What Causes the Spots on Silverware in a Dishwasher?

Food Residue

• Don't put dirty dishes and silverware into the dishwasher and let them sit for a day or two before initiating the cycle. If the silverware has food residue on it from acidic foods like citrus sauces or juices, tomato sauce or vinegar-based salad dressings, the deposits may leave dark marks on the metal. Certain types of oil also mar the finish on silverware.

Crowding

• If you vary the types of silverware pieces in the dishwasher holder, it keeps forks and spoons from nesting together and preventing the surfaces from being fully exposed to the soap and water of the machine. Although grouping like utensils together is handier when unloading the dishwasher, spots will form on improperly exposed surfaces.

Dishwasher Detergent Ingredients

• Many dishwasher detergents have natural or artificial citrus ingredients added to them to mask the soap smells. Lemon, orange and grapefruit additives have the same effects as leaving similar food residue on the silverware and cause dark spotting.

Water Composition

• Depending on the source of your water, it is classified as either soft or hard. Soft water has fewer chemicals and easily forms lots of bubbles with detergents. Softer water bubbles are more difficult to rinse away and often leave filmy spots on silverware. Hard water not only requires more detergent, but it also causes metal to discolor over time.

Easy Solutions

• If you let silverware soak in clear water and place it into the dishwasher right before you turn it on, residue is less likely to cause spots. Mixing knives, forks and spoons in the silverware basket promotes less spotting. Dishwasher detergents with minimal scents added tend to reduce the spots on silverware. Adding water softeners to hard water and balancing solutions to soft water often reduces spots on dishes and silverware.

Maintenance

• In addition to changing your dishwasher cleaning habits, treat your silverware to a thorough hand cleaning every few months. Clean each piece with a vinegar and water solution to remove streaks and spots, and polish it to a high sheen with a soft cotton cloth, which will make the metal less likely to develop spots during subsequent dishwasher cleaning.