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Tartan Ferret

Why does Wool Shrink?

Part I
August 1941

This is a chronicle of ignorance. We start with a very common question and we cannot answer it, "Why does Wool Shrink?" In spite of ancient knowledge of the Fact we can as yet answer but half the Why. This shrinkage is a very curious and important fact, and like so many other wonderful everyday happenings - sunrises and wind and such like marvels - we just take it for granted and don't wonder at it very much. For hundreds of years this curious fact of Shrinkage has been known to wool craftsmen. It has been amply utilised in making clothing of all sorts. Its benefits have been thoroughly appreciated and its drawbacks thoroughly cursed for countless generations. More than that the processes by which it can be brought about and controlled are thoroughly well known - and yet no one knows just how or why one aspect of it exists.

There always were inquisitive folk in this world, but they are much commoner than they used to be. There always were seekers after knowledge, but they were few in ancient times. It always was these curious ones who made progress possible beyond very primitive stages - but Modern Education has elevated Curiosity into a cardinal virtue, and Modern Industry has endowed it with limitless riches, countless temples, innumerable high priests and lesser ministers. Modern Education has also endowed it with a more impressive name - Research. Research has almost run away with us.

0, I wad like to ken - to the beggar-wife says I -
The reason o' the cause an' the wherefore o' the why,
Wi' mony anither riddle brings the tear into my e'e,
- It's gey an' easy spierin says the beggar-wife to me.

It is doubtful manners to quote French - it is certainly bad manners to translate your quotation. Scots is perhaps rarer and certainly less understood, so we may be pardoned for translating the beggar-wife -"Tis fine and easy to ask."

There are really two completely unconnected happenings included somewhat loosely in the term " shrinking." The woollen trade considers " shrinking" as applied only to the final processes by which cloth is brought to its most stable and perfect condition. People generally, and our womenfolk in particular, look upon " shrinking" as that very disagreeable and unhappy phenomenon that steadily diminishes the size of a woollen garment as it goes back and forward to the laundry. These two ideas of the meaning of shrinking actually refer to completely different phenomena. They have no connection whatever, in spite of the fact that they seem to happen in the same way to the same garments. In fact within limits they actually do happen to the same garments. We shall consider the two meanings separately and we shall first consider the trade meaning of Shrinking.
About this part of our subject quite a lot is known. It is so important in the story of cloth making that a whole specialised craft has grown up around it, and Cloth working or Shrinking is quite a large and important branch of Woollen Manufacturing.

This branch of the trade has a separate existence, partly for physical and partly for moral reasons: Physical because of the highly specialised skill and elaborate machinery involved in delivering woollen cloth to the tailor in the most perfect condition; Moral because the shrinker discovers and exposes faults and frauds on the part of the woollen manufacturer. Even in Scottish woollens there is no harm in having some sort of check on the condition of the goods, and the Cloth worker can cure certain kinds of faults that may develop and be undiscoverable in the final stages of making woollen cloth.

Consider what happens to wool during the many processes which we have from time to time described in " Scottish Woollens." As it passes through these many processes and these complicated machines wool is treated with considerable if respectful violence. Under several of these processes wool becomes almost a semi-plastic. In the washing it is soaked in hot alkaline solutions to remove dirt and natural greases, and in this process wool comes perceptibly near the melting point when it might turn into jelly. Then it goes through the ordeal of dyeing - boiling in many chemical solutions. Next it is oiled and passed through the teeth of the teasing and mixing machines - followed by the violence of the carding and the contortion of the spinning machinery. Then the various preparations for the weaving, and finally through the most violent actions of all, the felting, cropping, finishing, and final drying, steaming, pressing, and all the other pullings, pushings, and stretchings involved therein.

However carefully and skilfully these processes are carried out, certain stresses and tensions are created both in the individual fibres and in their combination in the growing fabric of the cloth. Time and Nature little by little release these stresses, and the fibres and the fabrics settle down to a stable condition. The curly fibre that has been straightened gradually returns to something like its original shape. It has been flattened and thinned down by the removal of its natural water and by heat and tension in the drying: it slowly swells back to its natural form. It has become sharp and bristly in the surface shearing of the cloth: it resumes its softness as it loses its sharp edges. The cloth itself has become distorted in the drying and pressing, necessarily made longer and wider and thinner by the action of the processes. More or less all these processes are carried out under heat and wet, and so once more the wool becomes perceptibly nearer melting. All these processes are necessary to the creation of a good solid cloth, but there are left in the cloth what may be called excess tensions which are harmful to the stability, the softness, and the suppleness of the cloth. The trade of the Cloth worker is to study these matters and to help and hasten Nature in correcting them.

Like all ancient processes this cloth working is fundamentally simple - though, like gardening, it calls for skill and judgement in carrying it out. England was the chief modern home of woollen cloth in the final stages of its development, and so it is not unfitting that the trade of cloth working should be centred in London-" dear, d amn'd, distracting town "-and that the principal and most perfect conditioning process should be called " London Shrunk," and that the London Cloth workers are even yet the principal exponents of the craft. So well known has the term London Shrunk become that, like Homespun and many other terms, it has almost passed into trade language, and the London Cloth workers have altered their mark to Shrunk in London, ever since 1931. We do not pretend to be able to give directions for London Shrinking, for each firm has its own carefully guarded secrets. Moreover, it is probable that these details could hardly be put on paper, but consist rather of many small touches that only long experience can impart. The Scottish Woollen Trade is full of such little unimpartible "secrets," and that is largely what gives individuality to the products of the Scottish Mills. As of Chaucer's Miller, it might be said of the good cloth worker, " He had a thumb of gold, padre." This, then, is an outline of the treatment. The cloth as delivered by the Scottish mill is, let us say, 59 inches wide or even 60. It is intended that when used this should be a good 58. It is usually sold on the old Scottish yard of 38 inches, and should come out eventually at 36 inches good measure.

Most of the cloth workers use damping sheets, usually made of worsted. These are soaked in cold water. The web of cloth is then folded into this damping sheet, or it may be that the web is steamed with moist steam or possibly actually sprayed. Anyhow by one of several means the cloth is thoroughly damped and warmed. It is left in this state for one or two days, and is then unrolled and the web is hung up over sticks to dry slowly and gently by natural air. This takes say a further forty-eight hours. When it is judged ready it is taken down and is folded for pressing in the hydraulic presses. Between each layer of cloth is inserted a sheet of highly glazed and very fine hard cardboard, known as a press paper. If the piece is to be hot pressed with a high glaze the papers have been heated in an oven, and special heavy cast-iron plates also heated, possibly electrically, are placed between each web. If the piece is to be cold pressed the papers are not heated. Each press holds ten or fifteen pieces, and it is then pumped up to whatever pressure the cloth worker considers best for the particular job. Pressures generally range from 30 cwt. to 3 tons per square inch.

After possibly twenty-four hours the press is released, the webs are taken out, and the papers changed. If hot pressing is being done, new hot papers are used; if cold, the position of the papers is just altered a few inches so that the marks caused by the edges of the papers are removed by the second pressing. Again the pumps apply the pressure and again the web remains for a day in the press. The web is then taken from the press and is carefully measured and examined see that it is still the required width everywhere and to see that no blemishes are visible. Each blemish - known in the trade as a " damage " - is marked with a bit of coloured thread on the edge of the web and the miserable manufacturer's account is docked of a quarter of a yard. It is at this stage of the work that certain faults of a serious kind come to light. If for any one of many reasons the cloth has varied in width before being dried or if in general it has been too narrow, the manufacturers' drying machinery hides, but does not necessarily cure, the fault. Or the piece may have been badly distorted so that the checks or threads do not pass squarely across the webs. All such faults are exposed by the shrinking - whether honestly overlooked or dishonestly hidden. Some the cloth worker can cure or improve, some he can only make visible. At the end of all this work the cloth should be in perfect condition for the tailor or dressmaker. It should not shrink or change its shape even if the wearer fell into the river. Even if kept on the shelf for years it would unwind in perfect and unchanged order. Of course so far as Scottish Woollens are concerned this must always remain a purely academic hypothesis, because no tailor or dressmaker ever kept a web of Scottish Woollens for any length of time on any shelf - it gets sold at once.

We are often enough asked if cloth working is necessary or worth while. It is also often hinted that if we manufacturers did our work honestly and thoroughly we should be able to deliver our cloth ready for use. It is not possible to answer these questions and charges definitely. There are few pieces of Scottish Woollens that could not be safely used as they leave the mill. It is likewise true that after a skilled cloth worker has dealt with a piece of cloth the difference between a shoddy and a good cloth is difficult to distinguish. But it is always well to make a good thing better. It is not painting the lily, but is adding perfection to goodness. And after all where are you to stop? Is the manufacturer to become merchant? - nay more, is he to become tailor? Is he to stand behind a counter and sell his garments ?

The positions of the manufacturer and of the cloth worker might be likened to the positions of the doctor and the specialist. Both cloth workers and specialists are useful in their trades. We do not charge our doctor with dishonesty or incompetence if he suggests a consultation with some bigwig who has made himself master in his own restricted field. So when we manufacturers advise cloth working it is not to be taken as an admission of failure. This is the end of the first part of our question: the part we are able to answer. It is an important part, though some might say it is not quite our business to deal somewhat ignorantly with a subject barely on the outer edge of our trade. All the same we think some idea of how cloth working is done and how and why this shrinking comes about is needed before it is possible to understand what is meant by that other and more puzzling kind of shrinking. That will form the subject of Part II., and we hope to leave our readers with some ideas about the Hows even if we cannot answer the Whys.

Part II
October 1941

Wool has one peculiar property. This is technically known as the power of milling, or felting, or fulling. This is the property of knitting its fibres together so that they cling tightly to one another and, as it were, support one another in resisting friction and in making a fabric that contains countless little pockets of air. These are the two features that make wool so invaluable as clothing. Wool does not share this property with any vegetable fibre, cotton, rayon, or flax, not even with silk. In fact, it does not share this property with any fibres excepting the coats of a few animals, such as camels and some of the goats. This is specially interesting because these animals are not closely allied to sheep.

Perhaps the best way to get at this whole question is to examine wool itself. Wool is not a fixed and definite product like water, which can quite accurately be described as H2O, even when adorned with the best Scotch. Rather it is like air, which is a mixture varying quite considerably under varying circumstances, though always fundamentally composed of Oxygen and Nitrogen. Wool is fundamentally composed of Keratin. Keratin is also the basis of skin, hair, horns, feathers, ivory, and so forth. It is a very complicated substance allied to gelatine. It is first cousin to the proteins, which dieticians are always telling us we must swallow if we are to be healthy - meat, cheese, eggs, beans, and such like. Heated, dry keratin swells up and chars, and this gives us the most useful quick check of whether a fabric is wool or cotton. Put a match to a thread of the cloth. If it curls up and leaves a thick hard ash it is wool or silk. If it burns right away, leaving nothing but a little powdery ash, it is cotton or linen, or some kind of rayon. Of course, blends make this test a little uncertain in the positive direction, but it is quite infallible in the negative direction. If any fabric burns right away it is certainly not wool. Again, if treated with heat and alkali, keratin can be dissolved, especially in caustic soda solutions, from which the moral is do not use too much soda or ammonia when washing woollens and not too hot water. So long as your hand can bear the heat everything is all right, for your skin and the wool are both keratin. Even the most inexperienced young woman doing her own washing is not likely to melt off her own hands.

""This principle of softening by heat and alkali has given us permanent waving. The hairdresser winds his victim's hair round his myriad curlers. Heat and ammonia are applied. They soften the keratin - that is, the hair. The alkali and the heat are removed. The hair sets. Thus will the barber remould it nearer to the heart's desire. Thus the beautician - most unbeautiful of words - has borrowed a gold mine from the craftsman in wool. But we must not limit ourselves to considering the behaviour of the raw material of wool apart from its practical effect on cloths. We have already said that the peculiar feature of wool is its power of becoming closely entangled into a dense mat. It shares this feature with no other textile fibre, excepting with the coats of most of the fur-bearing animals - camels, goats, and so on. If your pet dog were clad in cotton or linen you would not be troubled by having to comb and brush mats and tangles out of his coat.

In the traditional treatment of Scottish cloths this power was of the greatest importance. The effect of this milling or fulling on our cloths is so great as always to be one of the most interesting and surprising stages for visitors to our mills. You can hardly convince your guest that the raw, miserable-looking fabric that looks like a kind of canvas and that is treated with scant respect on the floor of the examining room is really a lovely soft, delicious cashmere or a bright, fashionable suiting for a millionaire magnate. The amount of shrinking that takes place during milling varies greatly according to the type of cloth that is being made. In the usual Scottish Woollens - if the word " usual " can be applied to any such varying product as leaves our mills - the pieces are woven, say, 60 yards long. Such a " piece " after being milled measures, say, 48 yards.

The cloth that the weaver has left about 80 inches wide has been reduced to 58 inches. That is not an extreme example. It is a pretty fair average for a Scotch Suiting. The old regular Scottish Woollens were a very happy compromise. They were woven loosely enough not to be stiff, to make a good job for the weaver, free of broken threads, and to give the yams room to swell up during milling. They were felted enough to ensure good wear and to blend their usually rich colouring pleasantly. They were not felted enough to lose their pliability. The openness of the weave ensured that the full softness of the wool could reassert itself after the tight twisting of the thread.

All the same, milling must be watched. A certain disintegration of the wool takes place in the process. It is a queer anomaly that although milling improves the wear of cloth, it weakens it. Just what happens to cause this destruction of the wool is not really known. It happens progressively, and many really heavily milled cloths are quite weak. This is something to do with the other fact that shoddies deteriorate sooner than sound wools, which is an undoubted fact even if it cannot be accounted for altogether. And this is not to say that very useful cloths cannot be made of shoddy. But it does make it very difficult to devise any good mechanical method of testing a cloth for the qualities that matter, such as ability to stand wear.

The extensive use of silk for the " decoration " of both suitings and trouserings, and the long preference of fashion for English cloths have tempted us to work for the brightness and smoothness of surface which is natural to worsteds. Some of the supreme wearing qualities and clothing qualities have been lost in working for this texture. There is much less muling in Scotland than there used to be. This point was dealt with fully in one of our earliest " Scottish Woollens "-No. 2, " Woollens versus Worsteds." It is a loss. It is a gain. You can get nothing for nothing. "Il faut souffrir pour etre belle!"

Wool has scales on its surface. These overlap in a way like the slates on a roof, and these scales are built up from the root. They are so irregular in shape as hardly to justify the name of scales. The wool fibre might best be likened to the rough horns of the sheep or to a structure built up out of worn and damaged ice-cream cones threaded on a rope. These scale edges can only be seen with a microscope, for they project very little. Fine merinos are the scaliest, bright wools like Leicestershires are almost without scales. It so happens that the scaliest wools mill the most easily.

Late in the eighteenth century a Frenchman named Monge wrote a paper on " The Mechanism of Felting," and coupled these facts as cause and effect. For a hundred and fifty years this theory of milling has been taught. He deserved to die on the guillotine for having misled us for all these years. Perhaps that is ungrateful, for he was the first to draw attention to the fact that there was a problem to be solved. The writer never could quite convince himself that the theory was reasonable. It seemed always too small a cause for so great an effect.

The theory was that as you rubbed and pounded at the mass of wool fibres they engaged each other's scales, and owing to the direction of the scales on each fibre they worked into each other and could not back out. It was the principle of the eel trap or the lobster pot, or the way the Emperor moths make their cocoons - sort of one-way traffic. It was the way you can make an ear of barley creep up your sleeve, or the way a ratchet works on a monkey-jack. It was not a bad theory, and it accounted for most things. It accounted for the fact that the confused mass of fibres in a woollen thread milled easily because they intersected in a thousand directions; that the tidy parallelism of the fibres in a worsted thread milled less easily because the fibres could only touch each other with the scales in two directions. It accounted for the fact that the locks on a healthy sheep did not felt because all the scales were pointing in one direction.

It was laziness on our part to accept this theory, for it was long ago recognised that it did not quite answer all the Whys. For example, it did not tell us why Leicesters and a good many " hairs " could be milled at all. Since we wrote the first sentence of Part I., our Research Association has published the results of a new inquiry into this " Mechanism of Felting." They have not got very far yet - in fact, they have only got as far as the negative result of disproving the scale theory, which was already becoming a little worn out and moth-eaten.

A very interesting and ingenious series of experiments seemed to show that there was a directional structure in all such animal growths, including human finger nails. These experiments included such nice childish amusements as dragging about a wool fibre tied to a string like a child's toy cart. This was to find out if any side drag were set up by the scales. Another was the almost superhumanly delicate job of making a cast in wax of wool fibres to reproduce the scales in some non-wool material, and to discover if it still showed guidance from the scales. All these many experiments built up a proof that the scale edges had little or nothing to do with the directional movements of the wool strands. Further experiments were made, some of them very ingenious, such as the splitting and polishing of porcupine quills to see if the inner surface retained the same trend as the outside. It did. This was another of the small links in the chain of evidence. So this directional trend of wool does not depend on its surface, but on some structural property of the fibre itself. There is a lot to be done before all this business can be sorted out. But it does give us woollen men a bit of very solid comfort. It seems almost impossible to imagine that any real substitute for wool can ever be made.
The modern method of milling is a fairly accurate process. The cloth is usually washed clean and is then impregnated with warm soap suds, and in this warm wet state it goes to the milling machines. Broadly, there are two types. The old-fashioned type consists of two heavy hammers that alternately fall on the crumpled mass of cloth which lies in a basin so that the mass of cloth turns slowly under the hammer blows. This is a mechanical rendering of the method of dealing with Harris cloths where the neighbours congregate round a long table and thump the wet cloth by hand to the rhythm of ancient labour songs. It is still used for many types of work.

In the other and more rapid method the box mill consists of two very heavily weighted and sprung oak rollers - perhaps a couple of feet in diameter and six or eight inches wide. The cloth is crushed between these rollers and is forced into and through a long narrow box or trough without ends, and of which the lid is held down by heavy weights. By various adjustments of these parts the millman controls the width and length felting of his cloth. The two ends of the web of cloth are sewn together and go endlessly round in the machine, like a squirrel in a cage, until the mill-man is satisfied with the result. Our ordinary suitings and such like cloths will run thus for half an hour or an hour; cloths like army coatings for three or four hours, and cloths like Irish friezes may take more than a day.

Before the modern development of soaps this process was carried through with fuller's earth, a natural clay. For those who like long names this is an hydrous silicate of alumina, and in composition is first cousin to the felspars, sapphires, rubies, topaz and such like Aladdin luggage; also corundum and emery, beloved of engineers, and bauxite, the raw material of aluminium, called after the queer picturesque rocks of Les Baux in that fair France that has temporarily fallen from grace.

After that the earth or the soap is all most carefully washed out and the cloth is ready for drying. We have seen in print, in a trade journal, a statement by someone who should have known better that the shrinker has - amongst other things - to remove sizes, oils, and other foreign substances. There are no such substances left, in Scottish woollens at any rate, and cleaning is no part of the work of the cloth worker in dealing with our cloths.
We finish up our chronicle of ignorance with a perfec

tly barefaced bit of advertising. Owing to the balanced compromises of our processes, SCOTTISH WOOLLENS ARE THE BEST. With one eye - as usual - on our promise to be as truthful as we know how, we say The Best is shared by other makers, but there are none better. In some classes, such as sports suitings, many types of coatings, and a great collection of luxury fancy cloths, we are supreme. We have a very good opinion of ourselves, and in spite of our innate modesty we are, and always have been, ready to back ourselves both in Peace and War!









E.S. Harrison



One of a series of fascinating articles written over the decades  by Edward Harrison who ran Johnstons of Elgin for 46 years from 1920 - 1966.

Commencing with the first in November 1931, the essays were published anonymously by the National Association of Scottish Woollen Manufacturers.

All these essays - and a host of other articles - are freely available in our Archives to Members of the Scottish Tartans Authority.

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