FABRICS, PRINTING ON Fabrics already sensitised for the bromide and platinotype processes may be purchased, and they are used in the same way as bromide and platinotype papers. Fabrics are easily pre pared for photographic printing, and the blue print process is perhaps the simplest. The fabrics mostly employed are cottons, linens, silks, nainsooks, etc., but silk that has been weighted with mineral matter is unsuitable ; the finer the material the better. The fabric needs to be thoroughly washed in hot water, ironed, and, to prevent the image from sinking into the material, it should then be well sized, a suitable size being— Arrowroot . . 8o grs. 8 g.
Gelatine . • • 33 ,, 3'3 ,, Alum . . . i 8 „ 1.8 „ Water to . . . 20 oz. I,000 ccs.
The fabric is immersed in this solution for about five minutes, pinned down on to a flat board, and dried before a fire, it being then somewhat stiff. The ammonio-citrate and ferricyanide sensitising solution (see " Blue-print Process ") is then brushed over it, and, after drying, it is ready for printing upon. Printing, washing (fixing), etc., are exactly as described for blue prints upon paper. The printed fabric will not withstand washing with soap and water, as the alkali destroys the blue image.
In order to get the best and brightest of blue prints upon fabrics, it is necessary to use a negative with strong contrasts—that is, one with clear shadows and dense high lights, and the negative should show broad effects of light and shade rather than an abundance of fine detail.
A process for the replacing of the blue ferro prussiate image by various dyes was published in 1898 by Stewart E. Carter. Bleached cotton or linen is brushed over with a ferro-prussiate sensitiser, made as follows : A. Ferric ammon. citrate 164 grs. 164 g. Distilled water to . I oz. 50o ccs.
B. Potass. ferricyanide . 164 grs. 164 g. Water to . . i oz. 500 ces.
A and B are mixed in equal parts. The sensi tised fabric is exposed and washed just as a print upon paper. The blue print is next immersed in a weak solution of caustic soda (5 grs. to 1 oz. of water) for a few minutes, then washed in hot water, and placed for three minutes in a solution of 13 grs. of sodium phosphate in io oz. of water at a temperature of 17o° P. (about 77° C.). This is followed by washing, first in cold water and then in hot water, after which the print is ready to receive the dye. A weak gelatine solution is made (glue size 24 grs., water io oz.) and heated to 16o° F. C.), and the prints moved about in it for about three minutes ; from 3 to 5 grams per litre (1.5 to 2.2 grs. per ounce) of dinitroresorcin (resorcin green) is added, and the temperature raised to 18o° F. (82° C.). As soon as the shade is considered full enough for a strong picture, remove to boiling water to wash out all unfixed dye. The high lights (whites) are next cleared in a bath of neutral soap (used at a temperature of 16o°F., 70C), and the print again washed
in hot water and finally in cold. Other dyes may be used in place of the green named. Gallo-cyanine gives blue and violet ; alizarin gives purple, and also a brown sepia. The original blue print may be toned, but the dye method, although rather troublesome, gives the more pleasing effects.
Carbon prints may be transferred to any kind of fabric. This must be washed, dried, ironed, and given several coats of the following sizing mixture, allowing to dry after each coat : Cooking gelatine . 2 02. 133 g.
Sugar . . 1 „ 66.5 „ Glycerine . . 1 „ 66 ccs.
Chrome alum . . 15 grs. 2 g.
Barium sulphate . 4 oz. 266 „ Water to . . . 15 „ x,000 ccs.
Dissolve by heat and mix thoroughly. Transfer the carbon tissue thereon in the usual way. (See " Carbon Process.") Fabrics can be sensitised and used as ordinary P.O.P. First soak the washed and dried fabric in the following size for about three minutes : Gelatine . . . Ioo grs. 10 g.
Common salt . . xoo „ 10 , Magnesium lactate . Ioo „ 10 , Water to • . . 20 oz. 1,000 CCS.
Dissolve by aid of heat and then well mix ; after coating the fabric allow it to dry thoroughly. The sized fabric is then sensitised by soaking for three minutes in— Silver nitrate . . 25 grs. 52 g.
Distilled water to i oz. i,000 ccs.
The fabric is next immersed for one minute in— Citric acid • • grs. 5 g.
Sugar . • 5 ), Water to . . . 20 „ 1,000 ccs.
and dried in the dark. The sensitive fabric is then printed upon, toned, fixed, and washed exactly as ordinary P.O.P.
An easier method of coating fabric with a silver solution is the following : A salting or sizing bath is first made by rubbing up 18o grs. of arrowroot or dextrine in a little cold water until a smooth paste results ; make this up to pint with boiling water. If the mixture does not at once become gelatinous it should be kept hot (not boiling) and stirred till it does. It should then be allowed to cool a little, and 16o grs. of ammonium chloride dissolved in about 4 oz. of water added to it. The mixture is applied while warm to the washed and ironed fabric, which is then dried and sensitised in the following bath : A. Citric acid . . 25 grs. 5o g.
Distilled water . oz. 50o ccs.
B. Silver nitrate . 6o grs. 125 g.
Distilled water . oz. 500 ccs.
Mix the two solutions. To sensitise the fabric use a Buckle or Blanchard brush. Pin the fabric to a flat board, pour upon it a little of the silver sensitising mixture rapidly and evenly, spread it over the entire surface, and dry in the dark. The fabric is printed upon as though it were P.O.P., toned with an acetate and gold toning bath, and fixed and washed like paper. It is desirable after washing and before toning to pass the print through a weak solution of sodium chloride (common salt), which gives reddish brown tones, or of sodium carbonate, which gives brownish purple tones. (See also " Diazotype," " Indigo Printing," etc.)