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updated August 1, 2002


Hard Water Filming
submitted by Lorene Bartos, Extension Educator

Do you find a film or cloudiness on your glasses after they have been in the dishwasher? This usually happens after several washings. Hard water filming is the white film that appears on glasses and flatware. Etching is a permanent film that occurs in unusual circumstances when the surface of the glass is pitted or eroded. In the beginning stages, etching may be identified by an iridescent look - shades of blue, purple, brown or pink may be seen when the glass is held at an angle in the light. In advanced stages, the surface of the glassware appears frosted or cloudy.

Possible causes of filming may be:

(1) Hard water and not enough detergent. This combination may leave hard water minerals that dry on the surface of the glassware creating a film. Unremoved food soil may also cause filming.

(2) Low water temperature. The water temperature should be 140 degrees F. as it enters the dishwasher. Check the water temperature by placing a candy or meat thermometer in a glass and letting it fill with water from the hot water faucet in the kitchen sink. Let the water run until the temperature stops rising. If it is not 140 degrees F., adjust the water heater. If the dishwasher is not near the hot water heater, let the water run before starting the dishwasher this clears the line of cold water.

(3) Not using a rinse additive. A rinse additive such as JET-DRY improves the sheeting action of the water. Use liquid rinse additive in the rinse dispenser. If the dishwasher is not equipped with a dispenser, hang a basket of solid rinse additive in a back corner of the lower rack.

To remove filming, soak glasses approximately 15 minutes in undiluted white vinegar. Rinse and dry. Or, wash the glasses in a basin of water using a generous amount of dishwasher detergent (wear rubber gloves to protect your hands from the strong detergent solution).

Etching may happen to certain types of glassware in any dishwasher with the combination of soft water (especially mechanically softened), an excessive amount of detergent, heat and prerinsing. There is no way to remove the filmy appearance caused by etching - the damage is permanent. Neither is there any way to predict what glassware may be affected in this way as there is no relationship to the cost or quality of the glass.

To prevent etching:

1. Adjust the amount of detergent according to water hardness. See chart below.

2. Lower the water temperature so it enters the dishwasher at approximately 140 degrees F. Do not use a water heating option such as Temp Boost, Power Boost or Power Scrub.

3. Use the no heat Energy Saver dry cycle, if you have one.

4. Do not manually prerinse dishes before loading in dishwasher. Prerinsing prior to loading to remove all food soil increases the alkaline concentration of the dishwasher detergent.

This chart shows the amount of detergent to use for each wash according to water hardness (measured in grains per gallon). Lincoln's water is 11.1 grains per gallon. One tablespoon of detergent per wash is the minimum amount recommended.

0-3 Grains Hardness 1 Tablespoon (fill dispenser cup ¼ full)
4-6 Grains Hardness 2 Tablespoons (fill dispenser cup ½ full)
7-9 Grains Hardness 3 Tablespoons (fill dispenser cup ¾ full)
10-12 Grains Hardness 4 Tablespoons (fill dispenser cup completely full)

When water is over 12 grains hard, it will be necessary to use the Low Energy wash cycle and fill both cups completely full of detergent. If you have soft water, that is used in the dishwasher, adjust detergent accordingly.


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