The basis of the photographic process based on the conversion of light-sensitive substances, halides of silver, often bromide. While in the light-sensitive emulsion, they break down under the action of light and dark areas appear tiny crystalline grains of silver.
While silver is a precious metal, it is necessary not only for pictures. So researchers are looking for such light-sensitive substances and systems, which would not contain silver. On this path there are good finds, but effective substitute has not been found yet. However, for some purposes the picture without silver or almost without money successfully used. And such an unusual processes can be replicated independently. Here are a few examples.
In 100 ml of distilled water dissolve 15g of glucose and 2 g of ammonium bichromate. Pure fine white cloth, saturate the prepared solution and dry it, but always in the dark, because it was light and in the dark as iron iron. In advance, prepare a developing solution. It consists of 1 g of silver nitrate (to manage at all without silver salts cannot) and 10 ml of acetic acid per 100 ml of water.
Make a Ghost image of the image - the image that you would like to transfer onto the fabric. Put the tracing paper on top of the fabric and bring to the light of day. Do not rush; to photochemical process is completed, it will take about five minutes, and when the electric light, and even more. For the manifestations of the lower fabric in the developing solution. Total darkness is already optional, valid weak diffused light.
Dry manifested fabric; her dark brown pattern.
In this experiment you used the recovery properties of glucose - it restores chrome in ammonium bichromate. And the bichromate, which has not recovered, entered into reaction with silver ions from the developer, formed a colored compound, which remained on the fabric, as it is insoluble. And because the color appeared on the dark areas, you've got a positive image.
Another variant of this method, too, with the bichromate of ammonium, but without glucose and, more importantly, without money even in the developer. Prepare the emulsion, consisting of two solutions. First a solution of 17 grams of wood glue and 6 g of gelatin, pour 100 ml of water, add 3 ml of an aqueous solution of ammonia and leave to swell for a day, and then heat for about an hour on a water bath at 80°C until complete dissolution. Second solution: 2.5 g of ammonium bichromate and homoclinic alum, 3 ml of an aqueous ammonia solution, 30 ml of water and 6 ml of alcohol. When the first solution to cool to approximately 50°C, With vigorous stirring, pour into it the second solution and the resulting emulsion double-strain (better - through cotton wool). Put it in a dark place, and the following operation is the application of the emulsion on metal, glass or ceramic plate - spend in a darkened room.
Warmed up to 30 - 40°C emulsion pour in a thin stream onto a clean plate, bokacheva her to flatten the layer. 10-15 minutes will possithe plate, preferably by heating, and, as in the previous experience, put on the light-sensitive layer of tracing paper with the image. Push the glass, so she straightened up, and light. A few minutes in the sun is what you need, and if the lighting is artificial, then turn on for 10 minutes a few lamps with a total power of about 2000 W, preferably with reflectors.
To show it immediately, otherwise chromic salts Sabbath gelatine and, where not necessary. The developer is a little warm, not more than 30°C, water. Nezabvenna gelatin will dissolve. And those areas in which under the action of light proteins gelatin hardened, will remain on the surface.
The image was not very clear. To rectify this, immerse the print in 1%solution of the indicator methyl violet (you can take diluted purple ink). Rinse the plate with water and start fixing solution: 5 g of ammonium bichromate, 2 g homoclinic alum and 4 ml of alcohol per 100 ml of water; the time is 3-4 minutes. Dry the photo on the air. For additional securing of the picture you can heat it for a few minutes in a drying Cabinet or in the oven.
The following Bessarabian picture will make it more habitually on paper. However, the filter; but still this experience demonstration.
Circle paper immerse in a solution containing 20 ml of 5%solutions of red blood salt To3[Fe(CP)6], ferric chloride, FeCl3 and oxalic acid NEOZOON (carefully!). Impregnated paper remove from the solution and dry in the dark, then place the tracing paper with a picture and will savetime sunlight. Incandescent lamps for this purpose are not suitable, but UV (quartz) lamp will do. Lit places will be a dark blue because of the formation of the familiar turbulency blue. Manifestation is not necessary, and for fixing wash the paper with water to remove substances that have not entered into reaction.
And last experience with Bessarabians photography. In one beaker dissolve in 100 ml of water, 0.4 g of iron chloride ( III ) and oxalic acid, another 1.4 g of copper chloride in the same amount of water. Mix 10 ml of the first and 0.6 ml of the second solution, soak a mixture of filter paper and dry it in the dark. Prepare developer: 3.5 g of copper sulphate, 17 g of Rochelle salt (double sodium-potassium salt of tartaric acid), 5 g of caustic soda (be careful!) 100 ml of water and mix with 25 ml of 40%solution of formaldehyde. Again Servette paper in sunlight or under an ultraviolet lamp through the tracing paper with a pattern; in contrast to the previous experience of the first image is not visible. It will appear after 15 minutes of exposure to the developer and rinse in plenty of water.
This process is somewhat similar to silver photograph because the light-sensitive layer are also formed centers of crystallization, but not silver, and copper; however, copper is not deposited from the emulsion, as in conventional photography, and of the developing solution.