High-frequency plasma in heritage photo decontamination

Abstract

This paper attempts to prove that high frequency (HF) plasma decontamination of photos is an efficient method. The color and gloss measurement, SEM and microbiological analysis were used to evidence the differences which appear after plasma treatment. The HF cold air plasma experiments were carried out under the following working conditions: temperature 35–40°C, pressure 3.5×10−1–7×10−1 mbar, frequency 13.5 MHz, over a period of 20 or 30 min. Microbiological analysis has proved the presence of the bacteria (genera: Bacillus, Sarcina, Micrococcus, Clostridium) and fungi (genera: Alternaria, Cladosporium, Aspergillus, Penicillium, Rhizopus). After the treatment, the total fungic decontamination point to the effect of HF plasma on genera Aspergillus, Cladosporium, Alternaria, Penicillium and Rhizopus. In bacterial decontamination, the inhibition of growth and strain development in the genera Sarcina and Micrococcus is noticeable after a plasma treatment of 20 and 30 min. The growth and strain development of Clostridium and Bacillus were inhibited only after 30 min treatment. The difference of color after the treatment indicates the cleaning effects of plasma.