[Alt-photo] Poitevin 1855

Peter Friedrichsen pfriedrichsen at sympatico.ca
Fri Sep 23 03:13:46 UTC 2016


Here is the British patent I found once in a book. Never could find the 
French one which does have some variation apparently

==========================

Specification of the Patent granted to ALPHONSE LOUIS POITEVIN, Civil 
Engineer, of Paris, in the French Empire, for Improved Photographic 
Printing.—Dated December 13, 1855. To all to whom these presents shall 
come, &c., I print photographically with ink of a greasy nature on 
paper, lithographic stone, metal, glass, wood, or other suitable 
material, in the following manner :—I apply upon the surface which is to 
receive the design one or more layers or films of a mixture, of equal 
parts of a concentrated solution of albumen, fibrine, gum arabic, 
gelatine, or similar organic substance, and a concentrated solution of a 
chromate or bichromate of potash, or of any base which does not 
precipitate the organic matter of the first solution. This single or 
compound layer or film is then dried if the photo-graphic impression is 
to be produced by contact ; or it may be used in a moist state when the 
photographic impression is to be produced in the camera obscura. In 
producing the impression by contact, the surface is covered with a 
photo-graphic negative picture, or an engraving, or other trans-parent 
or partially transparent object, or screen, and then exposed to light, 
as in the ordinary photographic process. After a sufficient exposure, if 
the surface has become dry or has been used in a dry state, it is 
moistened with water by means of a sponge, and, while moist, the greasy 
ink or matter is applied to the surface by a ball or dabber, or by a 
roller or press, or otherwise, and it will be found to adhere to those 
parts only which have been affected by the light. Thus, if the screen 
employed be a negative, having the lights and darks reversed, the print 
will be a positive, with the lights and darks correct ; and, if the 
screen be a positive, the print will be a negative. The print may be 
retained on the surface on which it is first produced, or it may be 
transferred or printed upon paper or other suitable material, and the 
operation repeated. I thus obtain a design upon lithographic stone, or 
other suitable material, from which I am enabled to multiply impressions 
by the method of lithographic printing by inking the moistened surface 
with a greasy ink. I apply various liquid and solid colours upon paper, 
cloth, glass, and other surfaces, by mixing such colours with the 
aforesaid mixture of a chromate or bichromate with organic matter, and 
applying this new mixture or combination to the paper or other fabric or 
surface. The photographic impression is produced upon this prepared 
surface by the action of light passing through a negative photographic 
picture, or an engraving, or other suitable object, or screen, or in the 
camera obscura, and it is then washed with a sponge and a large quantity 
of water. The albumen or other organic matter is rendered insoluble at 
the parts where it has been acted upon by the light, and the design is 
thus produced in the colour which has been employed. Mixtures containing 
different colours may be applied to different parts of the surface, 
corresponding to different parts of the negative or screen employed to 
produce the photographic impression. A design in several colours may 
thus be produced. The proportions of the materials may be varied. Having 
now described the nature of my said invention, and in what manner the 
same is to be performed, I wish it to be understood that what I claim 
is,—First, the mode of printing in the manner of lithography, by 
moistening and inking with a greasy ink a lithographic stone, or other 
suitable surface, prepared with chromatized albumen, fibrine, gum, 
gelatine, or similar organic sub-stance, and on which a photographic 
impression or effect has been produced in manner hereinbefore described. 
Second, the mode of printing upon paper, cloth, glass, or other suitable 
surfaces, by applying to them a mixture of liquid or solid colours with 
the aforesaid chromatized albumen or other organic matter, and exposing 
to light, as hereinbefore mentioned, and afterwards washing away those 
portions of the mixture which have not been acted upon by the light, as 
hereinbefore described.—In witness, &c. ALPHONSE LOUIS POITEVIN.

=========================

Peter


On 22/09/2016 3:17 AM, Alberto Novo via Alt-photo-process-list wrote:
> Anyone has the transcription (not simply any description of the process) of the Poitevin UK patent #2816 or of the French #24592 about photolithography?
>
> Alberto
> _______________________________________________
> Alt-photo-process-list | altphotolist.org



More information about the Alt-photo-process-list mailing list