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Using a dishwasher simplifies housework and helps save time. It also protects the environment, because a dishwasher uses less water and energy than doing the washing up by hand. Fundamentally, all dishes marked dishwasher-friendly or dishwasher-safe by the manufacturer can be washed in a dishwasher. If you follow some simple rules and use the right product from Somat, your dishes will come out of the machine spotless and shiny clean every time.

Depending on the machine type, some programs can be selected directly with a rinse cycle. These programs typically include more intensive cleaning. Corresponding information can be found in the user instructions for your dishwasher, or on the website of the manufacturer. The pre-wash/cleaning function initially rinses off food residues that can easily be removed entirely with cold water. The main wash program then starts with fresh water, before the detergent is automatically added from the dosing chamber. Depending on the program selected, the water is heated to a temperature between 35°C and 75°C. The wash program lasts between 15 and 90 minutes, and ends with pumping out the dishwater.

Intermediate rinse
All programs include an intermediate rinse cycle. This intermediate rinse cycle is necessary in order to remove remaining dishwater and dirt, and to prepare the dishes for the final rinse. The intermediate rinse ends with the water being pumped out.

Final rinse
All programs except the pre-wash program include a final rinse function. The water flows into the machine and is heated to a maximum of 75°C in standard programs. During this process, the rinse aid is automatically added from the dispenser. With Somat 7, Somat 10 and Somat Gold, no additional rinse aid is required, because it is already integrated into these products.

All programs, except for the very fast “Rinse only” cycle for fast cleaning (e.g. of glasses only), also include drying. The residual heat from the final rinse helps to dry the dishes. Drying generally takes between 20 and 70 minutes.

The majority of dishwashers are suitable for use of Somat special salt. These machines automatically regenerate the integrated water softener with the aid of the salt solution in the reservoir. When using Somat 7, Somat 10 or Somat Gold, the addition of dishwasher salt is not required, provided that the hardness of the water does not exceed 21°dH (German hardness scale).

First you can reduce the washing temperature to 50°C or 55°C. This saves around 84 kWh of electricity and 1497 litres of water per year.

You can also use an automatic program. This will find the best settings for whatever dishes are in the machine, and will use the right amount of water and energy. Load and sort the dishes as recommended by the manufacturer. Check and clean the filters on the drain regularly. And last but not least: Run the dishwasher only when fully loaded.

Automatic programs optimally adjust the settings to the dishes in the machine, and use the right amounts of water and energy, which helps protect the environment.

When used as intended, modern detergents for dishwashers can achieve the desired degree of cleanliness at just 50°C or 55°C and with automatic programs.

The terms “dishwasher-friendly” and “dishwasher-safe” are often used to describe dishes. The term “dishwasher-friendly” has no official definition, and is used by dish manufacturers based on experience. By contrast, there are defined tests and measurements for use of the term “dishwasher-safe” on non-metallic dishes, which are defined in two international standards, EN 12875-1 and -2. The results of these tests are indicated using a standardised symbol, which displays the maximum number of wash cycles that the relevant dish can survive undamaged. As yet there are no such standardised tests for dishes made from metal. Pots and pans that are made from non-magnetic metal, or which are made from a single material, can generally be washed in the dishwasher without problems; they are often marked “dishwasher-safe”. In the case of objects made from various materials, e.g. a body made of metal and a handle made of plastic, if in doubt contact the manufacturer.

Dishes are made from many different materials. How an item reacts when washed in the machine depends on its material composition and the manufacturing process.

Stainless steel
Cutlery, pots, pans, plates, spatulas, ladles and sieves are often made from stainless steel. Unlike iron or “normal” steel, stainless steel does not rust. This is achieved by alloying iron with various proportions of other metals, particularly chrome and nickel. Stainless steel can generally be washed in the dishwasher.

Glass is appreciated in household goods because of its special properties, such as its transparency, the way it splits and reflects light, because of its shine, its impermeability, and its resistance to chemicals. Glass can generally be washed in the dishwasher.

The items most frequently washed in dishwashers are silver cutlery. Since decorative service plates, dishes and placemats, tea glass holders, and salt and pepper pots have a significantly thinner silver plating and often have an additional layer of clear varnish, they are not suitable for the dishwasher.

Unpainted items made from wood, such as non-glued wooden spoons, can be washed in the dishwasher. This bleaches them, however, and they often become somewhat rougher. Wooden boards that have a larger surface can develop tension cracks. Wooden handles on cutlery become dull or cracked. Items made from glued wood are not suitable for cleaning in the dishwasher, because they can swell up, and the surface becomes faded, rough and cracked. Painted wood is also not suitable for cleaning in the dishwasher. The wood swells, which causes the paint to flake off.

Dishes made from fine ceramic can be subdivided into four groups: pottery, earthenware, porcelain and fritware. As a rule for determining if these materials are dishwasher-safe: the harder and less porous the material, the more dishwasher-safe it is.

Plastic items can easily become deformed in machines with exposed heating coils, if they are placed in the lower rack. Plastic items should therefore always be placed in the top of the dishwasher. Under unfavourable conditions, coloured food residues such as tomato juice, ketchup, carrot juice, beetroot, and red cabbage, can stain plastics.

Silver and stainless steel cutlery can be washed in the dishwasher at the same time. However, the various types of metal should not touch one another during the wash cycle, because otherwise they can tarnish or become stained.

Unalloyed aluminium reacts with both acids and alkalis, and tends to develop surface changes even just through contact with water. Black spots on aluminium are known as “water spots”. Aluminium of this kind – such as is often used in garlic presses – is not suitable for the dishwasher, and the damage caused is often irreversible. In the case of pans and pots made from aluminium, it is a good idea to ask the manufacturer whether they are dishwasher-friendly or dishwasher-safe. Exposed aluminium layers in the base of pots and pans can also exclude washing in the dishwasher.

Before you place dishes in the dishwasher, scrape off all easily removable food residues. Pre-washing in the sink is neither necessary nor environmentally friendly. The only exception is residues that do not dissolve in water, such as spinach, cigarette ash, or shredded herbs. These should be washed off, because otherwise they could get stuck to other dishes.
The dishes must be stable inside the dish racks. Glasses in particular must be positioned securely in order to avoid bumping against each other and thus being damaged.
Cups can be placed in the corners of the dish rack, while deep dishes are better placed in the middle. Items must never be placed loose over neatly stacked dishes, because this can result in “spray shadows” where the water cannot reach the stacked items.

Ensure that the spray arms can rotate freely.
Large items belong in the lower dish rack, while small and easily breakable items such as glasses and cups should be placed in the top rack.
The cutlery is not sorted, and is placed in the cutlery basket with the handles pointing downwards. If your machine has a cutlery drawer, you can sort the cutlery when placing it in.
In machines with exposed heating coils, plastic parts can easily become deformed if they are placed in the lower rack. Plastic items should therefore always be placed in the top of the dishwasher.

Leave the dishwasher slightly open for a few minutes after the end of the program to allow the dishes to cool down. Start emptying from the lower dish rack, so that water from the upper rack cannot drip onto the dry dishes.

When used properly, a dishwasher requires no particular care, because the interior of the dishwasher and the dish racks are automatically cleaned during the program cycles. The filter unit should however be cleaned regularly.
Inadequate dosing of the detergent, neglecting to scrape large or very fatty food residues off dishes, or selecting programs not appropriate to the level of dirt, can cause fatty dirt residues or other deposits from food residues to stay in the interior of the dishwasher and impair the cleaning performance by obstructing the flow of water through the system. In this case, and if the cleaning performance is no longer satisfactory, the interior of the dishwasher and the spray nozzles of the spray arms should be cleaned.

Regular cleaning cycles with Somat machine cleaner (about once every month or two) keep the visible and non-visible water-carrying parts of the dishwasher clean.
For cleaning the side edges of the dishwasher, as an alternative to Somat machine cleaner, you can use a little all-purpose cleaner. Simply apply this with a damp cloth and then wipe the dirt off.

The drain hose needs to be connected above the siphon that serves as an odour trap. There should also be no kinks in the hose.
It may be that the selected wash program is not sufficient for the dirtiness level of the dishes. This results in deposits in the filters.
Solution: Hang a bottle of Somat intensive machine cleaner in the dishwasher, and allow the machine to run through one of the most intensive wash programs.
Deposits on the door seal can also be a cause. Solution: Moisten a cloth with intensive machine cleaner and clean the door seal.
If odours develop because the machine has not been used for an extended period, this can be prevented with Somat Deo-Perls®. Somat 7, 10 or Gold tablets can likewise help to neutralise unpleasant odours, ensuring a fresh-smelling machine after each wash cycle.

Almost all household dishwashers can be connected to a hot water supply. As a general rule, the maximum inlet temperature should not exceed 60°C – for further information, it is best to contact the manufacturer of the dishwasher. Connecting a dishwasher to the hot water supply can save energy, because the water no longer needs to be electrically heated during the washing process. The amount of energy actually saved depends on the inlet temperature of the water, and the room temperature.
The cleaning performance of Somat products has proven very effective for machines with hot water inlets. Even temperature-sensitive components like enzymes develop their full power: the hot water in the first cycle (pre-wash or main wash, depending on which program is selected) is cooled to around <55°C by the temperature of the dishes and the inner walls of the machine.

When you use a multifunctional tablet (e.g. Somat 7, Somat 10 or Somat Gold), no additional rinse aid is needed. And at a water hardness of up to 21°dH (German hardness scale), no additional regenerating salt is needed. If you have hard water, you should use regenerating salt to protect your machine and achieve the best dishwashing results. Depending on the machine type, a warning light may indicate a lack of rinse aid or insufficient salt. This indicator can be ignored if multifunctional tablets are used correctly.

Washing-up liquid is not suitable for use in dishwashers. These products generate foam, which can penetrate the base of the machine and trigger an “aquastop”. You would have to call the customer service and have the machine repaired by a technician. For the same reason, dishes pre-cleaned by hand should be rinsed off thoroughly before they are placed in the dishwasher.

Almost all household dishwashers can be connected to a hot water supply. As a general rule, the maximum inlet temperature should not exceed 60°C – for further information, it is best to contact the manufacturer of the dishwasher. Connecting a dishwasher to the hot water supply can save energy, because the water no longer needs to be electrically heated during the washing process. The amount of energy actually saved depends on the inlet temperature of the water, and the room temperature.
The cleaning performance of Somat products has proven very effective for machines with hot water inlets. Even temperature-sensitive components like enzymes develop their full power: the hot water in the first cycle (pre-wash or main wash, depending on which program is selected) is cooled to around <55°C by the temperature of the dishes and the inner walls of the machine.

70/75°C intensive program
Normally and very dirty pots and pans

65°C normal or universal program
Dried-on food residues

50/55°C normal or universal program
Normally dirty dishes

45/55°C energy-saving/eco program
Normally dirty dishes (program may take longer than the normal program)

35°C – 45°C program for delicates/glass
Slightly dirty, very sensitive dishes (particularly glasses)

35°C – 60°C fast/short program
Slightly dirty dishes without dried-on food residues (program takes less than an hour, but may result in higher energy consumption)

The causes could be that the wrong program was selected, that the dishwasher was not loaded correctly, or that there were insoluble residues on the dishes. The best way to avoid unsatisfactory dishwashing results is to scrape or wipe bulky food residues off dishes before washing, and to then place them into the dishwasher immediately after use. Check whether the machine was loaded correctly. The spray arms must be able to rotate freely, and the openings must not be blocked. Follow our tips on loading the machine.

Sandy residues in glasses, cups or narrow containers result from excessive levels of dirt or washing temperatures that are too low. Tall, narrow glasses should not be placed in the outer corners of the upper rack, because then the dishwater is not able to reach all parts freely. If food residues have not been washed away, they will often have been in “spray shadows”, i.e. these items were covered by other dishes. Check the filter system and spray nozzles regularly, and remove any blockages in order to avoid deposits of food residues accumulating.

Black tea forms a skin when it is left to stand, which can stay behind on the inside of the cups. Stains caused in this way can be particularly difficult to remove if the local water is particularly hard, as well as with certain types of tea. Tea stains are removed using high doses of detergent or a Somat multifunctional tablet on the 50/55°C wash program. Somat 7, 10 or Gold tablets can remove tea stains at low temperatures.

Greasy residues accumulate in the filter and in the dishwasher when very greasy dishes are washed frequently using short or fast programs. The wash program should always be selected depending on the level of dirt on the dishes. Excessive greasy residues on dishes or pans should be scraped off, e.g. using cutlery or a paper towel, before the dishes are loaded into the dishwasher. In order to clean the inside of the dishwasher easily, we recommend using Somat machine cleaner (if available in your region).

When regenerating salt is used for softening the water, there may be a white, water-soluble coating on the dishes after washing. This can have the following causes:

  • The lid of the salt chamber is not properly closed, causing salt water to be pressed into the inside of the dishwasher. In this case, you should close the lid firmly.
  • The lid may have a hairline crack and need to be replaced.
  • During refilling, excess salt may have got into the inside of the machine. In this case, empty the machine and run it through a short cycle without any dishes.

The tarnishing is probably the result of the food the cutlery was used to eat. Food residues containing sulphur, such as mustard, eggs, vegetables, fish etc. can result in silver becoming tarnished. In the dishwasher, food residues containing sulphur have more time to react with the dishes than when washing up is done by hand. The silver protector in Somat tablets significantly reduces tarnishing of silver caused by traces of sulphur compounds from food residues. If a lot of food residues are present or if the machine is only used irregularly, we recommend that silver should be washed by hand immediately after use, or the machine should be run on a cold pre-wash cycle as soon as possible. You should avoid direct contact between silver and stainless steel in the dishwasher. However, it is not only external influences that cause silver to become tarnished. The composition and processing of the silver plating plays a decisive role. For example, 800 silver can tarnish to golden or pale brown due to its high copper content (200 parts in 1000). It is therefore less suitable for the dishwasher. If it was electroplated with silver, it will behave like a 90g or 100g silver plating. Very old silver cutlery whose silver plating has worn away over time, sometimes to the point that the base material is visible, tarnishes more easily. Such cutlery should no longer be washed in the machine. Overall, it is not possible to entirely prevent silver from tarnishing. Stains on silver items can be removed using a metal polish.

These “rainbow” colours are a form of tarnish, caused by certain types of food such as cauliflower, celery, kohlrabi, mushrooms, potatoes, or cooked fish. It may be that the water absorbs corresponding substances and causes discolouration of other dishes in the machine. These iridescent colours are a very thin coating that settles on the steel. They are completely harmless to health, and can be removed with machine cleaner or a metal polish.

Such rust spots, known as flash rust, can appear on stainless steel dishes or cutlery, and are generally transferred from other sources. These could include screws made from non-stainless steel, which have been used to affix handles on pots and pans. Other sources of rust can include enamelled kitchen utensils, peeling knives, tea strainers, or other kitchen utensils made from low-alloy steel. Frequent sources of rust are dish racks whose plastic coating has been damaged, allowing the metal rods underneath to rust. The rust that has developed is spread around the machine via the dishwater, and adheres to stainless steel elements. The dishwasher detergent itself cannot cause rust. In rare cases, rust could also be brought in by the tap water.

The most common type of corrosion in stainless steel is pitting corrosion, which has a destructive effect on the material. This primarily affects the blades of knives. Pitting corrosion mostly starts with pinprick holes that are not yet visible to the naked eye. When the holes become larger, it is entirely possible for these to turn into destroyed areas several millimetres in size, which become dark grey or black and have a grainy structure. The cause of this corrosion is always destruction of the surface protection layer. This destruction is caused by chlorides, which can be contained in drinking water and food residues in the form of cooking salt. Acids in food can additionally amplify the effect. It is important that when the salt chamber of the water softening system is refilled, no dishwasher salt is left behind for extended periods on the bottom of the container or in other areas of the dishwasher. This can be prevented by a pre-wash cycle, in newer machines a short program, so that the “excess” regenerating salt or displaced salt water can be rinsed away. Alkaline products such as cleaning agent solutions do not cause pitting corrosion on stainless steel surfaces.

The development of glass corrosion, which results in milky cloudiness, depends on the type of glass and the washing conditions. Despite its chemical resistance, glass can be affected over time, even by clear water or aqueous solutions. As a result, substances get washed out, and the glass looks weathered. This effect is amplified by the frequent changes between wet and dry phases, and by temperature fluctuations (during the intermediate rinse cycle). It can nevertheless take a very long time before visible effects such as cloudiness or milky stripes develop as a result of dishwasher use. Because glass is typically so shiny and transparent, irregularities become visible suddenly and all at once. There is no connection with the detergent used. This type of glass corrosion can occur with any dishwasher detergent. However, the Somat multifunctional tablets have an integrated protection function, which protects glass against corrosion for longer.

Here is another helpful note for the future: When you buy new glasses, pay attention to markings or specifications of whether they are dishwasher-safe. Some manufacturers guarantee glasses are dishwasher-safe for a certain number of wash cycles.

Their water-repellent surface makes it more difficult to get plastic items wet. During drying, this results in the formation of droplets. In addition, plastic only absorbs warmth with difficulty. It therefore dries slower than other materials. Depending on the (surface) conditions of the plastic items (age, roughness, scratches etc.) and the drying power of the dishwasher, some items may still be damp at the end of the program.

Scratches are always caused by mechanical contact with the glass surfaces. Almost all drinking glasses that get used every day have such damage. During washing, scratches and other damage are caused above all when glasses bump against one another or against other hard objects. This either happens when loading the machine, or because they are too close together in the dish rack. Circular scratch marks often appear because the glasses also rotate while being washed. Scratches can occur individually and distributed around the glass.  They can merge so that they form a white spot or ring.  “Chatter marks” are a preliminary form of damage that is not normally visible to the naked eye. Under the microscope, however, fine fractures can be seen that lie over one another like scales. Only after being washed in the machine many times do they become visible as fine cracks. In general, the scratch-like marks on glass are not initially visible to the naked eye. The more often the glass is washed in the machine, the more clearly visible they become, because water and aqueous detergent solutions penetrate into the scratches or fine cracks. This cracks out glass particles that have already been loosened. This process is promoted above all by the abrupt drop in temperature between the hot cleaning cycle and the cold intermediate rinse cycle.

Further information on the new Globally Harmonised System (GHS) of hazard symbols, which are used on Somat products from Henkel, can be found at .