MACHINE DISHWASHING OF GLASS IN PRIVATE HOUSEHOLDS - RESEARCH RESULTSON GLASS DAMAGE

Against the background of the introduction of the new, low-alkaline co mpact dishwashing detergents and the associated glass damage during au tomatic dishwashing a comparative test was carried out. Glasses of dif ferent origin and composition were subjected to a continuous dishwashi ng test with up to 1000 cycles which compared the highly alkaline conv entional detergent with different new formulation variants of low-alka line compact detergents obtained from the market as well as with water . While the conventional and carbonate-containing compact detergent di d not cause visible corrosion, the detergent with a high disilicate co ntent already caused serious glass damage after 50 washing cycles in t he form of clouding and iridescence. These phenomena render the drinki ng glasses esthetically unsuitable. At the same time, on-glaze decorat ion of chinaware which is not resistant to machine dishwashing is prot ected by these last-mentioned detergents. Details of the processes in the washed glass surface were examined by means of XPS depth profiles up to a depth of 300 nm. It could be shown that during washing with au tomatic dishwashing detergents of a high disilicate content silica fro m the wash liquor separates in a similar structure as the glass itself on the glass surface, which causes the corrosion phenomena clouding a nd iridescence. Active substances and constituents of the wash liquor can be incorporated in the deposited layer. Since the new, low-alkalin e compact detergents are gaining more and more importance on the marke t, this paper was intended to clarify the causes of increasing glass c orrosion during machine dishwashing.