Post #36034 by Saint-Thomas on Mon, May 26, 2003 10:01 PM

Dishwasher detergent contains alkalais which will chemically react to some of the components of the glaze, namely the ones which color it, if the glaze is not formulated properly. Many factors which you have no way of determining include, is there enough silica?, was it fired to the proper temperature (matured), is the glaze overloaded with metal( copper, iron, etc.)

It is sad that most commercial ceramics producers rarely pay attention to these things. I would treat all ceramics as dishwasher safe, unless it holds some value to you. You never know how durable the glaze is. Also keep citrus away from your mugs. Lemon will turn a nice green mug into a lemon wedge- shaped, colorless spot if the manufacturer didn't formulate or fire the glaze properly.
My mugs are dishwasher safe. (except the gold ones!)