OZOTYPE is a modification of the carbon process designed with the object of dispensing with the actinometer and the transfer which is necessary in carbon printing to produce pictures in the correct position as to right and left. There is a distinctly visible image. The picture is produced upon the paper which forms its support in the correct position as to right and left. No safe edge is required. The pigment plaster (which is a modification of carbon tissue) is not rendered sensitive to light, and therefore keeps indefinitely.
Although ready sensitised papers are supplied by the inventor of Ozotype for the convenience of home and continental consumers, it is advisable in the case of colonial and Indian workers to sensitise the sized papers specially prepared for Ozotype.
This operation may be performed in diffused daylight, but it is absolutely necessary that the drying be carried out in the dark. The tools required are very simple. A yard of fine flannel, some cotton wool, a few yards of soft muslin, drawing or dark-room pins, sensitising solution, gum solution (one part to three of water) or fish glue solution (one in four).
A sheet of sized paper supplied by the Ozotype Company measures 30 in. by 15 in. This area requires two drachms of the sensitising solution. Lay the paper on a larger sheet of any 'clean paper, and pin the four corners down with drawing or dark-room pins.
Take about a square foot of the flannel and as much of the cotton wool as can be conveniently grasped in the hand. Wrap the flannel round the cotton wool so as to form a rubbing-pad.
Pour into a graduated measure exactly 120 minims or two drachms of the sensitising solution. Add to this about four to eight drops of gum or fish glue solution. Hold the glass of sensitising solution in your left hand, and in your right hand have the coating pad ready.
Throw the contents of the measure on to the middle of the paper, and without losing any time spread the pool all over the surface of the paper by means of the coating pad with a circular motion until the paper is quite covered. Then writh vertical and horizontal strokes increasing in lightness the paper should be evenly coated. Any remaining streaks can be obliterated by lightly passing a piece of the soft muslin across them. Hang the coated paper in a well ventilated dark-room to dry, which will take about fifteen minutes. Cut the paper into the required sizes in gaslight (not diffused daylight), with a long pair of scissors. When dry the paper is ready for printing.
Any good negative is suitable. Expose to daylight until the details in the high lights are very faintly visible. The duration of the printing is the same as for platinotype— that is, about one-third the time required for P.O.P. printing.
The print should be washed as soon as possible after exposure. The extent of washing is a very important point. It should be carried out in cold running water, and should not be continued after the margins covered by the rebate of the printing frame are quite clean and white. The temperature of the washing water has an important influence upon the extent of washing. In summer when the temperature of water is from 650 to 750 Fahr., the margins of the print should be quite clean in four to six minutes. In winter time, however, with water at 350 to 400 Fahr. the washing will probably take fifteen to twenty-five minutes. In spring and autumn six to ten minutes will probably be sufficient.
This operation can be carried out while the print is wet from the washing water, or the print may be dried and the pigmenting operation deferred to any convenient time within a fortnight or three weeks if the dried print is preserved in a dark place free from damp. The pigmenting operation consists in soaking a piece of pigment plaster for a short time in a very dilute solution of an acid and a reducing agent, and bringing it in contact with the print.
Make up a stock solution as under :—
Powdered alum . . 1 ounce.
Pure sulphuric acid . 3 drachms or 180 minims.
This will keep indefinitely, and the bottle should be labelled S.A. (stock acid).
For use make up one of the following solutions :—
for strong and
S. A. solution
8 to 10 drams
Pure ferrous sulphate
A is suitable for prints from contrast negatives and for delicate effects for small work on well-sized paper. B is suitable for prints from any good negative.
C is suitable for large work where boldness and strength of colour are required and for prints from weak negatives.
N.B. - The larger the proportion of S.A. solution the stronger and bolder the effect.
Another variation of the acid-reducing is given at the end of this article. The ferrous sulphate bath, however, has the advantage of rapidity in action, the picture being ready for development in about half an hour after pigmenting without any preliminary cold-water bath.
Pour the acid solution into a porcelain dish a size or two larger than the print to be pigmented. Place another dish alongside of this containing tepid water.
Take the pigment plaster and immerse it face downwards under the surface of the acid bath and begin to count 30 seconds (40 seconds in very cold weather). In the meantime take the print and draw it face and back along the surface of the water, removing all air-bells with the finger. At the expiration of about 20 seconds turn the plaster face upwards in the acid bath, and when the 30 or 40 seconds are up, place the print (which may be conveniently held in the hand after the dip in the water) face downwards, on the surface of the acid bath and draw it gently across the surface ; lifting it right out of the dish. Immediately replace it in the bath, and grasping the underlying plaster by the two top corners and holding the print by the thumbs bring the two pieces, clinging together, out of the bath and squeegee them gently together, plaster uppermost, upon some smooth non-absorbent surface such as a papier-mâché board or sheet of glass. Then insert the plastered print between clean blotting-paper, passing the hand heavily over the outside of the blotting-pad. It is most important that the print should not be kept in the acid bath a moment longer than is absolutely necessary. The operation of bringing the print into contact with the plaster can be easily performed in 10 seconds, and should not occupy a much longer time. The plastered print is ready for development in 30 to 40 minutes.
When the ferrous sulphate bath is used the development should take place in 30 to 45 minutes after squeegeeing. This operation is carried out in a similar manner to carbon printing. An iron tank with gas or spirit burner may be used, or hot water from a kettle may be poured into a dish. The temperature of the development water should be from 1100 to 1150 Fahr. for the removal of the plaster backing. Place the plastered print in the hot water and wait for about a minute. Try by a sliding movement of the thumb and finger at the four corners if the gelatine is sufficiently soft to allow of the easy separation of the paper. Do not begin to strip until this is the case, leave it a little longer if necessary. Strip the plaster backing off from one corner with a steady unbroken pull, always keeping it under the surface of the water. After the removal of the plaster the print is still covered over with pigmented gelatine, and with further treatment with hot water the picture develops more clearly, and can be allowed to remain floating on the surface of the bath, or the development can be accelerated by holding it against a sheet of zinc (the size of the paper) and moving it up and down under the surface of the water. A small tin:
For bold effects
Softness and delicacy
Glacial Acetic Acid
10% Sulphate of Copper
In using the hydroquinone bath the following points should be attended to :—(1) The printing out should not be carried quite so far as when the iron bath is used. (2) After squeegeeing, the plaster and print should be kept a longer time in contact, say 1^ hour or any time after the print is dry. (3) Before development the plastered print must be immersed in cold water for half to one hour mug will be found useful for clearing high lights by gently pouring the warm water over the plaster. Of course the temperature of the water can be raised for overprinted pictures. Should the development be still difficult it is a good plan to place the picture for a few minutes in a bath consisting of Warm water .... 40 oz. Hydrochloric acid 1 drachm, and continuing the development in the warm water.
The Ozotype picture is softer than the ordinary carbon print during development, and sticks more firmly to the support, so that retouching with a brush is an easy matter. Clouds can be easily made and lights emphasised with a touch of a soft camel-hair brush during development. Shadows can also be accentuated by painting them over with methylated spirit in the early stage of development.
An acid reducing-bath containing acetic acid and hydroquinone has proved very successful in some hands.