from cotton. The U.S.A. grows 7 1/4 million pounds every year. The U.S.S.R. nearly, 4,000 million pounds, China 2½ mil., India 2 1/4 and Egypt about 1,000 mil. Many more millions are grown in other countries adding up in all to 25,000 million Ibs. of raw cotton grown all over the world 1-17.

Cotton growing 2-1 and picking are processes familiar to many through literature and depictions from most of the cotton growing countries, which are all situated between the north and south latitudes 2-3 of 40 degrees.

We know that cotton picking in the past was always done by hand, and that it was a protracted business which went on during the late summer and early autumn, because all the bolls of a plant did not mature at the same time.

Mechanical pickers have now been developed, but they are not universally used, because the cotton they pick includes a high proportion of leaves and unripe bolls, which increase the amount of cleaning needed and also tend to strain the fibres. Even so, in the U.S.A. about 90% of cotton is now picked mechanically, and new machinery is being devised to improve the cleaning of mechanically picked cotton.

In “Cotton” by C.P. Brooks the processes in use in 1898 are depicted from growing 2-4 onward.

After picking 2-5 2-6 2-7 and drying the fibres are separated from the seeds by a process called ginning; Ginning 2-8 is done by the growers – more or less well – because they want the seeds either for next year’s crop or to be crushed for oil and seedcakes for cattle food.

In India cotton came to be ginned by the aid of a type of roller gin called a CHURKA 2-9a 2-9b. There were two popular types of Churka, one which needed 2 people to work it, one for turning the upper roll with a staff, the other for turning the under roll with a crank, while feeding in the cotton. The second version could be operated by one person.

More developed forms of roller gins are still used for long stapled cottons. Modern roller gins consist of leather discs attached to a wooden roller. The leather surface of the revolving roller passes close to a “doctor” knife leaving a space through which fibres can pass – but seeds cannot. As the roller revolves the fibres cling to the leather surface and are carried through the gap between the leather and the knife. The seeds are caught by the knife and removed.

The invention of Eli Whitney 2-10 of the saw gin in 1793 was a vast improvement on the churka – especially for short stapled fibres. It developed 2-11 a series of circular saws, mounted on a frame and turned by a fly wheel, nearly in contact rotated another cylinder mounted with brushes so that the seed was removed by the action of the saw teeth against the brushes.

At first 2-12 the cotton was blown into the lint room to be baled, later it was drawn forward by the air current onto a surface of wire covered drums or screens to be delivered in the form of a sheet and deposited on the floor 2-13, later still a conveyor belt was attached for the cotton sheet to be carried to a baling and packing room and baled ready for export to the spinning factories.

Lint sheets could be compressed 2-14, so that great quantities could be rolled into bales that were easy to roll out again on arrival at the spinning mill. This had economic advantages too, because the old type square bales 2-16 were of uneven size, less compact and more liable to damage. The packing and shape of the bale 2-17a 2-17b 2-17c 2-17d was distinctive of the area from whence it came and one way in which an expected quality could be recognised.

The bales were transported 2-18 2-19 2-20 2-21 by the [buyer] to the factories.

Spinning preparations

On arrival at the factory the bales are broken up by a BALE BREAKER with several spiked rollers revolving at high speed. The spikes tear the tightly packed cotton apart, loosening the fibres and so allowing many of the impurities which normally amount to 2-3% of the weight of a bale to be sifted out.

Willowing

After that a series of SCUTCHING and WILLOWING 2-24a 2-24b machines are used for further cleaning and separating of the fibres. All of these operations had of course been done by hand 2-25 in various ways 2-26 but some form of mechanical help was soon devised from the bowing 2-27 onwards.

Eventually a machine was devised to assist the beginning of the next stage of processing cotton fibres into yarns. This machine delivers the fibres in the form of LAPS, which are continuous sheets of fibres about 40″ wide, an inch thick, and look like an enormous piece of cotton wool.

Carding

The next process is CARDING on a CARDING ENGINE which delivers the cotton as a filmy webb. This web is eventually drawn together to form a loose rope 2-29a 2-29b of fibres called a SLIVER.

Slivers are stretched and drawn in stages through a DRAWING frame, consisting of a series of rollers, like a succession of wringers in which each set of rollers is revolving slightly faster than the previous set.

They are dropped into cans between each operation and next fed into the DRAWING FRAME in groups of 4 to 8. As they pass between the rollers, they are drawn out finer and finer and each time the fibres become more closely aligned.

The more the cotton is drawn out and straightened the finer and more uniform the yarn will be though it is of course, the inverse proportions 2-30 of the diameter to the length of the fibres which determine the spinnability of the different types of cotton and consequently the quality of the finished yarns.

Combing

For fine or high quality yarns, the cotton is first combed to align the fibres still more accurately and to remove more of the shorter fibres and neps 2-31 which are immature fibres.

This is done in a COMBER. The sliver from the draw frame is converted into smaller laps. The laps are combed by a revolving cylinder equipped with many needlelike spikes and come from the comber in a fine webb, which is again collected into a loose rope or sliver.

Several of these are drawn through a SLUBBER or a ROVING frame to become sufficiently parallel and uniform for spinning. At this stage the sliver becomes a SLUBBER or a ROVING 2-32.

The roving corresponds in effect to the strand of fibres, which the hand spinner draws out 2-33 from the mass on the distaff to twist and spin into yarn. The simple operation of pulling out a strand of fibres provided some degree of alignment to the fibres and the spinner was able to exercise his skill by the way he twisted and stretched these during the spinning process. In a way the mechanisation of spinning was a comparatively simple matter but the mechanisation of drawing out cotton slivers until they were ready for spinning was far from simple because machines can only work with and produce goods of a uniform type.

Lewis Paul 2-34 of Birmingham stated this process in 1738 when he invented the first carding machine, consisting of 2 spiked rollers for the cotton to pass through.

Spinning

Between 1764 and 1767 James Hargreaves 2-35 developed the spinning engine or jenny on which several threads or yarns could be spun at a time.

Richard Arkwright 2-36a 2-36b improved the method of using rollers for drawing out the fibres during spinning.

Arkwright’s invention enabled the spinner to produce a finer and firmer yarn than had been possible with Hargreaves’ jenny.

Between the years 1747 and 1779, Samuel Crompton of Bolton followed up these inventions and combined the principles of Hargreaves’ jenny and Arkwright’s frame into a machine called the MULE 2-37a 2-37b. The mule could spin fibres into yarns much finer than any previously manufactured. In mule spinning the rovings are drawn out and mounted on spindles on a moving carriage. As this runs outwards, the spindles revolve to twist the roving into a yarn or thread which is wound up as the carriage returns in the opposite direction 2-38 2-39.

The modern spinning process is called ringspinning and is done on a more compact machine without the moveable carriage. The operation of the ringspinning is continuous by contrast with the to-and-fro intermittent movement of the mule. The basic operations of stretching and twisting the roving are, however, the same.

With the help of new techniques and the electronic microscope 3-1 3-2 it is possible to examine the inside of textile fibres and determine their internal make-up.

Cotton fibres have a cuticle wall and an inner wall. The cuticle wall is a tough protective layer, which formed the shell of the fibre during the early days inside the BOLL. It makes up about 6% of the fibre.

Besides cellulose chemical analysis of primary wall material has shown that it contains 1 to 1 1/2% protein, 1% pectic materials, 1% mineral substance, ½% wax and small amounts of organic acid, sugar and pigments.

Cotton fibres have a natural lustre which is in part due to the wax on the surface and is increased in the types with a nearly circular cross-section.

The inner wall is almost pure cellulose; if the non-cellulosic materials are chemically removed, the cellulose fibrils can be seen as a felting of tiny threads, consisting of long cellulose molecules held tightly alongside one another by the natural cohesive forces of attraction exerted between close packed molecules.

The formation of the walls and the criss-cross network of fibrils which forms the outer layer gives great peripheral strength. The fibrils of the inner layer confers great strength lengthwise, both through their longitudinal direction and through their convolutions.

Although the fibrils of cellulose forming the fibre walls are compact and relatively impervious to water penetration, there are sub-microscobic spaces between the fibril network of the cuticle, the fibres themselves and inside the lumen.

These spaces which add up to 20 to 41% of the fibre volume makes it possible for water to penetrate the fibre by capillary attraction.

Water molecules attaches themselves by chemical links to groups of the cellulose molecules by forcing these apart and destroying some of the rigidity of the cellulose structure. Water acts as a kind of “plasticizer” for cotton and is responsible for a number of important features in the processing of cotton fibres.

When the cellulose molecules are lubricated by the water molecules the fibres become plastic and easily deformed and the effect of pressure on wet cloth is identical with its effect upon any other plastic – it changes its shape because the fires will accommodate themselves to the force applied to them. Ironing can give a smooth flat surface because of this fact and if a piece of material is passed through pressure rollers it can be glazed or stretched or given a watered design.

However, all these operations can be reversed in the same way by making the material wet. Wetting cotton material appears to shrink it. This is because the fibres become shorter as they swell with the water. Sometimes shrinking appears greater as a consequence of the fibres also having been stretched during the spinning and weaving, but the fibre is actually dimensionally stable.

The ability of cotton to take up water has been used in a number of ways. Tightly woven rainwater and tentcloth take advantage of the fact that cotton swells in water and can close up the interstices of weaving and so prevent water from getting through.

A most valuable application of this swelling of cotton is in the process known as MERCERIZATION. Here a strong solution of caustic soda is used to bring about and retain an intensive swelling of the fibres. Mercerization was discovered in 1844 by John Mercer; he was working on the filtration of different chemicals through cotton filter and noticed how this filter changed, when it had been used for caustic soda and became smoother and heavier – more solid, and smaller.

The overall shrinkage in the fabric comes from the strains between the threads releasing themselves, which help to make it stronger and easier to dye.

The mercerization process was taken a stage further in 1889, when H.A. LOWE found that by stretching and holding the cotton stretched, so as to prevent it from shrinking during mercerization, it developed the beautiful lustre, which we now associate with the process.

The reason for this development is that cotton fibres regain their original circular cross-section due to the swelling of the cellulose which also make them tend to lose their convolutions. If they are held in a stretched condition they cannot take up the strains by shrinking, so the plastic cellulose deforms permanently and the cloth or yarn develop a smooth surface capable of reflecting more light.

After washing and drying the mercerized cotton fibre retains its new appearance.

Mercerized cotton is chemically little different from ordinary cotton. It has a different physical form, but it remains almost pure cellulose, just slightly more reactive – it can now take up about 12% of water from the air. Compared with cotton’s usual 6-8% this is a difference that may influence our choice of conservation material.

Sulphuric and other acids are also used to swell cottons and yield effects that resemble those of mercerization. Acid finishing of the modern kind, can be used to provide a number of different effects, but though the cottons retain the essential fibre structure of the original cotton, their cellulose has been subjected to chemical modification. It is no longer cellulose but a chemical derivation of cellulose.

Cotton fabric can be made wool-like or more transparent or stiffer to be like organdie, the effect produced depends on the fabric and the conditions used for the various processes, but in most cases, it is the swelling of the cotton fibres that is the most important factor.

The success of these treatments stems from the fact that the cellulose of cotton is an active chemical, whose character and behaviour can be altered by chemical treatment to provide entirely new types of fabrics with new properties.

The tensile properties of cotton fibres and yarns are affected appreciably by the amount of moisture absorbed by the fibres.

Under average humidity conditions, cotton takes up about 6-8% of moisture. At 100% humidity cotton has an absorbency of 25-27%.

The humid atmosphere 3-6 of Lancashire was peculiarly favourable to the spinning and weaving of cotton during the early years of the industry. The damp yarns and threads were not so inclined to break during manufacture. Today humidity in a factory can be controlled as easily as temperature, so the climate of Lancashire is no longer a critical factor in the cotton trade.

Cotton burns readily in air but has an excellent resistance to degradation by heat. It begins to turn yellow after several hours at 120 C and decomposes markedly at 150 C as a result of OXIDATION. Cotton is severely damaged after a few minutes at 240 C.

Cotton shows only a small loss of strength when stored carefully. It can be kept in storage for a very long time without showing any significant deterioration. After 50 years of storage cotton fibres differ only slightly from a fibre a year or two old. Ancient samples taken from tombs more than 500 years old have been tested and still had ⅘ of the strength of new materials.

Sunlight causes gradual loss of strength and the fibres turn yellow. The degradation of cotton by oxidation when heated is encouraged by sunlight. It is particularly severe at high temperatures and in the presence of moisture. Much of the damage is caused by ultraviolet rays and by the shorter waves of visible light.

Cotton has an excellent resistance to ALKALIS: this together with its strength endows cotton garments with a long useful life. Cotton can withstand repeated washings, and is therefore ideal for household goods and garments that need laundering time and again. The resistance of cotton to washing and wear is matched by the permanence of many cotton dyes, especially vat dyes. The use of suitable dyes may lengthen the useful life of a cotton fabric.

The cotton fibre is fairly stiff and rigid, so cotton yarns and fabrics are not generally as flexible as those made from wool or silk. To achieve flexibility cotton can be spun into fine yarn and made into tight woven fabrics. This is how cotton poplin, voiles and flannelettes are made and why these materials are both flexible and crisp. The versatility of cotton combined with its cheapness and abundance has made it into the most widely used textile fibre. It goes into boots and shoes, carpets, curtains and clothing of all sorts. Heavy cotton yarns and materials are used for tyre cords and marquees, tarpaulins and industrial fabrics of all descriptions.

Wherever a fabric is needed which is strong, hardwearing versatile and cheap, cotton is usually the answer.

I will finish by showing a few more slides to remind you of some of the aspects of the manufacture of cotton which we have just touched on in this lecture 4-1 4-2 4-3.