Improved Solutions for Toning Photographic Prints.
Year: 1892

page_text: Date of Application, 5th Oct., 1892
Complete Specification Left, 4th July, 1893-Accepted, 16th Sept., 1893
PROVISIONAL SPECIFICATION.
Improved Solutions for Toning Photographic Prints.
I, RUPERT GREVILLE WILLIAMS, of Greenfield House, Heywood, Manchester,
Lancashire, Manufacturing Chemist, do hereby declare the nature of this invention
to be as follows:-
My invention relates to improvements in processes for touing photographic
prints, and its object is to replace the expensive salts of gold, platinum, &c., which
have hitherto been generally used, by substituting potassium, sodium or ammonium
sulphide.
The prints toned by such processes are very permanent and this permanence is
the necessary result of the chemical reaction which takes place.
The preparation which I have found to be generally most useful for the purpose
of the present invention consists of a mixture of 40 parts by volume of ammonium
sulphide and 600 parts of strong ammonia liquor which is then made up to
2000 parts by adding water.
The method of using the improved toning solution prepared as above described
will be understood from a description of the way in which it is applied to a
gelatino-chloride print which has been produced in the usual manner.
After the print has been washed in cold running water for about half an hour, it
is immersed in a mixture of about 1 volume of a saturated solution of sodium
hyposulphite and 3 volumes of water containing a small quantity of ammonia. The
print rapidly turns a bright canary yellow, and in a few minutes, is fixed, and may
therefore be toned in a bright light. All traces of the hyposulphite must however
first be removed by washing. It is next transferred to a vessel containing 1 part
by volume of the toning solution above described and 50 parts of water, in which
it is moved to and fro for a few minutes, by which time it will have assumed a tone
varying from orange-brown to chocolate-brown, according to the length of the
immersion. The process just described must not be carried too far, otherwise
unpleasing tones may be produced. The colour of the print after it has been dried
is quite different to that which it had while wet. This being the case, it is
advisable to keep a print which has been satisfactorily toned according to the
present invention, and use a wetted portion of it as a guide. When the print
undergoing the process of toning presents the same appearance in point of colour
as the guide, it is removed from the bath, washed thoroughly, and then drained
and dried. An additional alum bath to harden the film may often be used with
advantage.
It is only on gelatino-chloride papers that results that are in every way
satisfactory have been hitherto obtained.
Dated this 4th day of October 1892.
PHILLIPS & LEIGH,
Agents for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improved Solutions for Toning Photographic Prints.
I, RUPERT GREVILLE WILLIAMS, of Greenfield House, Heywood, Manchester,
Lancashire, Manufacturing Chemist, do hereby declare the nature of this invention,
and in what manner the same is to be perforined, to be particularly described and
ascertained in and by the following statement :-
My invention relates to improvements in solutions and process for toning
photographic prints and is applicable more particularly to that class of prints
which are known as gelatino chloride, irrespectively of their having been printed
from the negative upon gelatino-chloride printing out papers, gelatino-chloride
printing out slides or gelatino-chloride printing out opals. I mean by the foregoing
term "gelatino-chloride printing out," a paper, a slide or an opal or other suitable
surface prepared with a gelatino-chloride emulsion.
One of the objects of the invention is to replace the expensive salts of gold,
platinum and the like metals, which have hitherto been generally used, by
potassium, sodium or ammonium sulphide.
The prints toned by my improved process are very permanent and this permanence
is the necessary result of the chemical reactions which take place during the said
process.
The solution which I have found to be generally most useful for the purpose of
the present invention, consists of a mixture by volume of 40 parts of either
potassium, sodium or ammonium sulphide and 600 parts of strong ammonia liquor,
which mixture is then made up to 2000 parts by the addition of water.
The proportions given in the preceding paragraph may be varied to any extent
without departing from the invention, subject to the two following limiting
considerations.
With reference to the proportion of the sulphide :-The smaller the proportion,
the longer will be the time which the process of toning will take.
With reference to the proportion of the ammonia-As its function is only to
keep the bath alkaline independently of the alkalinity imparted to it by the sulphide,
any proportion capable of so keeping the bath alkaline, will meet the requirement
of my invention, and on the other hand, excess of ammonia will not impede the
process of toning, although too much will soften or blister the printing out.
The method of using the improved toning solution prepared as above described
will be understood from a description of the way in which it is applied to a
gelatino-chloride print which has been obtained in the usual manner.
After the print has been washed in cold running water for about half an hour, it
is immersed in a mixture of about one volume of a saturated solution of sodium
hyposulphite and 3 volumes of water containing a small quantity of ammonia. The
print rapidly turns a bright canary yellow, and in a few minutes is fixed. All
traces of the hyposulphite must then be removed by thorough washing, when the
print is transferred to the toning bath which is made up by adding one part by
volume of the toning solution above described and 50 parts of water, in which it is
moved to and fro for a few minutes, by which time it will have assumed a tone
varying from orange-brown to chocolate brown, according to the length of the
immersion. The process just described must not be carried too far, otherwise
unpleasing tones may be produced. The colour of the print after it has been dried
is quite different to that which it had while wet. This being the case, it is
advisable to keep a print which has been satisfactorily toned according to the
present invention and use a wetted portion of it as a guide. When the print
undergoing the process of toning presents the same appearance in point of colour
as the guide, it is removed from the bath, washed thoroughly and then drained and
dried. An additional alum bath to harden the film may often be used with
advantage.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
1. The hereinbefore described process of toning gelatino-chloride photographic
prints.
2. In toning solutions, the combination therewith of alkaline sulphide solutions
in place of solutions of gold, platinum, or the like metals, as set forth.
Dated this 4th day of July 1893.
PHILLIPS & LEIGH,
22, Southampton Buildings, Chancery Lane, London, W.C.,
Agents for the Applicant.