THE LIVERPOOL AND MANCHESTER PHOTOGRAPHIC JOURNAL. Vol. 1, 1857, p.214
The sheets, after their final removal from the pack, are hung across horse-hair lines to dry; from three to five sheets being suspended together, consequently two only are freely expose to the atmosphere. How far this condition of things may, influence the result I am unable to say. It will also be observed that one sheet is in contact with the horse-hair line, which accordingly leaves a mark across the centre of the surface of all. sheets so situated. These marks, however, disappear to the eye during the carrying on of the subsequent operations. The dry paper, still bibulous, is now quite ready for sizing.
On my first visit to Kent, where the experiments were carried on, I made many enquiries about the materials used in sizing, and also about the amount of boiling to which such materials were submitted; for I knew that the animal tissues and fibres which were capable of yielding a gelatinous size, were also capable of furnishing a different product on the long application of a high temperature. At Hollingsworth's, formerly Whatman's Turkey Mill," I learnt that the hoofs and feet of animals, in a fresh or green condition, were preferred to the dried skins and "pates." commonly employed. The process was to keep such fresh materials for some days in running water to cleanse them, then they were carefully boiled with water, keeping the temperature down as much as possible. The liquid thus obtained was allowed to settle and cool, when the fat would be found on the surface, and the heavy impurities at the bottom of the mass, the intermediate portion being a firm well-looking jelly. This jelly is diluted with hot water to a consistence ascertained by experience, and judged of empirically by its apparent viscidity. Alum, in lump, is then added to the warm jelly in varying proportions. On this point we had no experience. The paper-maker, therefore, added as much as he thought would produce a hard resisting size. The addition of alum in great quantity causes the paper to have a "rattle" on suddenly pulling the opposite corners of a sheet held loosely and diagonally. And as the buyers are supposed to be pleased with this rattle, as affording evidence of the firmness of the fabric, the paper often gets more alum than the conditions for perfect sizing demand. The alum is found to vary very much in quality, but the best kind is of course to be selected. The size, then, consists simply of animal jelly (which is an imperfectly understood substance or mixture of substances) and alum. Coarser sizing materials may contain lime or salt, but these are avoided by good paper-makers. The lime, when present, has been used to remove hair from the skins, and the salt to check putrefaction. This, one thing is certain, that the best paper ever made for the Talbotype process was made at "Turkey Mill," where the size is prepared as above related. This paper, ream by ream, gave, as a rule, fine close black negatives; and it could be made sensitive over night with much stronger solutions of gallo-nitrate than are now recommended. The development could be deferred until the same hour the next night. It could fully be depended upon for twenty-four hours even, be it remembered, when washed over with comparatively strong solutions of gallo-nitrate.
This paper was used successfully by the Rev. Calvert Jones, about 1844, at Malta, in very hot weather, and also in the East by the Rev. Mr. Bridges. It is strange to relate that such paper has never been obtained since, even from the same mill, and that is why I dwell so much upon it at this moment. Could we get such paper again .with certainty the Talbotype would take a new start. The only thing that could compete with it. would be the transfer process applied to collodion, but that will always be a delicate, if not a difficult operation for the amateur to perform while on a tour. I trust these "jottings" of mine may assist in bringing about a good process for the manufacture and preparation of photographic paper, for. it is certain that at present all the paper makers are working in the dark as far as principles are concerned. Cansons, the French makers, are, I am told by Dr. Warren de la Rue, noted for the insolubility of their paper-size, but unfortunately for us they will not disclose their process, consequently there can be no interchange of ideas between chemical photographers and themselves.