3
3
M E T A L S
SILVER
Blackish-blue colouring
CAUSE
-Formation of silver sulphate. This is
produced when proteins break down.
Eg.: Egg, Mayonnaise, etc.
-Detergent inadequate or lacking silver
protection.
TREATMENT
-Wash the silver immediately.
-Use detergent with protection for
silver.
-Prevent contact between silver
utensils
- Use a recognised label detergent
FINE STEEL
Brownish-blue colouring
CAUSE
- Low quality steel
-Foods for example,
fruit, salads
- Check steel quality
- Increase programme
- Increase detergent dose.
TREATMENT
Rusting
CAUSE
- Low quality steels
- Oxidation in suspension (see
sheet 4)
TREATMENT
-Check the quality of the steel.
-Check if there is oxidation in
suspension by Sheet 4 procedure.
ALUMINIUM
Matt or coloration
CAUSE
Alloy
aO x i d o
TREATMENT
None
SILVER -- Silver is very appropriate for washing in dishwashers, for it is chemically stable. New detergents have protection forsilver.
FINE STEEL -- Cold steel is an ideal material for washing in dishwashers “IN THE CASE OF A HIGH –VALUE STEEL RUSTING DOES NOT OCCUR”. THERE ARE FINE STEELS DESIGNATED AS STAINLESS WHICH HOWEVER, CAN RUST-
ZINC – COPPER – BRASS -- Are not suitable for washing in a dishwasher
-
Wash with citric acid
-
“Vinegar or machine-
cleaner”
18.
