Studies of lead corrosion in acetic acid environments

Abstract

Many lead artifacts are danzaged after being kept for a short period in enclosures that contain materials which emit carboxylic acids. The formation of corrosion products and the corrosion sensitivity of lead were studied under experimental conditions in which the duration of exposure, the acetic acid (ethanoic acid) concentration and the relative humidity (RH) were varied. At 54% RH, in the acetic acid concentration range studied, weight gain was maximun at around 4mgm−3. Over a period of 12 months, with RH levels below 75%, no damage was detected on lead samples at acetic acid concentrations below 0·43mgm−3. However, variations in the composition and morphology of lead as well as the presence of other carbonyl compounds in enclosures may affect the rate of corrosion. For these reasons, a total concentration of low molecular weight carbonyl compounds no higher than 0·1mgm−3 is recommended. Strategies to maintain the concentration of carbonyl compounds below 0·1mgm−3 are proposed.