An investigation into the use of the chelating agent tri-sodium citrate in Loponite and methylcellulose gel formulations for the removal of metallic staining

Abstract

This study investigates whether Loponite and methylcellulose gels can be effective carriers for the chelating agent tri-sodium citrate with the purpose of removing metallic staining from textiles. Whereas chelating agents are often used in immersion treatments, this is not always a suitable option for some textile substrates, so localised treatments provide an alternative solution. The gel/tri-sodium citrate formulations were tested on undyed cotton and silk samples to determine the most effective gel/chelating agent concentrations, investigate their working properties, how effectively they rinse from fabric, and whether any residues remain. Following this, the chelation abilities of the gel/tri-sodium citrate formulations were tested on alum-mordanted dyed silk samples, where the aim was to draw the dye from the fabric into the gel through the tri-sodium citrate chelating with the aluminium in the mordant. Methods to deposit metallic soiling onto fabric, in this instance copper corrosion, were also examined. The results were mixed: the gels were easy to combine and apply to the fabric but left residues. Chelation was ineffective, and a negligible amount of dye was removed from the test samples. The dissertation concludes with a comparison of the two gels, with the aim of providing guidance for textile conservators exploring this method of treatment.