Mechanical an Useful arts. Anastatic Printing.

The Year-Book of Facts in Science and Art Exhibiting the Most Important discoveries and Improvements of the past year, in mechanics and the useful arts; natural philosophy; electricity; chemistry; zoology and biology; geology and geography; meteorology and astronomy. By John Timbs, editor of "the Arcana of Science and Art." London: David Bogue, Fleet Street, MDCCCXLIX (1849)Mr. H. E. Strickland, M.A., of Oxford, in conjunction with Mr. Delamotte, who has established an Anastatic Press in the above city, has succeeded in transferring and printing from drawings made on paper with lithographic chalk. He made a hasty sketch on common drawing paper (of good quality, but not very smooth surface), and sent it to Mr. Delamotte's press. Within an hour, Mr. Strickland received a perfect fac-simile of the original drawing, not to be distinguished from a lithograph. Further experiments will be required to prove whether this method can supersede the finer branches of lithographic drawing; or, in other words, whether paper can be made with a surface as finely and uniformly grained as that which is produced on the stone. But for less delicate and elaborate works there can be no doubt that the antistatic process has two advantages over lithography: first, we dispense with the cost and inconvenience of transporting and using heavy stones. The traveller may now fill his portfolio with sketches made in the field, with lithographic chalk on paper, and may afterwards print of as many copies of these sketches as he pleases. And secondly, the drawings do not require to be reversed, or even copied, — a great saving of the artist's time and labour. — Athenæum, No. 1059. A correspondent of the Athenæum, No. 1060, suggests that if India paper, or, as it is sometimes called, Chinese paper, of the best quality, be mounted on soft plate-paper (by pressing the two together, while damp, through a lithographic press, the India paper being in contact with the blank surface of a lithographic stone, which has been properly grained as for a fine lithographic chalk drawing, precisely as India paper impressions of lithographs are taken), and afterwards dried under a slight pressure, to preserve the flatness of the double sheet, it will be found that the surface of the India paper has had a clear sharp grain communicated to it by the grain of the stone, of which it will be the exact counterpart — but little, if at all, inferior to it — adapted to receive drawings done with lithographic chalk, that may vie in finish, force, and delicacy, with highly-finished drawings done on the stone. These drawings so executed may, as Mr. Strickland proposes, be subjected to the anastatic process; and, adds the writer, "I have little doubt that very beautiful and highly-finished works may most conveniently be produced in this manner. I may observe that I have frequently had paper prepared in this way, as I consider it a most agreeable preparation for pencil and chalk drawings of the ordinary description; and I have found that it would be comparatively inexpensive, as it may be done by any lithographic printer." Mr. Strickland has since tried various kinds of paper as a medium for the lithographic chalk, and finds that the so-called metallic paper (prepared for metallic pencils) makes the nearest approach to the effect of lithography. Fine drawing paper, smooth but not glossy, is the next best material. Mr. Delamotte has found India paper too tender a substance for transferring to zinc. For fine subjects it is essential that the lithographic chalk be of a hard quality and cut to a fine point. The papyrographs thus produced appear to the eye like lithographs; but, when examined by a lens, they exhibit a different effect, in consequence of the surface of paper consisting of horizontal fibres, while that of a lithographic stone is made up of small conical points. That the latter structure might be given to paper by mixing some finely-powdered mineral matter with the fibrous pulp. Calcareous substances, however, will effervesce with the acids used in transferring, and siliceous ones would be too rough and gritty. Some hard aluminous matter, such as powdered slate, or brick-dust, if mixed in due proportion with the paper, would probably enable us to produce the effect of lithography without the use of stones.

Ei kommentteja :