Cleaning iron rust compounds from cotton textiles: application to Qing Dynasty armor

Abstract A composite structure consisting of cotton fabric and iron sheet was widely used in Qing Dynasty armor. Due to iron sheet corroding easily, the surfaces of cotton fabric were covered with numerous rust compounds, which has a significant negative impact on the relics. In this paper, by taking Qing Dynasty armor relics as the research object, the cleaning process was reported for cotton fabrics stained with corrosion products. Using an orthogonal experiment, rust stained model samples were used to explore a specialized and efficient cleaning process. Results show that the cleaning reagents, including ascorbic acid (mass fraction 10.0 g/L), ethylenediaminetetraacetic acid disodium salt (EDTA-2Na, mass fraction 10.0 g/L), and the surfactant composed of 70% rhamnolipid and 30% alkyl glycoside (mass fraction 8.0 g/L), could fully exert a synergistic effect. After treatment, the color difference (ΔE) value between the cleaned sample and the unstained sample is only 3.81. A series of comprehensive experimental results demonstrate that the cleaning procedure is effective and safe. There are almost no rust compounds and cleaning reagent residues, and no damage to cotton fiber. The reported wet cleaning process, aided by soft bristle brush, achieved good cleaning results, indicating that the process can be used to clean rust stain pollutants in Qing dynasty cotton armor.