Report of the Committee on Leather for Bookbinding : with four appendixes ... / Society for the Encouragement of Arts, Manufactures, & Commerce.

  • Royal Society of Arts (Great Britain)
Date:
1901
Catalogue details

Licence: In copyright

Credit: Report of the Committee on Leather for Bookbinding : with four appendixes ... / Society for the Encouragement of Arts, Manufactures, & Commerce. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    18/22 (page 16)
    3. Bookbinding. We leave the mechanical art of bookbinding to other members of the Committee, but there are several chemical points which we must touch upon. The use of oxalic acid for wash- ing backs of books, or of leather for bookbind- ing, is fatal to their durability. Vinegar, even in its pure state, is injurious, but many book- binders use a very crude wood-vinegar, con- taining tarry products, which make its use still more detrimental to the leather? The presence of sulphuric acid in the vinegar used should be guarded against. The sprinkling of leather, with ferrous sulphate (green vitriol), either for the production of “sprinkled” calf or “tree” calf, must be most strongly condemned, as the iron combines with and destroys the tan in the leather, and free sulphuric acid is liberated which is still more destructive. Iron acetate or lactate is somewhat less objectionable, but probably the same effects may be obtained with aniline colours without risk to the leather. The egg-glaires used by bookbinders cer- tainly tend to preserve the leather from external atmospheric influences. It is, however, a debatable question whether the glaire does not interfere with the pliability of the leather at the joints, and at the portion of the leather which bends when the book is opened. This also applies to the use of resinous varnishes as preservatives. We have examined samples of the pastes which are used by bookbinders, and have not found anything which would be likely to be detrimental to the skins ; but it is important that the paste should be used in a fresh con- dition, otherwise it is liable to undergo an acid fermentation, and to favour the growth of injurious moulds and bacteria. The stretching of leather tightly over books in a wet condition has the same bad effects as dry- ing nailed on boards, but in an almost greater degree, and should be strongly condemned. 4.—Preservation of Books. Much light has been thrown on the influence of various outside conditions existing in libraries on the durability of leather, by a series of very careful experiments made by the Committee. These experiments prove conclusively that the acid fumes of burnt gas are the most fatal of all the influences to which bindings arc ordinarily exposed, producing what has been described as “red decay,” on every sort of leather to which they have had access, the effect being most marked on the East India tannages, and other leathers made with tannins of the catechol class ; and least so upon these with sumach, and other tannins such as myroba- lans, which are known to be pyrogallol derivatives, while oak-bark occupies an inter- mediate position, both practically and chemi- cally. It was shown that 30 days’ exposure to the fumes of a very small gas jet rendered East India leather (tanned with turwar bark) perfectly rotten, so that the surface could be scraped off with the finger nail, while on leather tanned with sumach it had com- paratively little effect. Similar experiments were made with exposure to sunlight during 30 days of the past summer, and in this case again, the leathers were affected in the same order ; turwar, quebracho, larch bark, and gam- bier being among the worst ; and sumach and myrobalans the least affected, while oak-bark as before occupied an intermediate place, being somewhat darkened but comparatively little tendered. It was found that serious effects, very similar to those of light, were produced by exposure during 30 days to air at a tempera- ture not exceeding no°to 120° Fahr., dry air being apparently slightly the most deleterious. Some attempts have been made to determine the effect of light transmitted through glasses of different colours, and they point to the fact that blue and violet glass pass light of nearly as deleterious quality as white glass ; while leathers under red, green, and yellow glasses were almost completely protected. These statements are true not only of East Indian tanned skins but of those tanned with sumach, but the latter were much less affected, even by the blue, white, and violet light, again demon- strating the greater power of resistance of sumach tannage. There can be no doubt that the use of pale yellow or olive-green glass in library windows exposed to direct sunlight is desirable. A large number of experiments have been made on the tinted “cathedral” glasses of Messrs. Pilkington Bros., Limited, with the result that Nos. 812 and 712 afforded almost complete protection during two months’ exposure to sunlight, while Nos. 704 and 804 may be recommended where only very pale shades are permissible. The glasses employed were subjected to careful spectro- scopic examination, and to colour-measure- ment by the tintometer, but neither were found to give precise indications as to the protective power of the glasses, which is no doubt due to the absorption of the violet, and especially of the invisible ultra-violet rays. An easy method of comparing glasses is to