Studies on the Authorship of Albumen Vintage Photographs: A Combined Experimental and Chemometric Approach

TL;DR

This paper uses chemical analysis and statistical methods to determine the authorship and age of old albumen photographs.

Contribution

The study introduces a chemometric approach combining PCA and spectroscopy to identify the origin and production time of vintage photographs.

Findings

PCA analysis successfully distinguished photographs based on authorship and production time.

Empirical relationships were established between silver particle content and photo development conditions.

Reference samples validated the chemometric method's accuracy in identifying photographic origins.

Abstract

The differences in albumen photographs from vintage photographic studios were identified by energy-dispersive X-ray fluorescence spectroscopy and Fourier transform infrared spectroscopy. The results inspired the concept of finding common features characteristic of a given photographic studio. The obtained measurement data (i.e., positions of vibrational bands for characteristic groups of albumen and the mass contents of chosen elements) were analyzed chemometrically by employing the Principal Component Analysis (PCA). The PCA technique allowed us to reduce the number of relevant experimental parameters characterizing the unique features of the photographic objects. The two major components were able to distinguish the photographic objects in terms of their authorship and the time to produce a photograph. The method developed was examined for a selected group of photographs consisting of albumen prints from three Polish photographic ateliers. To validate ED-XRF measurements and, consequently, the chemometric findings, reference albumen photo samples were designed and prepared. The empirical functional relationships between the content of photochemically reduced silver particles on the photographic paper and several physicochemical factors, including time of exposure to UV light, AgNO3 concentration in a fixed bath, and concentrations of other additives, were proposed. These results can be used for the prediction of the experimental conditions under which the investigated photographs were developed.

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