An investigation into the effectiveness of using a pH buffer in wet cleaning historical textiles

Abstract

A pH buffer is used in wet cleaning to control the pH of the wash solution. This research investigates the use and effectiveness of pH buffers for wet cleaning in textile conservation through questionnaires sent to practising textile conservators and by conducting wet cleaning experiments. The most commonly used pH buffers were found to be tri-ammonium citrate and tri-sodium citrate self buffers. Experiments were conducted on naturally aged cotton and silk fabrics using Hostapon T® and Dehypon LS45® respectively, with tri-sodium citrate self buffer and tri-sodium citrate with citric acid and sodium hydroxide with citric acid combination buffers at comparable concentrations. The experiments focused on measurement of the pH of the wash baths, the change in pH of the samples and, to quantify soiling removal, the colour change of the samples. Citric acid in the pH buffer reduced the cloud point of Dehypon LS45®. Tri-sodium citrate was most effective at increasing soiling removal. Tri-sodium citrate in combination with citric acid was found to buffer the pH of the wash solutions most effectively and was also effective at increasing soiling removal.