This is a permanent film that occurs in unusual circumstances and causes glassware to pit or erode.

In advanced stages, the glasses will appear frosted, spotted or cloudy.

To verify that the film is etching, soak the glass approximately 5 minutes in undiluted white vinegar. Rinse and dry.

If the film is not removed, it is etching.

Etching usually happens in soft water (0-3 grains), adjust the amount of detergent to match the hardness of the water.