Appendix P Chemically treating black and white prints

Even after you have made a black and white bromide print, there are still several ways you can alter the image by chemical means. You can decide to make your picture lighter in tone or bleach away parts to white paper, or tone it so that the neutral black image turns into a color. All these chemical treatments are carried out in trays, working under ordinary room lighting.

Start off with a fully fixed and washed print. If it has already dried re-soak it in water for 2–3 minutes, then blot it or wipe off surplus liquid. Working on a damp print helps the chemicals to act evenly.

Reducing (lightening) the image

Farmer’s reducer is a mixture of potassium ferricyanide and hypo. This forms a yellow solution which you apply on a cotton wool swab to over-dark parts of the picture. Then immediately hold your print under a cold water tap to halt the reduction. Examine the effect carefully. Repeat the process – just a little at a time – until the part of the print (or the entire image) is sufficiently lightened. If you go too far there is no way you can bring back the image again. Finally re-fix and wash the whole print.

Farmer’s reducer has its most rapid effect on the palest tones in an image, so it is excellent for the overall ‘brightening up’ of pictures with veiled-over (gray) highlights. Don’t expect to rescue a really dark print this way, however – if overdone the reducer leaves a yellowish stain and brownish-black tones. Farmer’s reducer can also be used to lighten very dense, low-contrast negatives; i.e. overexposed and underdeveloped. At the same time it greatly exaggerates the graininess of the image.

Bleaching to white with iodine

By using an iodine bleacher you can erase chosen parts of your print right down to white paper, without leaving any final stain. It is ideal for removing an unwanted background to a subject, leaving it with a ‘cut-out’ appearance. Two separate solutions are needed – the bleacher itself and a tray of print-strength fixer.

As Figure P.1 shows, paint over the unwanted area of your print with a swab of cotton wool (changing to a watercolor brush when working close to the edges of fine detail). A strong brown stain immediately appears, with the black image fast vanishing beneath it. Wait until the unwanted parts have lost all their black silver, then rinse the whole print in water for at least 30 seconds. Next put it in the fixer solution for 5 minutes or so until the brown stain has completely disappeared, leaving clean white paper. Finally, wash the print for the same time recommended for your printing paper after regular fixing.

Figure P.1 Erasing the background from a print with iodine bleach.

Sepia toning

Changing the print image from black into sepia is the simplest and most popular toning process. It gives a rich sepia or chocolate color, like a nineteenth-century photograph. Sepia toning is also advisable before hand coloring.

You need two separate solutions, bleacher and toner. Slide the print into the tray of bleacher, face up, and rock it for a minute or so until the once black image is bleached to a pale straw color. You then rinse it under the cold water tap and place it in a tray of toner solution. The picture reappears in a sepia color within a few seconds, but needs 2–3 minutes to reach full richness and depth. You finish off by washing and drying in exactly the same way as when making the print in the first instance.

The image now consists of brownish silver sulfide instead of the usual black metallic silver. This is very permanent – you cannot return a sepia print to black. Remember too that with toners of this kind bleaching is essential before the black image can become sepia. You can therefore selectively bleach, say, just the background to your main subject by carefully applying bleacher on a brush or swab. Only this area then becomes sepia in the toner, leaving the main image untoned.

Another alternative is to dilute the bleacher with an equal volume of water to slow its action. You then immerse the whole print but remove it before darkest grays and shadows have lost their black appearance. After completing the toning stage of the process as normal your picture consists of a mixture of sepia and black. Results have deeper brown-black shadows than given by full toning. And if you don’t like the result just re-bleach your print to affect the remaining black parts and tone the print again to get a fully sepia image.

Figure P.2 Routine for sepia toning prints

You can also buy kits of multi-toner chemicals, typically consisting of a bleacher and a range of toners, each of which will result in a different color image. A kit with yellow, magenta and blue toners permits you to mix them in varying proportions (blue and yellow to get green, for example) and so form a wide choice of image hues. Most results are rather garish; some are not very permanent and alter with time.

Multi-brown toner

Moving beyond simple sepia toner it is possible to alter the distinct shade of brown using a two-part brown toner based on thiocarbamide. Sepia provides a constant color change to all your prints. You have no choice about the shade of brown that your images become. In contrast the two-part thiocarbamide toner detailed here will give you a color choice in the toning process. By adjusting the ratio of parts A and B of the toner, you can produce a range of browns from purple brown, through a neutral brown, to yellow brown. In this way you can control the color of the final print.

To start coloring your prints, you must first carefully make up the bleach and toning solutions. Ensure that the print to be toned is fully fixed and carefully washed. Bleach the photograph by gently agitating the picture in a tray of the bleaching solution. Wash the image until all yellow staining is removed. Mix toner parts A and B to the ratio needed for the color you require. Immerse the print into the tray of toner and agitate until all toning stops. Wash the photograph again and dry as normal.

It may be helpful to make up a toning palette to assist you with deciding what tone your next print will be. Smaller changes in color can be achieved by adjusting the ratios of the toner parts. Keep in mind when you are experimenting that not all photographic papers are manufactured in the same way using the same emulsions. Such differences will change the way in which the toner reacts with the image. For example, a chlorobromide-based paper will always give you a warmer toned image than a straight bromide paper (see formula below).

Chemicals required

Farmer’s reducer and most toners can be bought as packs of ready-weighed powders and liquids from manufacturers such as Tetenal. This is the most convenient and, in the long run, cheapest way of working. To make up your own solutions, however, prepare them from the following chemicals.