Gustave Courbet, Schlafende Spinnerin, 1853

It’s late, and you’re still awake. Allow us to help with Sleep Aid, a series devoted to curing insomnia with the dullest, most soporific texts available in the public domain. Tonight’s prescription: “History of Sumach Tanning in England, Degradation of the Manufacture of Leather, and History of the Reform Movement,” the first chapter of Leather for Libraries, a 1905 book by E. Windham Hulme.

The section of the leather trade to which this Handbook relates is that concerned in the manufacture of light leathers tanned with a pale tannage preparatory to being dyed. Bark and most other vegetable tanning substances leave a colour on the skin which cannot be removed without detriment to the durability of the leather; the retention of the colour, however, detracts from the purity of the final colour imparted by the dye. The reputation in the past of the sumach-tanned Spanish leather was founded upon this peculiar property of sumach of leaving the skin white, and on this point the wisdom of the ancients has been justified by the results of an exhaustive series of experiments conducted by the Society of Arts’ Committee, which have given to sumach the first place in the list of tannages for light leathers. 

The date of the introduction of sumach tanning into England may, with some show of probability, be assigned to the year 1565, when a seven years’ monopoly patent was granted to two strangers, Roger Heuxtenbury and Bartholomew Verberick, for the manufacture of “Spanish or beyond sea leather,” on the condition that the patentees should employ one native apprentice for every foreigner in their service. This stipulation indicates that the industry was a new one. Following the custom of the times, the supervision of the industry was entrusted to the “Wardens of the Company of Leathersellers in London.” Additional evidence of the use of sumach at this period is afforded by another patent to a Spanish Jew, Roderigo Lopez, one of Elizabeth’s physicians. By way of settling her doctor’s bills the Queen granted to Lopez, in 1584, an exclusive licence to import sumach and aniseed for ten years. Besides attending the Queen in his professional capacity, Lopez was called upon to act as interpreter to the Portuguese pretender, Don Antonio, on his visit to this island. As the result of some misunderstanding with Antonio, Lopez was induced to join a conspiracy nominally aimed against the life of Antonio, but actually directed against the Queen, and in 1594 Lopez expiated his crimes at Tyburn. Those who are curious in such matters will be interested to trace in the “Merchant of Venice” the re-appearance of our sumach merchant as Shylock, while the name of Antonio is boldly retained by Shakespeare for his hero (Cf. S. Lee, “The Original of Shylock,” in the Gentleman’s Magazine, 1880). After the arrest of Lopez, his grant was continued to R. Alexander and R. Mompesson (Patent Roll, 36 Eliz., p. 11). In the Charter of the Leathersellers’ Company, dated 1604, “Spanish leather and other leathers dressed or wrought in sumach or bark” are mentioned. In 1660 the duty granted upon imported sumach was fixed at 13s. 4d. per cwt. of 112 lbs., and on dried myrobalans at 1s. 3d. per lb., thus disproving the statement of Prof. Thorold Rogers in his “History of Prices” (Vol. 5, p. 414), that oak bark was the only tanning material used in England at this period. The earliest description known to the writer of the process of sumaching by sewing up the skins into bottles and allowing the fluid extract to penetrate the fibre by pressure, is to be found in 1754 in the “Dictionary of Arts and Science” (Vol. 3, article “Morocco”).

The first step in the degradation of the manufacture of light leathers, though it at first affected the heavy leathers only, was the introduction of the use of sulphuric acid in 1768 by Dr. McBride of Dublin (Phil. Trans., 1778). By substituting a vitriolic liquor for the vegetable acids obtained by fermenting bran, rye, or other cereals, Dr. McBride claimed three advantages: (1) Absolute control over the degree of acidity of the liquor, whereas organic souring was troublesome and uncertain; (2) that the skins were “plumped” better by the acid, and that the danger of injury to skins (by bacterial action) was avoided; (3) that the process of tanning was materially shortened. At all events, the Doctor succeeded in convincing first the Dublin tanners, and shortly afterwards their Bermondsey rivals, of the superiority of his methods, which, as already stated, were intended for heavy leathers only (Encyclopædia Britannica, 1797, article “Tanning”).

Having once established its footing in the tanyard the use of sulphuric acid was soon further extended. With the introduction of aniline dyestuffs about 1870 sulphuric acid came into universal use as a means of clearing the skin before entering the dyebath. The effect of the introduction of the coal-tar colours was to revolutionise the dyeing of leather. Under the old régime of the vegetable dyestuffs the few standard shades of red, blue, olive, yellow, and black were obtained on moroccos mordanted with alum, while bark-tanned calf and sheep skins were, as a rule, left in their natural browns and ornamented by sprinkling or marbling. The wide range of colours offered by the new dyestuffs fascinated the public, which accepted the new leathers without question as to their durability. Librarians began to insist upon accuracy and uniformity of shade, regardless of the methods by which these results were obtained. Yet, apart from the question of durability, it is clear that brilliancy of colour has been purchased at too high a price. Under the old system of dyeing a thin superficial layer of colour was laid over the natural white of the skin, thereby obtaining a variety and depth of colour which is in striking contrast to the dead uniformity of the colours of modern acid-bitten leathers. Hence the reform of the manufacture of the light leathers is supported by æsthetic as well as by practical considerations.

Passing from the domain of chemistry to that of mechanics, the Committee of the Society of Arts has emphasized the need of a return to sounder and less ruinous methods of dealing with leather; but their recommendations are so clearly set out in their Report that it is proposed here to touch upon one point only, viz., the artificial graining of leather. The Committee remark that, whereas many examples of sound sheepskin, dating from the 15th century to the early part of the 19th century, had been brought to their notice, “since about 1860 sheepskin as sheepskin is hardly to be found.” Now, the decoration of leather by the impression of patterns by mechanical pressure had long been known, the lozenge pattern of early russia leather having been effected in the 18th century by means of engraved steel cylinders. But in 1851 it occurred to an ingenious mechanic that, by means of the electroplate process, an exact reproduction of the grain of the higher-priced skins might be communicated to sheepskin or other inferior leather whereby the selling value of the latter would be considerably enhanced (Cf. Bernard’s Patent Specification 13,808 of 1851, and a modification of the same process in No. 2,391 of 1855). From this date, therefore, sheepskin disappears from view only to reappear as imitation morocco, pigskin, or other higher-priced leather. So perfectly does the counterfeit skin imitate the original on the bound volume that the two can only be distinguished with certainty by microscopic examination. Librarians, therefore, must bear in mind that a familiarity with the natural characteristics of the ordinary binding leathers is no safe guide to the character of the leather of a binding. The utmost that can be said is that the leather is either genuine or else a remarkably good counterfeit, a conclusion which, it is hardly necessary to say, is not one of great value in practice.

As might have been supposed, the rapid decay of leather bindings in the 19th century, resulting from a combination of the above malpractices, with the attendant evils of heavy outlay upon rebinding, cropped margins, and ill-matched sets upon the shelves, from time to time attracted the attention of booklovers and bookbinders; but their efforts to determine the causes of the deterioration and to find a remedy have until recently met with very little success. In 1842 the subject was investigated by Professors Faraday, Brande, and others on behalf of the Athenæum Club. This committee is largely responsible for the “sulphur in gas” theory—a theory which was never wholly true, even at a period when the percentage of sulphur in coal gas was much higher than at present (Cf. Journal of the Society of Arts, 1850-59, p. 215), and which now has ceased to have any practical bearing upon the matter. It should be noted that, in 1851, Crace Calvert, the well-known Manchester chemist, came to a different conclusion. After pointing out that decay in leather was observable in libraries, such as the Chetham Library, in which gas had never been used, he stated that the presence of sulphuric acid in leather bindings was attributable to one or more of three causes: (a) to the pollution of the atmosphere by consumption of coal in the Manchester factories; (b) to the action of gas fumes in unventilated rooms; (c) to the use of sulphuric acid by the tanners; and he further expressed his opinion that the seat of the disease would be found in irregularities in the processes of tanning—in other words, that the disease was aggravated rather than originated by these first two causes (Cf. Trans. Society of Arts, Vol. 51, pp. 120-22). Calvert’s views, however, met with very little support. In 1877, at the Conference of Librarians in London, a proposal was made that a committee of librarians and chemists should deal with the matter, but no effect was given to the proposal. Ten years later a series of experiments on the action of gas fumes and heat was undertaken on behalf of the Birmingham Library by Mr. C. T. Woodward (Library Chronicle, 1887, pp. 25-29). Strips of leather exposed for 1,000 hours to the action of gas fumes, at temperatures of 130° and 140° Fahrenheit, showed a mean absorption of sulphuric acid of 1·78 per cent., accompanied by a marked reduction in their stretching capacity and breaking strain. The experiments on the action of heat alone were regarded as inconclusive. Mr. Woodward suggested that the Library Association should undertake the testing of leathers, and that librarians should thereafter employ only leather of a given standard; but once more nothing was done. In the meantime the reputation of leather as a binding material continued to dwindle; one leather after another was tried, found wanting, and excluded from library practice, while various leather substitutes—buckram, art linen, and imitation leathers, gradually took its place. It is due to the efforts of Dr. Parker and Prof. Procter between 1898 and 1900 that the real facts of the case have been brought to light. In the latter years an agitation in favour of standard leather was set on foot by Lord Cobham, Mr. Cockerell, Mr. Davenport, and others, which resulted in the appointment by the Society of Arts of a Committee on Leathers for Bookbinding, the cost of which was met by a grant from the Leathersellers’ Company.

Upon the publication of the first report of the above Committee in 1901 the subject was taken up by the Council of the Library Association, and after several papers had been read at the monthly meetings in London and elsewhere, a Committee was appointed to ascertain how far Members of the Association were prepared to accept a common standard for binding leathers. For this purpose in March 1904, close upon 1,000 circulars were addressed to the libraries of the United Kingdom asking for a statement of their views upon the following proposals, amongst others, viz.: (a) that the Council should appoint an official analyst; (b) that they should publish a handbook giving to members of the Association such information as would enable them to secure sound leather at a reasonable price. The circular meeting with a favourable reception, the Council invited Dr. Parker to draw up a scale of fees for the analysis of leathers, and the scale having been duly approved, Dr. Parker was at once appointed analyst to the Association.

Since the appointment of the Committee abundant evidence has been forthcoming that at last the reform of light leathers for bookbinding and upholstery is now in sight. The efforts of the Committee have been warmly seconded by the Press. In the recently concluded Government binding contracts a clause has been inserted enabling any department to obtain standard leather and rendering the contractor liable to heavy penalties for infringement of the conditions of this clause; yet the price paid for bindings in this leather is only fractionally increased. From the outset the Committee have been assured of the support of the leading firms of leather manufacturers, who have recognised that, if leather is to regain the ground which has been lost, it must be by the adoption of a common standard of manufacture and by the introduction of honest trade descriptions in the retail trade.

Hence where the provenance of the leather is declared and the method of its manufacture supported by a written guarantee from the leather manufacturer, the need for periodical analysis of samples is less urgent. But where the bookbinder is unwilling or unable to state the provenance of his leathers recourse to chemical analysis is the only safeguard. The librarian on his side will materially assist the binder by limiting his demand to leathers of a few standard shades and by abstaining from insisting upon accurate matching to pattern. If the piecing, panelling and lettering of serials is kept uniform, a want of uniformity in the shade of leather is not of much practical moment. In the meantime the librarian should keep a vigilant watch for the following symptoms of deterioration:—

(a) General shabbiness and tenderness of leather, especially at parts where the leather is strained over the cords on the back or edges of the boards. Probable cause: Sulphuric acid.

(b) Red rot in morocco. On friction the leather turns to a red powder. Probable cause: A Persian or East Indian half-bred sheepskin has been supplied in place of goat.

(c) Withering of pigskin accompanied by discoloration. Probable cause: Over “pulling down” of the skin in the “puering” process. If the pigskin has been dyed in a bright shade, acid also is present.

(d) Deterioration and discoloration of smooth and light-coloured calfskins, especially law calf. Probable cause: Use of oxalic acid by the bookbinder to remove grease marks, &c.

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