Re: Oil printing FINALE
Hi Judy! Certainly enough for now! I'll go see if I can get into the Leiden Library one time, to see if they have a decent alt collection of journals to go through... Learning from the old masters somehow seems very interesting. Just to 'feel' the 'oldness' of the procedure, in stead of using one of the books from a few years ago (though still very informative and usually already very precise!)
DirkJan 2008/9/29 Judy Seigel <jseigel@panix.com>
"PHOTOGRAPHY, Its Principles and Practice," by C B Neblette, FRPS, 4th edition EIGHTH PRINTING !!! probably has more on this topic than is cited below (but the index stinks); the copyrights are from 1927 to 1947.
On page 28, in a section titled "Development of the Oil, Bromoil and Powder Processes," we find:
A 2nd process was worked out & patented by Poitevin in which a bichromated gelatin film without pigment was exposed under a negative. This gelatin film, on exposure to light under the negative, became more or less insoluble in various portions according to the gradations of the negative. When immersed in water, the soluble gelatin absorbs water & becomes so charged with water that it will repel a greasy ink, while the shadows, being insoluble, do not absorb water & will accept the ink. Accordingly when a roller charged with greasy ink is passed over the print, an image is formed in greasy ink which adheres to the shadows but not to the highlights of the print.
Etc.
Then on page 674, under Resinopigmentype:
"In this pigment process, developed by Prof. Rudolph Namias, of Milan, a gelatin coated paper is sensitized in potassium or ammonium bichromaate, dried & exposed under a POSITIVE [emphasis added] transparency. It is then placed in cold water for several hours to eliminate the excess bichromate & transferred to water at 50 degrees C (122 F) to produce a brief image in differentially hardened gelatin. A resinous pigment impervious to water (as gum dammar, shellac, bitumen or dragons blood with a suitable pigment) is then applied with a brush. The pigment adheres to the swollen portions of the image (after the surface moisture is removed) but not to the hardened portions, thus forming a pigment image...."
Finally, "Cassell's Cyclopedia of Photography" ["Illustrated by 24 full-page plates in colour & half-tone and by hundreds of line drawings in the text," it says, but this edition is too, too coyly ENTIRELY undated, tho I recall reading somewhere that it was circa 1913] has a tightly spaced, small-type column on PIGMENTING, including brushes, applicable it seems to both oil printing and bromoil.
That's on page 411.
Enough?
J.
|