Does anything but metal grate

Prevent flash rust in the dishwasher

I love my dishwasher. What annoys me is the rust film: brown stains on the knives of good cutlery. Sometimes more sometimes less. But there has not been a wash cycle without it for a long time. The rust stains can no longer be completely removed.

What helps to prevent rust film? There are just three basic rules you need to follow. Wash the old potato knife by hand. Put the aluminum foil in the cutlery tray. And keep the cutlery clean and dry. We explain why.

What is rust film?

Flash rust actually consists of small rust particles. It occurs when unalloyed, i.e. unrefined, iron comes into contact with oxygen and water. Individual iron particles are then removed and washed through the machine as rust with the water. Strictly speaking, the rust film does not fly, it flows or swims.

If you now discover brown stains on cutlery, kitchen utensils and stainless steel pots for the first time, then these are not the sources of the rust. He just dropped off there. You have to look for the source of the rust somewhere else.

Why is stainless steel dishwasher safe?

Stainless steel cutlery can be described as dishwasher-safe if it can withstand more than a thousand washes without being damaged. The surface is usually covered with a coating of chromium oxide. This can even repair itself.

You can recognize high-quality stainless steel by the marking 18/10 or 18/8. The two digits stand for admixtures that ultimately make the stainless steel suitable for the dishwasher: 18 percent chromium and 10 and 8 percent nickel, respectively.

But watch out: you shouldn't blindly trust what the manufacturers say. Stiftung Warentest has found that dishwasher resistance often disappears after a few hundred washes.

What is pitting?

If, over time, the rust stains can no longer be completely removed and small black dots remain, then pitting has started, also known as pitting corrosion.

Small holes then formed in the protective layer of the stainless steel that were initially invisible. This allows salts to penetrate inwards and promote pitting corrosion.

Knife edges are often affected because their protective layer is quite thin. In addition, leftovers containing these salts often stick to them for a long time.

Where does the rust film come from?

Back to top. The rust film must originally come from somewhere. These are all metal objects that do not belong in the dishwasher. Namely when they don't completely are made of stainless steel.

These are, for example, sieves made of a wire mesh, the wire ends of which are not sealed. But also baking molds. Old potato peeler. Or kitchen knives whose rivets in the handle are not made of stainless steel. The screws and rivets of some pots and pans are not rust-proof either.

In other words: cheap goods. Decrepit or damaged objects are also a common reason for flash rust. Even dishwashers can cause rust film. Some crockery or cutlery baskets are made of metal that has only been coated with a layer of lacquer.

If you drop your sharp kitchen knives with the point always down into the cutlery basket, it can be damaged in the long run and be a source of rust film. This can be remedied by some silicone or electrical tape - at least for a while. In the advanced state of the surface rust opencast mining, you should completely replace the basket.

How can you avoid flash rust?

There are two approaches you can take to avoid rust film in your dishwasher. You can prevent it from arising. That will not be entirely successful. Then you can still try to keep the rust away from your good cutlery. There are two approaches to this as well. Only the combination is really effective.

Hand washes whatever rust creates

Old peelers, kitchen knives and metal sieves do not belong in the dishwasher if they are not made entirely of stainless steel or if their surface has been damaged. This also includes pitting-infected knives from good cutlery. Always wash these parts by hand.

It is not that easy to find out from which parts the rust film originates. Even if I thought I had only put dishwasher-safe parts in the machine, I often had enough rust film on the knife edge afterwards.

Then all you have to do is pay attention and try out. Keep more and more parts out of the dishwasher until you are sure where the rust film is coming from.

You can of course also replace the culprits. However, my heart is attached to one or the other knife that still comes from the family. I rarely use it now - or just wash it by hand. However, when buying a new one, I pay attention to the suitability for the dishwasher and sometimes do without it in favor of practicality in everyday life.

Put aluminum foil in the cutlery basket

Aluminum is a magnet for rust film and attracts it. It will then not end up on your knives (or at least significantly less).

Aluminum is a so-called sacrificial anode. It oxidizes more easily than your cutlery and pots and therefore accepts rust more easily - if not completely.

The easiest way to put aluminum in the dishwasher is to put a crumpled piece of aluminum foil in the cutlery basket or on the cutlery compartment. Ultimately, however, it doesn't matter where it is in the dishwasher.

However, the aluminum foil will lose its effect as a rust magnet over time. You therefore have to change them regularly. Alternatively, you can also use a more massive piece of aluminum - for example an aluminum plate for silver cleaning or a piece from the hardware store.

Since this is how aluminum gets into the environment and pollutes the environment, you should first try to eliminate the causes of flash rust and only use the aluminum if there is no other option.

Take care of your knives - before and after washing the dishes

Removes rust film from knives that come out of the dishwasher. And rinse them immediately after use before putting them in the dishwasher. This prevents pitting in the long term.

We explain below how to remove rust film. However, it is even more important not to leave the knives lying around for long after use. Rinse it once under running water to remove acidic foods that can cause pitting.

Clean cutlery should not stay moist in the machine for long. When the program ends, open the door immediately and let the steam escape. Or choose a program that effectively dries the contents. Take this into account when buying a dishwasher. It is best, however, to dry your stainless steel, which is at risk, immediately with a soft cloth.

Take care of your dishwasher

Don't use too much salt and clean your dishwasher. Replaces metal inserts whose plastic coating is damaged.

Put your sharp and pointed kitchen knives on a shelf made of pure plastic. In my dishwasher, this is located in the top left above the glasses. This shelf is even intended for this. The knives are not lying, but are set up in a holder.

Regularly clean your machine. Removes residues that still contain dishwasher salt. These tend to form a white veil on the bottom of the machine. It is best to try to find the right amount of salt, which you put in the designated compartment or on the tab.

Remove rust film

You should remove rust film quickly to prevent pitting corrosion. So don't be satisfied with the fact that the stain has actually always been there and the knife actually comes out of the dishwasher clean. Do something about it.

There are various special cleaners in the drugstore. You can use a stainless steel cleaner that contains polishing clay. Or whiting chalk. Alternatively, you can also get a white polishing stone, which you can also get in the drugstore.

The good old scouring milk does it too, by the way. Just like the often mentioned home remedies citric acid or cola. Let both work for a short time and then wipe off and dry immediately. Only the rust should be loosened. However, prolonged exposure to the acid can worsen the pitting.

It is also important that you do not use a pot sponge, but a soft cloth or sponge made of foam.


The manufacturers of dishwashers have little influence on whether rust film forms and spreads in the machine. Basically it depends on what you put in it.

To avoid pitting corrosion, however, Miele recommends running the QuickPowerWash or Schnell 40 ° C program after you have refilled the salt container.

The easiest way to do it is to make sure, when you buy the equipment that goes into the dishwasher, that it is really dishwasher-safe.

Some people hand wash all the knives in the cutlery. That would be too time-consuming for me. I prefer to invest a little in the quality in advance, even if it has its price.

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