If your glasses came out of the dishwasher cloudy or looking scratched, you need to determine what type of damage the machine caused. If your glasses truly have scratches, you probably cannot fix them, but you may be able to reverse cloudiness caused by other problems. Learning how to prevent the problem in the future will keep your glassware crystal clear.
Sometimes, a white film you perceive as scratches on your glasses actually comes from hard-water deposits settling on them in the dishwasher. The damage happens slowly, over time, with repeated dishwasher cycles and also likely appears on your silverware. Suspect this film as the culprit if you live in an area with hard water, especially if the water inside the machine does not reach at least 140 degrees Fahrenheit.
A more serious problem of etching also can result in a cloudy film on your glassware. This permanent, white coating comes when the glass itself becomes scratched or pitted. Early on, glasses may show a rainbow effect when viewed at certain angles in the light, but, in time, the etching takes on an overall white or frosty appearance. In certain regions, softened water interacts with phosphates in certain detergents to cause the etching.
Try removing the hard-water film by soaking the glasses in white vinegar for 15 minutes. Alternately, wash the glassware with water and a good amount of dishwasher detergent but protect your hands from the corrosive detergent by wearing rubber gloves, University of Nebraska Cooperative Extension homemaking experts recommend. You likely cannot remove scratches or etching, however, and the glasses will remain cloudy if that caused the film.
To prevent hard-water film, avoid leaving heavy remnants of food on your dishes, which may settle back on glasses and contribute to the problem. Use a food thermometer to ensure the water reaches at least 140 degrees Fahrenheit to properly dissolve the detergent and use a rinse agent in the dishwasher. Keep your glasses from etching by lowering the amount of detergent you use if you have softened water and take the glasses out of the machine before the heat-dry cycle starts. Detergent with low or no phosphates also helps prevent scratching and pitting.