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|CHRIS SHEPHEARD||Telephone: 01252 710664||Email:|
Most people regard sepia tinted photographs as being synonymous with a bygone age, and it is certainly true that this is a craft little practised by the present generation of photographers.
A common misconception is that this toning was done purely for aesthetic appeal. In fact it was largely for practical reasons. In the early days of photography most photographers produced their own materials in far from ideal conditions, and as a result impurities and imperfections in the process were very common.
Black and white photographic images are composed of silver compounds which are inherently unstable unless all the developing and fixing chemicals are totally removed from the paper. If impurities exist, in time these silver compounds will either fade or break down to form metallic silver once again.
The simplest way to prevent this from happening was to replace the silver compounds with those of a more stable nature. The simplest to use was sulphur, but this changed the image colour from black to dark brown, the sepia we know today.
For the technically minded, a normal black and white print is produced which is fixed and washed thoroughly. This is then bleached in a solution of potassium bromide and potassium ferricyanide. After a very thorough wash this is toned in a solution of sodium sulphide, then washed and dried in the normal way.
To see an example of sepia toning please visit the "Oldpics" collection page.