Chapter XXII: China and Earthenware Manufacture: Potters’ Rot

In all dusty trades pulmonary disease is the cause of death of large numbers of the workpeople. The manufacture of pottery is a dusty trade. Potters’ asthma and consumption have for long been known. The potteries of Staffordshire formerly had an unenviable notoriety on account of the prevalence of ill-health, and the large death-rate among the hands employed. For much that we know of the pulmonary diseases of potters and of _pneumoconiosis_ in general we are indebted to Drs Greenhow, Addison, Peacock, and the late Dr J. T. Arlidge, who, as Physician to the North Staffordshire Infirmary, Stoke-upon-Trent, had unusual opportunities of observing and recording the prevalent diseases of that district.

In the manufacture of china and earthenware the workpeople are exposed to two dangers: (1) pulmonary disease due to inhalation of particles of clay and flint; and (2) plumbism in consequence of the presence of lead used in the glazes and for colouring purposes. In another part of the book the dangers incidental to lead poisoning in potteries are dealt with. Here we are concerned with mineral dust solely, and its effect upon the lungs. Cheap pottery is made from ordinary clay, but in the manufacture of the finer ware, Cornish clay and stone are used. In firing china, ground flint is largely used as a packing between the cups, saucers, and plates, etc., when these are placed in the “saggers” or burnt-clay boxes in the ovens. In addition to the ingredients mentioned above, ground calcined bone is also one of the constituents of china.

Clay and flint both contain very hard, sharp, angular particles of silex, which when drawn into the respiratory organs during inhalation are not dissolved by the secretions of the bronchi. They become deposited in the smallest bronchial tubes and the pulmonary alveoli, and set up irritation. The initial process in the manufacture of earthenware consists in mixing the clays with ground flints and water. This is rather a dusty operation, but fortunately only a few men are employed at it. When properly mixed, the compound is known as “slip,” and the men are called slip-makers. The mixing of the slip is sometimes done by hand by means of long, broad pieces of wood, but usually by machinery. The next stage in the manufacture is known as “throwing,” where the potter throws moist clay upon a revolving wheel, and by means of his hands and fingers shapes the clay into all forms of useful dishes, elegant vases, etc. These products are known as hollow ware, but other kinds of ware just as useful, _e.g._ plates and saucers, can be made by pressing. The clay vessel when removed from the potter’s wheel is felt by the fingers when run over it to be rough and uneven, and in order to get the required smoothness it is necessary later on to turn such hollow ware as cups upon a lathe, while flat goods like plates and saucers are made even by being rubbed with tow or flannel upon a rapidly revolving table. This process is called “towing.” Ware thus smoothed is ready for the oven. The first firing is known in the trade as “biscuiting.” After this it is ready to be painted or imprinted by coloured transfers, and then glazed. The ware to be fired is placed in large thick-walled vessels the size of an ordinary cheese, made of very coarse local clay, and known by the name of “saggers.” These are capable of withstanding great heat. Into these the earthenware and china goods are packed, care being taken to separate the individual china pieces from each other by plenty of loose ground flint. The men who carry the saggers into the kilns are called “placers.” They build up the saggers on the top of one another, pile after pile, and when doing this they are naturally exposed to alternating heat and cold, to high temperatures in ovens just emptied, to the fumes of sulphur in the kilns from the expiring fires, and to a considerable amount of dust when emptying the saggers. Coming out of the warm kilns covered with perspiration they run the risk of getting chilled.

In this description of the manufacture we have simply dealt with ware that has not been glazed or in any way brought into contact with poisonous compounds, such as lead. The products have only once been fired. Should the biscuited ware be subsequently glazed, this is done by dipping it into a liquid which contains, among other things, “raw” or “fritted” lead. The man who plunges the ware into the glaze is called a “dipper,” and he is followed in his work by the dipper’s cleaners, who rub the rough edges off the ware, while the person who places the dipped ware in the saggers, which go again into the oven for a second firing, is called a “glost placer.” The workman who fills the unglazed ware in the saggers and carries them into the kilns for the first firing is, as already stated, called a “placer.” He only incurs such risks to health as might be caused by exposure to varying temperatures and to dust, but the “glost placer” runs in addition the risk of lead poisoning. About 3 per cent. of them suffer from plumbism.

Since, however, we are only concerned at present with dust and its effect upon the respiratory organs, we shall adhere to a description of those processes in potteries in which it prevails, and of these the two that are the dustiest and the most dangerous are “towing” or smoothing of the ware before it has been fired, also what is known as the “scouring” or cleaning of china after it has been biscuited. The scouring of china is generally done by women, sometimes by hand, by brushing the ware over a wooden trough so that the ground flint can be collected and used over again. The atmosphere of the workroom is often thick with dust, while the hair and clothing of the women are literally white with the fine particles of flint. For dust and danger there is no comparison between the throwing and turning of unfired clay products and the cleaning of china that has been once fired. Unless provision is made by fans for the removal of the dust, the air is so thick that no person could scour china for even a few weeks or months without suffering from bronchial irritation or bronchitis, cough and shortness of breath. Dr Prendergast of Hanley, Staffordshire, informs me that after two months’ work in scouring china, a healthy woman will often present symptoms suggestive of phthisis, but happily the condition of the lung is remediable. Potters’ asthma and consumption, as indeed all forms of lung disease due to dusty occupations, are becoming fortunately fewer and fewer every year in this country, owing to the improved appliances in factories for getting rid of dust. The late Dr Arlidge told me that the chances of obtaining a good illustration of potters’ phthisis as a pathological specimen was becoming increasingly difficult, and the same information has been sent to me from Sheffield as regards steel grinders’ lung.

In addition to visiting the largest potteries in England and Scotland, I have had the opportunity of inspecting many on the Continent, and particularly the porcelain works at Limoges, where I saw something of the baneful effects upon the French potters of the scouring of china. In Limoges the porcelain is made from a very fine white clay or kaolin, which is found in the district. The products made from this kaolin are dipped in a glaze containing felspar and quartz, and whose composition is silica 70, aluminium 17, potash 13.

For more than a century porcelain has been manufactured in Limoges, a town containing 80,000 people, of whom, roughly speaking, 15,000 are engaged in the potteries in the town and neighbourhood, men and women about equally. The kaolin is found at St Yrieix, a village twenty-six miles south of Limoges. There is therefore very little expense incurred in the railway transport of the raw material. Labour, too, is on the whole cheap. In Limoges there are sixteen or seventeen large potteries with almost double that number of smaller workshops. The brushing-off or époussetage of the fired or biscuited ware is done both by women and men by means of soft feather brushes. It is a very dusty operation, and where there are no fans for its removal, as in some of the factories I visited, the air was thick with dust. The windows were open at the time, but currents of air obtained by this means exercised no very appreciable influence upon the dust. It is not this kind of ventilation that is required under these circumstances. In the matter of the provision of artificial means for the removal of dust and the renewal of air in the potteries of Limoges, some of the manufacturers seemed to me to be rather behind than in advance of the owners of large factories in Staffordshire. Accordingly I was not unprepared for the information that among the potters, especially the brushers-off or scourers, in Limoges, the mortality from pulmonary consumption and chest diseases is high. The harmful operations in porcelain works are the emptying of the kilns, the removal of the ware from the saggers, and the brushing of this ware; while the _hard_ dust that rises during the polishing of the all but finished articles is equally dangerous. The polishing has for its object the removal of any roughness from the edges or surfaces of the ware, and it is generally done on a revolving wheel by means of a broken piece of china, the workman using this as the smoothing agent. The men and women employed in these operations are usually well covered with dust, yet it is seldom that they wear respirators. Fans for the removal of the dust were present in only very few of the factories. The employés objected to them on the ground that they created a strong draught of cold air. Dr Raymondaud, one of the Professors in the School of Medicine, Limoges, has made a special study of the diseases of porcelain makers, particularly of pulmonary consumption and chronic bronchitis. He found that the potteries furnished a larger number of patients suffering from lung diseases than did the other trades of the district. Of 75 deaths registered in Limoges as occurring among china makers, 36 were due to phthisis, and of 30 potters whom Raymondaud examined, 20 were suffering from pulmonary consumption. Pulmonary phthisis is regarded as the principal disease affecting the workers in the Limoges potteries.

The discovery of the tubercle bacillus by Koch has tended to unify medical opinion as to the cause of pulmonary phthisis. The bulk of pulmonary phthisis is tubercular and is due to the bacillus. Other conditions, however, are not without their influence, such as hereditary predisposition, constitutional weakness, infection at home, and the effect of chills; but admitting all these, there is considerable evidence in favour of the view that dust plays an important part in producing potters’ phthisis, which, as previously remarked, differs in some respects from tubercular consumption. Dr Lémaistre, with whom I discussed this subject, had analysed the air of the Limoges potteries, and he found that the dust in some of the workshops is composed of earthy particles, fragments of granite, flint, particles of dried glaze, soot, and wood charcoal. The atmosphere which the brushers-off, the finishers, and the porcelain makers generally work in, he found contained 640 million particles of dust to the cubic metre, while several of the finishers, _i.e._ those persons whose duty it is to remove the excess of dried glaze on the ware, often work in an atmosphere containing 680 million particles to the cubic metre. The particles in the latter instance are smaller than those first mentioned, and they therefore remain a longer time suspended in the air of the workroom. This large number of particles of dust in the air is one explanation of the frequency of bronchitis and of pulmonary disease, and also of the small chalk-like masses found after death in the lungs of porcelain makers, but which must not be confounded with cretaceous tubercles. Whatever may be the influence of the dust-laden atmosphere of a pottery in causing pulmonary fibrosis, the accidental presence of the tubercle bacillus in addition would go far to aggravate existing pulmonary conditions, and tend to transform a non-tubercular affection of the lungs into one of a true specific character. It is thus that the presence of a tuberculous person in a workroom becomes a source of danger to his fellow-workmen. Particles of clay or china dust, when inhaled, can only act mechanically upon the lining of the small bronchial tubes and pulmonary alveoli, but by making a breach upon their epithelial coating they reduce the local vital resistance, and pave the way for the entrance of the tubercle bacilli. Dust, therefore, weakens the lung, and by altering its structure, induces conditions that favour the development of the tubercle bacilli. Apart from bacillary infection, dust is itself a cause of danger: it is capable of inducing bronchitis, and if long inhaled causes fibrosis of the lungs of potters. The pulmonary consumption of porcelain-makers differs from tubercular phthisis in the fact that it is of slower development, and is of longer duration; that it less seldom attacks the young than those of middle life and more advanced age; also that there may be found in the lungs after death calculous concretions, which on chemical examination are found to be composed of carbonate and phosphate of lime, silica, and oxide of iron, with a certain amount of organic matter. The average age at death of men from fibroid phthisis in the potteries of Limoges is forty-three, and of women thirty-eight years. The same symptoms just described as having been observed in the Limoges porcelain-makers are also found in workers in pottery in this country, viz., cough, shortness of breath, and progressive emaciation, but there is a greater tendency to blood-spitting in French porcelain-makers than Arlidge found among the potters in Staffordshire.

_Symptoms._--It is not until an individual has worked, as a rule, some months or years at his trade that he shows signs and symptoms of potters’ phthisis. In this, as in other forms of chronic pulmonary disease, there is cough on getting up in the morning, but this circumstance attracts little or no attention, as the general health usually remains good for a lengthened period. At first white and frothy, or speckled from the greyish-black dust that has been inhaled, the expectoration by degrees becomes purulent, while the cough, no longer confined to the morning, becomes more paroxysmal in character, and is attended by shortness of breath, which tends to get worse with time. On examining the chest it is found that the amount of shortness of breath or dyspnœa is out of all proportion to the amount of consolidated lung that may be present. It is a fact well known to every member of the medical profession that tubercular consumption much more frequently affects the apices or uppermost parts of the lungs, _i.e._ just below the collar-bones, than the lowest portions, a circumstance very largely due to the imperfect inflation or ventilation of those particular regions, so that when they become the seat of catarrh or of subacute inflammation, the morbid products that are secreted and effused are, owing to the limited range of movement of this part of the chest wall, and incomplete aëration of this part of the lungs, with difficulty expectorated. A catarrh therefore tends to linger in the apices of the lungs, and offers opportunities for bacillary infection. In dust diseases of the lungs, on the other hand, it is not the apices that become affected so much as the lower and back parts of the lungs. This is an important distinction between the two, for it shows that a different cause must have been in operation. Limited areas of dulness, indicating small patches of consolidated lung, can be detected here and there in the chest, especially at the base behind or close to the shoulder-blades. In the early stages there is neither the evening rise of temperature, the feverishness, nor the accelerated pulse and rapid loss of flesh which are so pathognomonic of tubercle. Arlidge says there is, too, a wonderful immunity from blood-spitting. If an afflicted workman, therefore, at this stage were to give up his employment and seek for some occupation out-of-doors, the chances are that he would still have a good spell of life before him; but if, on the other hand, he is contented to remain at his occupation, sooner or later he becomes the confirmed victim of potters’ phthisis. His vital resistance becomes gradually more and more enfeebled. His preference for indoor life, daily exposure to infection in the factory, and his overcrowded home, lay the individual open to the chances of a tubercular lesion becoming grafted upon a fibrotic lung. Dr Arlidge found that the mean age at death of male potters aged twenty years and upwards was forty-six and a half years, whilst that of non-potters stood at fifty-four. Dr Prendergast tells me that potters working in dust generally die at the age of forty-five. Among potters Arlidge found as the most frequent causes of death pulmonary consumption, diseases of the heart and nervous system. In the workpeople of the district other than potters, while the death-rate from diseases of the chest was 7.86 per cent., the rate for potters was 12.29. Taking the male population generally and their entire mortality from all causes at the time that Arlidge wrote, we find that the deaths of male potters from diseases of the respiratory organs were 60 instead of 27 per 1000, and that the decennial period from fifty to sixty gave the greatest number of deaths, each preceding decennium back to twenty giving less and less, while the maximum mortality from phthisis as opposed to diseases of the lungs generally was reached between the ages of thirty and forty years. Before the age of forty, therefore, the bulk of the potters who have contracted lung disease, and who have become tubercular, die; whereas in those who contract the disease later on they become less liable to the tubercular type of the malady. Bronchitis is met with among the male pressers who are exposed to the dust of the clay, but in china scourers pulmonary diseases are extremely prevalent; as many as 40 per cent. were found suffering from phthisis and 25 per cent. from bronchitis. As already stated, the phthisis in potters is in the early stages usually not tuberculous. So much so is this considered to be the case that Dr John Tatham,[78] at page xcvii. of Supplement to the Fifty-fifth Annual Report of the Registrar-General of Births, Deaths, etc., Part II., 1897, in speaking of potters (earthenware makers) sustaining a mortality from phthisis and respiratory diseases together far in excess of that experienced by other groups of workers, _e.g._ 453 as against 100 agriculturists, says that “potters succumb to non-tubercular disease of the lungs more rapidly than they do to phthisis, and it is certain that much of the so-called ‘potters’ phthisis’ ought properly to be designated non-tubercular cirrhosis of the lung.” Cirrhosis is a medical term sometimes used instead of fibrosis.

_Prevention._--Ventilation of the workroom should be by means of fans and not simply by open windows. Scouring of china by hand over an open trough into which the ground flint falls should be discontinued. It should be done in semi-closed boxes with a strong down draught on the offside of the workers, or by revolving brushes driven by machinery in semi-closed spaces similarly aspirated. Overalls and coverings for the head should be worn by the workers; and since the form of pulmonary disease that affects potters develops slowly and is capable of being at least retarded, if not arrested, in the early stages, in the interests of the workpeople themselves their chest should be examined by a doctor once every three or six months, so that those who show signs of commencing lung disease might be pronounced disqualified for further employment at towing and scouring.

THOMAS OLIVER.