Dishwashing Film on Glass or Crystal
Glassware washed in an automatic dishwasher
occasionally develops a cloudy film, which may be one of
two different problems.
Hard water film is caused by very hard water or not
enough detergent to soften the water. A failure of a home
or municipal water softening system may temporarily make
the water too hard. If vinegar applied to the film spot
for a minute or so removes it, this is a hard water film.
You can reduce this problem by using the maximum
recommended amount of detergent, or stop it by installing
a water softener. Also check to be sure the detergent cup
fits tight and works all right so detergent is released
at proper time in wash cycles.
Silica film is caused by high phosphate detergents
in very hot (above 140 F.) water that has been softened.
Insufficient rinsing also increases this, since detergent
is not removed. This begins as a colored film (like oil
in water) which can be removed by scratching with a pin.
Later on it become cloudy and cannot be removed by
scratching. You cannot remove it with vinegar or other
acids; it is permanent. The glass is permanently etched.
Some glass is more resistant to this than others. You
can slow the buildup by using no more detergent than
needed for soil removal, using water no hotter than 140
F., and loading so all detergent is rinsed off.