Toning was a chemical process which changed the colour of a photograph. It had a further benefit in that a toned image would be far more permanent. Gold toning came into use in the 1850s, using gold chloride.
The tone of the prints varied considerably, as the toning depended upon such factors as the density of the negative, the light, and even the way the paper had been sized. (For example, one finds that prints made in England seem warmer than those made in France, which was due to the fact that paper sizing in England was with gelatin).
© Robert Leggat, 1999.