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Treatment; 18 May 2018; Clean surface; Organics

Reason: Temporary Exhibition
Description: Attempts to clean the plate using xylene and white spirit were unsuccesful. After measuring the pH of the plate (believed to be approx 4-4.5 based on pH of water droplet left on the plate for 30 mins tested using basic pH indicator strip) the plate was water cleaned using de-ionised water to which acetic acid was added to provide a pH of 4-4.5. Cleaning was undertaken using soft cotton cloth, kimtech wipes and swaps covered with silk. This enabled the removal of surface soiling with minimal removal of lacquer. This was particularly successful on the front of the plate. Cleaning stopped when more lacquer than soiling was noted on cleaning cloths. It was noted that on the reverse of the plate, soiling or degredation was more severe and more orange/ mustard material was removed to achieve a semi-cleaned appearance than is ideal. It is unclear whether cleaning was removing lacquer, or if perhaps there was a surface coating. Examination under micropcope was unhlepful. The decison to clean the reverse even though laquer was suspected to be being removed slightly was due to the extreme differences between the visual appearance of the front (glossy) and back (very matte). A balanced clean on the reverse which reduced the matte look but was not high gloss was aimed for.
Details: Treatment