IDENTIFICATION OF A TONING TECHNIQUE.

It is frequently difficult to be certain what method was used to tone a print unless some means of analysing the image material is used. Small particles can be removed and in some cases of metallic toning, conventional inorganic qualitative analysis can be used to identify the metal. In other cases, only spectral absorption can be used and yet, there has been very little research done to enable comparative studies to be used for identification. No doubt eventually there will exist a relatively simply and cheap method. In the meantime if we really need to know it is possible using mass spectroscopy.