| About this Abstract |
| Meeting |
MS&T22: Materials Science & Technology
|
| Symposium
|
Art and Cultural Heritage: Discoveries during the Pandemic Year
|
| Presentation Title |
The Identification of Materials and Processes Used in the Manufacture of Orotone, Hand-Colored Orotone, and Silvertone Photographs |
| Author(s) |
Vanessa Johnson, Ivanny Jácome-Valladares, Claire Kenny, Tami Lasseter Clare |
| On-Site Speaker (Planned) |
Tami Lasseter Clare |
| Abstract Scope |
The orotone photographic process utilizes a positive image on a clear glass plate with a gold-colored metallic backing. This study analyzed seventeen orotones and silvertones to determine materials used in their production.
X-ray Fluorescence (XRF) spectroscopy identified copper and zinc in all metallic backings, while XRF and with Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy (SEM/EDS) identified aluminum in a silvertone backing. XRF spectroscopy identified silver bromide as the imaging material in all photographs. Glass for all orotones was determined to be soda-lime silica glass and sometimes contained arsenic or lead additives. XRF, Raman and Fourier Transform Infrared (FTIR) spectroscopies found vermilion, chromium yellow, cadmium yellow, and Prussian blue pigments in hand-colored orotones.
Analysis of a delaminating orotone using Pyrolysis/Gas Chromatography/Mass Spectrometry (Py/GC/MS) identified methacrylate polymers in the backing fluid. Ultraviolet-induced aging tests of amyl acetate, the most common backing fluid in orotones, ruled out these two acrylates as aging products. |