Student Research Projects

Determination of concentration of leached Cadmium in various stain glazes

Student Lilly Moon, '16
Faculty Mentor(s)
Department Chemistry
Course Chemistry 480: Instrumental Methods of Analysis


The use of cadmium in glazing process is frequent due to its brilliant colors of orange, yellow, and red colors when it is combined with Selenium and other elements. However, the presence of heavy metals such as cadmium can result in adverse effects on animal and human health, if transmitted though the food chain. Thus, the use of glazes containing cadmium to decorate dinnerware can constitute health hazards, and FDA regulates the limit of exposure to cadmium to the range of 0.25ug/mL~0.5ug/mL. Encapsulated cadmium stains are supposed to encapsulate the cadmium in Zincron-silicate so that there wouldn’t be any exposure of cadmium to the food/water, but many users are worried that the glaze stain will still poison the food/water in the ceramic vessel. The encapsulated zincron-silicate cadmium-sulfoselenide stains aren’t used frequently by the potters even though they give off the vibrant colors because of the toxic nature in the cadmium. Thus, the goal of this research project is to determine the concentration of cadmium that may be leached into food or water. A modified FDA leaching method involving five hour leaching with 4% acetic acid at 60 ̊C was used, and the concentration of cadmium was determined using FAA. Although preliminary results showed significant levels of leachable cadmium in the powder form, it’s expected that after the firing process, the encapsulated cadmium glaze will result in food-safe levels of cadmium, which is lower than the 0.5ug/mL, the maximum amount of cadmium set by FDA. The results of the analysis of the fired glazes will be discussed.