By THOMAS MANLY, F.R.P.S.
Ozobrome is a very easy step from silver printing to carbon printing. An Ozobrome picture is a carbon picture, but it is produced in a much, easier and more convenient way. A bromide print is used instead of a negative, and the printing is done, not by the influence of light, but by chemical action.
The process is especially useful when making carbon enlargements, as a bromide enlargement takes the place of both the transparency and the enlarged negative, thereby saving considerable expense.
Unlike the carbon process the first transfer presents the image in its true position, as regards the right and left, thus doing away altogether with the labour of double transfer.
The working of the process can be carried out by any amateur photographer in the evening, the only preparation necessary being the getting ready of a few dishes. The carbon tissue, or pigment plaster, as it is called in this process, is not sensitized and dried as in the carbon process, but merely soaked in the patented Ozobrome pigmenting solution, then dipped into a very weak acid bath for a few seconds and applied to the surface of the wet bromide print The two papers are pressed together with a squeegee and left for about fifteen minutes for the chemical action to take place.
Thomas Manly, F.R.P.S.
The print is now ready for development in warm water, or the two papers may be separated in cold water, and the impressed plaster squeegeed upon another support, thereby allowing the bromide print, after being re-developed, to be used again for the production of further Ozobrome copies.
Apart from a good bromide print or enlargement only the following materials are required : (1) Ozobrome Pigment Plaster - a special paper coated with pigment and gelatine which forms the image of an Ozobrome Print.
(2) Ozobrome Transfer Paper, which supports the image in its final state.
(3) Ozobrome Pigmenting Solution used to sensitize the Pigmenting plasters.
(4) A special acid bath.
It will be seen, therefore, that the extra outfit required by anyone wanting to work this carbon process without daylight does not entail any elaborate outfit.
First as to the Bromide Print. Any good print, on any paper, will suffice from which to make our Ozobrome, but if a number of prints are desired, it is advisable to use the specially strong bromide paper introduced by Messrs. Illingworth for the purpose. Either Amidol or Metol Quinol are suitable developers for the Bromide print or enlargement. The only suggestions that I may make regarding the Bromide print is that when fixing it an Acid Fixing Bath should be used if the best and most brilliant Ozobromes are desired.
Supposing we have our Bromide Print, then get ready the following baths : PIGMENTING BATH.
Ozobrome Patent Concentrated Pigmenting Solution as sold .. 1 part. Water . . . . .. . . .. 4 parts.
ACID BATH. No. 1, for soft effects.
Chrome Alum (recryst.)
No. 2, for strong effects.
Chrome Alum (recryst.)
(1) Place the Bromide print in water to soak.
(2) Immerse the pigment plaster in the Ozobrome pigmenting solution (working strength) until it flattens out, which will take in summer about 1 1/2 minutes and in winter 2 1/2 minutes.
(3) Remove the soaked plaster from the pigmenting solution and after draining for 15 seconds immerse it in one of the above acid baths for a certain definate number of seconds for certain groups of colours, as specified below.
(4) Transfer the plaster from the acid bath to the dish in which the bromide print is soaking, draw the plaster across the surface of the water to remove any superfluous acid solution, and bring the two papers into contact, withdraw them, clinging together, and squeegee into contact.
(5) Leave the adhering papers on blotting paper for 15 or 20 minutes for the chemical action to take place. Either of two methods are now available for completing the operations.
Method No. 1. (In which the bromide print forms the base of the picture). Place the adhering paper (after being in contact the requisite time) direct into warm water at 102 to 108 deg. Fahr., and after removing the plaster backing, turn the picture face downwards on the surface of the warm water and give it a to and fro or rubbing motion, which will remove most of the soluble gelatine, a dash or two of the warm water against the picture will complete the development. The plaster should be cut smaller than the bromide print for this method. Then fix in a 10 per cent, solution of hypo, for ten minutes, in order to remove the bleached silver image that is beneath the pigment image, and afterwards wash for 10 minutes.
Method No. 2. (In which the impressed plaster is transferred to a separate support, leaving the bromide print available for further use.) Slide a piece of transfer paper under the surface of clean water in a dish. Separate the plaster from the bromide print by a steady pull from one corner ; place the bromide in a separate dish of water, and bring the impressed plaster into contact with the transfer paper under water. Remove and squeegee together firmly. Place between blotting paper under slight pressure for five minutes (not much longer), then develop in hot water as described in No. 1 Method. The plaster for this method should be larger than the bromide print and all Ozobrome plasters are supplied for full size.
The bleached bromide print is re-developed, after being carefully washed, in any Amidol or Metol-Hydroquinone developer, full strength but without any Potassium Bromide. This operation may be carried out in ordinary light or daylight, and no fixing is required. The print, after washing and drying, may be used again for making more Ozobromes.
TIME OF IMMERSION OF THE PIGMENT PLASTER IN THE ACID BATH.
The time that the plaster (impregnated with the pigmenting solution) should be immersed in the acid bath is dependent upon the colour of the plaster - the colours being divided into three groups, viz. : Colour Group A. - No. 58, Engraving Black. No. 60, Warm Black. No. 97, Blue Black. No. 75, Sepia. No. 51, Portrait Brown. No. 68, Dark Blue. No. 65, Sea Green. No. 59, Platinum Black. No. 50, Standard Brown. No. 76, Willesden Sepia, and similar colours containing black pigment.
Colour Group B. - No. 77, Warm Sepia. No. 88, Nut Brown. No. 70, Red Chalk. No. 83, Terra Cotta. No. 87, Italian Green, and the transparent Browns.
Colour Group C. - No. 82, Violet. No. 67, Milan Green. No. 84, Lilac. No. 85, Carmine. No. 86, Light Blue, and similar bright transparent colours.
The times of immersion are : Group A, 15 seconds. Group B, 10 seconds. Group C, 7 to 8 seconds.
A shorter immersion of a few seconds will produce a stronger result, while a longer immersion will give a more subdued effect.