+ My product has stains of rust. Why?
If rust spots are visible on a lunch box, many people believe that inferior metal has been used and that it must therefore be a complaint. There is a widespread misconception that stainless steel cannot rust. Stainless steel consists of approx. 70 % iron. The rust resistance is only created by a protective layer (also known as a passive layer). This protective layer consists mainly of chromium and other precious metals such as nickel. Corrosion (rust) can have various causes, such as incorrect use of the stainless steel product or excessive exposure to chloride. Even briefly exceeding the limit values is enough to damage the passive layer.
https://ecobrotbox.de/en/frequently-asked-questions/care-cleaning/my-product-has-stains-of-rust.-why
Causes of corrosion (rust):
- There are rust particles in the air (flash rust) which are deposited on the surface. However, rust film can also be transferred by other sources of rust (e.g. in the dishwasher). These can be, for example, non-rusting screws of pots or dishwasher baskets whose plastic coating has been damaged.
- The water has a high iron content, the particles react with the chlorine and deposit on the stainless steel.
- The chlorine content of the water is or was too high.
- The water contains a high salt content and is operated at high temperatures.
Translated with DeepL.com (free version)
All stainless steel parts should be cleaned regularly. Commercially available household cleaners that are suitable for stainless steel (i.e. without acetic or citric acid) can be used safely in conjunction with a soft cloth or sponge. Cleaning sponges made of steel wool and cleaners containing vinegar, citric or hydrochloric acid are unsuitable for cleaning stainless steel. To ensure that your stainless steel product continues to shine for a long time and no unsightly rust spots form, you should take the precautions mentioned above.