Early Fox Talbot Photographs and Restoration by Neutron Irradiation

Abstract

In January 1839, W. H. F. Talbot of England displayed examples of his photographic-negative-and-paper-positive process. Talbot’s earliest image “permanentizers” were stabilizing or fixing solutions of either sodium chloride, potassium bromide or potassium iodide. These approaches proved unsuitable for longterm image stability. Even when he later adopted the use of hypo, his washing procedures did not necessarily ensure image permanency.

When it was observed that the image was fading on Talbot items in the Smithsonian collection, an investigation was undertaken to find a method of restoring them. Because Talbot modified his procedures constantly, it is almost impossible to restore the images chemically without first subjecting prints or negatives to chemical analysis. To avoid this problem a “non-destructive” method of image restoration was attempted Faded pictures were irradiated with neutrons, thus forming radioactive isotopes of some of the image An unexposed sheet of X-ray film was placed in contact with the sample for a short time and the yielding an autoradiographic copy containing a “restored” reproduction. This technique, is applicable only to examples which are relatively free of residual halides and non-ima