When soda lime glass is exposed to water, the water dissolves the sodium ions out of the
surface of the glass to form an alkaline sodium hydroxide. This in turn attacks the silica in
the glass, the added alkalinity of the dishwashing solution increases the probability of
etching. High water temperatures further lowers the resistance of soda lime glass etching.
How to retard Silica filming and Etching in Softened Hardened Water
Silica film and etching can be retarded and prevented by using the minimum amount of
dishwasher detergent, lower wash temperatures, ensuring wash water can reach all areas of
the DishDrawer® and using rinse aid. Rinse aid will help sheet off water rapidly.
Streaking and filming from high dissolved solids content of water can also be prevented by
using rinse aid.
Soft Water
Etching of glassware is the most common problem in naturally soft water. Etching is the
removal of metal ions form glass by an alkaline wash. Once the metals have been removed
they cannot be replaced. The first appearance of etching is fine scratches, this will
increase until there is an irregular film. The factors that contribute to etching in softened
water are the same for soft water.
Most naturally soft water have some calcium and magnesium, even though in small quantities
these still protect the metal ions in soda lime glass.
Coloured and Decorated Glass
Adding various metals to molten glass makes coloured glass. When the colour is an integral
part of the glass, it will not fade with automatic dishwashing.
Decorated glass is any glass that has colour applied to the outside after the glass object is
made. The decoration could be a metallic rim or a pattern on the outside. Decorations
cannot be fused onto the glass because the temperatures required would melt the glass
base. Therefore the decoration will get washed away with time. Overglazing of decoration
should always be washed by hand
S
S
T
T
A
A
I
I
N
N
L
L
E
E
S
S
S
S
S
S
T
T
E
E
E
E
L
L
About Stainless Steel
The main constituents of stainless steel are iron, carbon, chromium, manganese and in some
cases nickel. The iron, carbon and manganese are constituents of ordinary steel, but it is
the chromium and nickel that make steel “stainless”.
When cutlery is made it is shaped, ground, polished and last of all passivated. The
passivation process takes a small amount of chromium and nickel if present from the steel
and forms a thin film of chromium oxide and nickel oxide on the surface of the steel. It is
this film that makes the steel “stainless”. When the thin film is removed rusting occurs.
Acidic foods, salt and dairy foods will remove the oxide layer from stainless steel. Almost
any meal will contain some of these foods, so the stainless steel will be attacked. However
in the passivation process, the surface is preconditioned in such a way that if the stainless
is washed, rinsed and dried thoroughly and stored for a time, the oxygen will heal the
breaks in the oxide film layer and return the stainless property to the steel.
If the food is not promptly washed off the stainless steel, conditioning of the surface as
well as the oxide film may be removed. The air cannot heal the break and corrosion will take
place every time the stainless is wet.
