Patent ID: 8021493

Claim:
A method of reducing corrosion of an article during cleaning, the method comprising: (a) diluting a warewashing composition with water at a dilution ratio of water to warewashing composition of at least about 20:1 to form a use composition, wherein the warewashing composition comprises: (i) a cleaning agent comprising a detersive amount of a surfactant; (ii) an alkaline source in an amount effective to provide a use composition having a pH of at least about 8 when measured at a solids concentration of about 0.5 wt%; and (iii) about 1 wt% to about 5 wt% of an unencapsulated corrosion inhibitor consisting of a mixture of a calcium salt and a magnesium salt, wherein the salt has a water solubility of less than about 0.5 wt% in water at about 20° C. and atmospheric pressure; and the corrosion inhibitor reduces the corrosion of glass; and wherein the warewashing composition does not contain phosphorus-containing compounds; and (b) contacting the article with the use composition in an automatic dishwashing machine, wherein the salt precipitates to form a protective layer on the article in contact with the use composition.