There is a kettle in every kitchen. It doesn’t matter if it’s an old metal appliance or a modern electric one - any of them requires timely care, not only outside, but also inside. Here the question comes to the fore: “How to clean the kettle from scale and why do it?”

That's what we'll talk about today, and at the same time we'll figure out what measures can be taken to minimize the appearance of an unpleasant sediment.

Scale is formed due to the content of salts in water, mainly calcium and magnesium carbonate. Over time, they are deposited on surfaces that come into contact with water: in kettles, thermo pots, dishwashers and washing machines.

And no matter what good teapot you choose, sooner or later you will still encounter the problem of white hard deposits. In ordinary kettles, it covers the bottom and walls, and in electric kettles it also covers the heating element, significantly worsening thermal conductivity.

In this case, the water heats up longer, and in electric kettles, the presence of sediment can lead to breakage. To carry out its function, the spiral or disk has to heat up more and more each time. This leads not only to an increase in electricity costs, but also provokes the rapid development of the resource of the part. Eventually the heater will just burn out.

Scale is dangerous to human health, since its particles penetrate the body and provoke the development of kidney disease, osteochondrosis and gout. In addition, under the influence of salts, the taste of drinks changes, a whitish precipitate appears in the glass.

How to deal with scale and what not to do?

Fortunately, knowing the nature of the occurrence of an unpleasant sediment, it turns out to be quite easy to fight it. Plaque is afraid of organic and inorganic acids: under their influence, it becomes loose, so removing it is not difficult. Armed with this knowledge, you can get to work.

But first, let's talk about what not to do:

• Remove scale mechanically with a knife, scrapers or a metal sponge. Thus, you will spend a lot of effort, and perfect result still won't get it. In addition, there is a high risk of damage to the device.
• Do not use harsh chemicals such as Whiteness. It will remove the plaque, but it will be very difficult to wash off the remnants and get rid of the pungent odor.
• Powders with large granules can scratch the surface, scale will form even faster.

Special funds

The chemical industry has developed special formulas for easy softening and descaling. These are, for example, Cinderella, Antinakipin, Flat, Bosch and many others.

They are easy to use: in most cases, it is necessary to dissolve the product in water, boil and leave for a while.

Please note that some formulas have a different way of being applied. Be sure to read the instructions!

Folk methods

Why spend on household chemicals, look for where it is sold, if there are no less effective products in every kitchen?

After using any of these methods, thoroughly rinse the kettle and boil it at least once. clean water. This is necessary to remove the remaining particles of the product and the smell.

Soda

A gentle method that is suitable for all kettles, including aluminum and enameled ones. You need to mix 500 ml of water with 1 tbsp. l. soda (preferably soda) and boil over low heat for 30 minutes. After that, wash the device inside well with a sponge or cloth, if there is a need to repeat the process.

Vinegar

A rather aggressive method that will help in the fight against old deposits in metal, glass and plastic kettles.

It is necessary to pour 500 ml of water and let it boil. Then pour about ¾ cup of table vinegar or 1 - 2 tbsp into boiling water. l. 9% vinegar essence and leave for 1 hour. Periodically, you need to check how the peeling process is going on, and as soon as all the scale has gone, wash the kettle.

Be sure to wear a mask and open a window to protect your airways from the vinegar fumes.

Lemon acid

Suitable for quick cleaning of glass, plastic and stainless steel appliances.

Bring to a boil 0.5 liters of water and dissolve 1 - 2 tbsp. l. lemons. Let it cool down completely and repeat the procedure if necessary.

You can take into service not only powder, but also fresh lemons.

To do this, cut half a citrus into pieces and put in a teapot. Otherwise, the recipe for use is the same as with citric acid. But as a bonus of this technique: a pleasant citrus aroma after processing.

Brine

The composition of the brine from cucumbers or tomatoes contains acid, which means that it can be used to remove plaque in enameled teapots and stainless steel.

To do this, filter the liquid through a sieve and boil. The brine level should be no more than ⅔ of the volume of the kettle. After that, let the liquid cool and drain it.

cleaning

At home, you can prepare a mild remedy for any teapots. It is suitable as a prevention of plaque formation or if there are few deposits. Will fit potato peelings or peel from apples and pears.

Remember to thoroughly wash the potato peelings off the ground.

We shift the peels into a kettle, fill with water and boil. Let cool, remove the remaining scale with a sponge.

For electric kettles, you can apply the following recipe: put the cleaning in a saucepan, boil and pour the finished broth into the device. Heat again to 100 ° C, let stand and rinse.

Carbonated drinks

Suitable for stainless steel cookware and electric kettles. In enameled and tin, use with caution.

Don't use colored sodas like Fanta or Coca-Cola on plastic devices because they can stain the surface. Better take a colorless drink: 7UP or Sprite.

To learn more about how to clean your kettle with Coca-Cola, watch this video.

In order to use the soda, first open it, let the gas come out. Then pour the drink into the kettle and let it boil. Cool down and clean the appliance.

Triple strike in advanced cases

With a very persistent draft, a three-phase system will help:

1. Pour water and dissolve one tablespoon of baking soda in it. Boil, and then drain the liquid.
2. We fill the kettle with water again, but now we add citric acid (1 tablespoon) there. Let it boil for about half an hour and pour out the solution.
3. Now pour 0.5 cups of vinegar into clean water and boil again for at least half an hour.

This method will help soften and remove the most persistent plaque. But it is better not to bring the dishes and appliances to the point where they need such cleaning.

Prevention of scale formation

To prevent scale from reappearing, follow these recommendations:

• Install a filter or buy bottled water.
• Pour the leftovers after boiling into another container, and rinse the kettle thoroughly.
• Do not heat the same water repeatedly.
• Pour a solution of citric acid at least once a month. Just let it stand for about an hour and rinse. You can also use cleaning or brine.

Conclusion

Scale phenomenon, of course, unpleasant, but inevitable. If you fight it regularly and do not let it firmly settle on the walls of your kettle, then it will not cause any problems.

Rinse the kettle regularly, dedicate half an hour a week to preventive cleaning, then salt deposits will not even have a chance to settle in your kettles.

I think that now you will not meet such a family that does not have a kettle in the kitchen. Some people prefer to heat water the old fashioned way, using metal utensils. For whom every minute counts, they buy modern electrical models. They have both their advantages and disadvantages. Water begins to boil after a couple of minutes, but scale forms several times faster. This problem is especially relevant for glass electric kettles. Their glass begins to fade due to the formed plaque, the heating element is covered with layers of scale, which are unpleasant in appearance. Because of the transparent glass, this is all clearly visible, cleaning such a kettle has to be done several times more often. Newfangled filters do not save you from this scourge, only to delay its “maintenance”. If the heating element is not cleaned in time, sooner or later it will fail. In this article, we will show and tell you how to properly and quickly clean glass Electric kettle from scale at home, using folk remedies.

How to descale a glass electric kettle with vinegar.

Vinegar is an effective and cheap remedy with many useful properties in household. It is used to remove fungus, stains, unpleasant odors, all types of bacteria, in washing floors, carpets, etc. Today we will use it to clean the scale from a glass teapot.

1. Purchase white transparent vinegar (wine or apple cider vinegar will not work for us).
2. Mix it in equal proportions with water.
3. Pour into a glass electric kettle, boil our solution several times.
4. Do not immediately pour out, let it brew for 1 hour until the liquid has cooled completely.
5. Pour out and carefully wipe everything with a sponge, if the deposits were small, this will be enough, if not, then you can walk with an old toothbrush.
6. Rinse thoroughly with water, drain it after the first boil, as a characteristic aftertaste may remain.

The only disadvantage of this method is bad smell, which comes from him during cleaning. But be calm, it does not eat into things and quickly disappears.

How to clean a glass electric kettle with citric acid.

I think the beneficial properties of citric acid in getting rid of scale are known to everyone. It's not expensive and you can get it at any grocery store. Unlike vinegar, there is no unpleasant odor when working with lemon.

Procedure.

1. Pour water into the kettle to the maximum possible level, add citric acid at the rate of 3-5 tablespoons per liter.
2. We boil our composition several times.
3. We are waiting for the water with lemon to cool down.
4. Drain, rinse under running water so that all lumps of scale fly off. Then wipe with a sponge or, in case of strong deposits, clean with an old toothbrush.

Worth knowing! It is not necessary to use citric acid in bags, in powder form. You can squeeze one whole fresh lemon into a teapot or add bottled lemon juice.

A solution of baking soda.

Usually baking soda is in the kitchen of every self-respecting housewife. At its core, this is an alkali that is not harmful to humans, which well crushes the deposited salts, they are present in the scale and are clearly visible, especially in glass electric kettles.

1. We dissolve baking soda in water, 3 tablespoons will be enough, but the more, the better. Stir thoroughly and pour our solution into a glass teapot.
2. Boil several times.
3. We are waiting for the water to cool completely.
4. Drain and clean with a soft sponge, if the deposits were abundant, use a kitchen brush.
5. Rinse thoroughly.

Soda + vinegar.

Using these two products will be much more effective than cleaning each of them one by one.

1. Add 3 tablespoons of vinegar and 5 soda to the water.
2. We fill in our composition and carry out boiling.
3. We wait until the water has completely cooled, then drain it.
4. We pass with a sponge or brush to finally remove all deposits.

Lemon + vinegar.

Also a very effective combination of anti-calc products.

1. For 1 liter of water, we add 3 large spoons of citric acid or squeezed lemon juice + 3 tablespoons of vinegar.
2. Pour the resulting solution into a glass teapot.
3. We set the boiling mode, it is advisable to do this at least a couple of times.
4. Drain the solution and clean the surface with a kitchen sponge or an old toothbrush.

Lemon + soda.

Similarly, you can mix citric acid and soda, such a composition will give a double effect of descaling. Pour water into our device, add lemon juice or citric acid in powder 3 large spoons and 5 tablespoons of baking soda, boil several times, then rinse and walk over the surface with a sponge.

Soda.

Many people know useful property carbonated drinks that contain phosphoric acid. With their help, in addition to limescale and scale, you can also remove rust from the surface. Make sure your lemonade contains E338. For our purposes, Sprite is ideal, as it is transparent and will not leave marks, especially for electric glass kettles.

Pour lemonade into the device, you can mix it with water in proportions of one to three. Boil several times, then rinse and remove the remaining scale with a kitchen brush.

If your kettle is heavily scaled, do not dilute the soda with water.

Alternative methods.

Well-known grandfather's way. You can use the peel of lemon, orange, apples and potato peels. Load them into a kettle, fill with water and boil several times. Then rinse and go over with a stiff-bristled kitchen brush to completely remove the limescale.

Special tools from the store.

Antinakipin. The composition of this tool includes simple organic acids, which do not harm the human body. Enough effective remedy for those who don't want to bother with citric acid, soda and vinegar. It is cheap, in chain stores I met small bags of 5 rubles.

Other similar means. Be careful when choosing them, read the composition. If you want to use a glass electric kettle for cleaning, make sure it does not contain Trilon. There have been cases when it corroded the nickel coating of the heating element.

Prevention of scale formation in a glass electric kettle.

Scale will appear sooner or later, but it is possible to delay its appearance for a significant period, it is enough to follow simple tips.

• Pass water through a filter (for example - Barrier) before pouring it into the kettle.
• Small and fresh scale deposits are easily removed even by the most simple means. Perform preventive cleaning at least once a month.
• Do not let the water stagnate in the appliance for a long time, after each use it is recommended to pour out the water.
• When making tea, you can pour a small amount of lemon juice directly into boiling water. Thus, the prevention of plaque formation will be ensured, and then you can not cut the lemon into the tea at the exit.

Scale appears due to impurities contained in poor-quality water. During boiling, they settle on the walls of the kettle and spoil the taste of hot drinks. Also, scale does not conduct heat well, so a dirty kettle will boil longer.

How to clean a kettle with vinegar

The method is suitable for very dirty teapots made of plastic, glass, stainless steel.

You will need:

• ½ liter of water;
• 1 cup 9% vinegar or 2 tablespoons 70% vinegar essence.

Heat water in a kettle, and then pour in vinegar or vinegar essence and leave the solution for an hour. During this time, the scale will soften. Rinse the kettle from the inside with a sponge, boil clean water again and drain it.

How to clean the kettle with lemon or citric acid

The method is suitable for electric kettles made of stainless steel, plastic or glass with a moderate layer.

Not suitable for enamel and aluminum kettles.

You will need:

• ½ liter of water;
• ¼ lemon or 2 tablespoons citric acid.

Heat water in a kettle and put a piece of lemon or citric acid into boiling water. Leave the scale to soak for 1-2 hours. Rinse the teapot with a sponge and rinse thoroughly. After the first boil, the water will need to be drained.

How to clean a kettle with baking soda

The method is suitable for any kettles.

You will need:

• ½ liter of water;
• 1 tablespoon of baking soda.

Stir the baking soda in a glass of water so that it dissolves completely. Pour the resulting liquid into the kettle, add the remaining water and boil it. Wait half an hour or an hour and heat the kettle again.

Now you can wash the kettle and boil clean water in it. True, after it will have to be poured.

How to clean a kettle with soda

The method is suitable for stainless steel kettles heated on a stove.

Not suitable for aluminum, enamel and electric kettles.

You will need a bottle of any lemonade. Most famous variant- cola, but it is better to use a colorless drink (it is important that the composition contains citric acid).

Let an open bottle of lemonade sit for 2-3 hours to eliminate gas bubbles. Then it's simple: pour the drink into the kettle and bring to a boil. Then thoroughly wash and rinse everything.

How to peel a kettle

The method is suitable for enameled and metal teapots with a weak layer of scale.

Not suitable for electric kettles.

You will need:

• ½ liter of water;
• skin 2-3, apples or pears.

Rinse the cleaning from dirt and sand, put them in a kettle and fill with water. Boil the liquid and leave to infuse for one to two hours. A light layer of scale will come off on its own, persistent pollution rub with a dishwashing sponge. After rinsing, the kettle will shine like new.

If you have a particularly capacious kettle, and scale has accumulated on the walls, take more water than indicated in the recipes. The liquid must cover the contaminants completely.

How to keep the kettle clean for a long time

1. Pour soft water into the kettle. If you don't buy bottled, use a filter. Or at least stand your tap water for a few hours to allow the impurities to precipitate.
2. Boil water in the kettle no more than once. Better fill it fresh.
3. Rinse the inside of the kettle at least once a day. And ideally before each use.
4. For prevention, once a month, boil a filled kettle with one tablespoon of citric acid.

Electric kettles can be expensive and cheap, with a wide variety of filters, but nothing saves you from the scale that regularly forms on the walls and bottom of the electric appliance.

The formation of problems begins at the most vulnerable place - the heating element. Citric acid from scale in the kettle will help get rid of the problem quickly and safely.

Water filters do an excellent job of purifying water from heavy metals and chlorine, but this does not apply to lime, and although the amount of sediment will be less, it will not work out completely.

It turns out that the precipitate obtained during boiling is a poor heat sink. When the heating element, which is made of steel, heats up well, it cannot give off heat to the liquid - adhering particles block the path to it. If there is nowhere to give off heat, the element continues to accumulate it, overheats greatly and eventually simply breaks.

But the process of sedimentation is dangerous not only for economic reasons. Each water has a certain amount of salts. If it is hard, there is a lot of salt. When boiling, they create a salt coating, accumulating on the walls and the heating element, and fall into our cups.

All this enters the kidneys, liver and stomach, creating many problems in the future. That is why you need to know how to remove scale in a kettle with citric acid.

Why is descaling a kettle with citric acid convenient and safe?

There are chemical products for removing sediment from an electric kettle, but they are not safe for health. After use, the device is boiled for a long time and persistently, washed, boiled again. But a metal thermal element after the action of salts always remains dotted with cracks, scratches and chips invisible to the eye. In them chemical agent can leave its particles.

Cleaning the kettle from scale with citric acid is gentle for him and safe for humans. It is reliably washed out after the first boiling, and does not pose a danger to the body, especially in the negligible amount that may remain after processing an electrical appliance.

In addition, descaling the kettle with citric acid is very cheap, and you can purchase the product at any grocery store, at any time you want to determine for this work.

How to clean the kettle from scale with citric acid

There are several options for cleaning by boiling and without it, with lemon.

Boiling

Remove scale in the kettle with citric acid by boiling. This method is suitable for a large number sediment that is already tightly compressed. The process is divided into the following steps:

• Before cleaning the kettle from scale with citric acid, it is first necessary to wipe the walls and the heating element from soft deposits. You can do this with a hard rag, but in no case should you use hard, and especially metal, washcloths. After that, rinse well with cold water.
• Depending on the amount of plaque, use 20-40 gr. funds for one boil. In ordinary store packaging, this is 1-2 things. Cook them.
• fill the electric kettle clean water 2/3 of the capacity, open the prepared packages and pour into the liquid.
• Put the appliance to boil. If he is with circuit breaker, a few minutes after switching off, bring to a boil again. If there is no machine, boil water for 2-3 minutes.
• Leave the kettle on for a few hours. After that, pour out the water, carefully remove the softened sediment (without the help of sharp objects). In case of incomplete cleaning, repeat the procedure.
• Rinse thoroughly from sediment, pour clean water, boil it and pour it out. Then the device is ready for operation.

No boiling

If the electric kettle is cleaned at least once a month (twice with hard water), you can apply milder measures and remove scale in the kettle with citric acid without boiling. For this it is enough:

• AT warm water dissolve a packet of citric acid.
• Fill the container with a solution and leave for 4-5 hours, preferably overnight.
• Rinse the device from sediment.
• Pour in clean water and boil. The electric kettle is without sediment and ready for use.

regular lemon

There are small children in the house, and there are doubts about how to wash the kettle from scale with citric acid, while being sure of the safety of the baby? There is a way out that is a little more expensive, but ideal in terms of safety for the body, even for babies. To do this, clean the kettle from scale with citric acid own production. Powder, of course, does not have to be made. It is enough to have an ordinary lemon available:

• It is cut into thin circles along with the skin.
• The electric kettle is filled with 2/3 water, chopped rings are lowered into it and all this is put to boil.
• The softened sediment, together with the remaining lemon, is removed from the container, the device is thoroughly rinsed.

Lemon from scale in a teapot - great idea, although a little more expensive. The method is not only harmless and fast (no final boiling is needed), but also has another interesting property - the boiling container gets a pleasant lemon smell for a while. As for the amount of the product, it must be varied depending on the contamination.

Half a lemon is enough for regular cleaning, but to descale the electric kettle with natural citric acid in advanced cases, you will have to chop 2-3 pieces and fill the floor of the container with mugs.

Descaling the kettle with citric acid is best done frequently. This will significantly extend the life of the electrical appliance, preserving not only its performance, but also your health. No sediment - no sand and kidney stones, no infection and no load on the liver.

Knowing how to clean scale with citric acid in a kettle quickly and carefully, you can always stay healthy for both the appliance and its owner.

Read more about how to clean the electric kettle with citric acid (video)

Arina Piskareva

Laboratory employee of the Department of Bioengineering, Moscow State University

Scale is mainly composed of calcium and magnesium carbonate. When interacting with citric, acetic, orthophosphoric or other acids, sparingly soluble carbonates of alkaline earth metals are converted into easily soluble salts. For example, acetates. Therefore, acidic substances are effective in the fight against scale, and to enhance the reaction they need to be heated.

Soda, when interacting with water, gives molecules of carbonic acid, which, in turn, reacts with insoluble calcium and magnesium carbonates, turning them into soluble hydrocarbons. And they are easily washed off with water and removed with a sponge.

1. How to clean scale with citric acid

• Suitable for any kettles, coffee machines, irons, washing machines.
• Proportions: kettles, coffee machines and irons - 10 g for every 100 ml of water; washing machines - 50 g for each kilogram of load.
• pros: environmental friendliness, safety, availability, pleasant aroma.
• Minuses: does not cope with old, thick scale.

Fill the kettle with water about ¾ - so that the liquid covers the plaque on the walls and heating elements, but did not splash out when boiling.

Pour citric acid (100 g of powder for every liter of water) into the kettle and boil.

Leave until completely cool. Drain the water, remove the remaining plaque with a sponge and wash thoroughly.

How to descale your coffee machine

For the coffee machine, it is necessary to prepare a solution of citric acid based on the volume of the water tank. For example, if the coffee machine is designed for 2 liters, you will need 200 g of citric acid.

Pour the hot solution into the tank and leave for 60 minutes.

After one hour, start the coffee preparation program without coffee itself. Drain liquid through dispensers.

Then start the coffee machine with water only, without citric acid. As soon as you drain the boiling water, you can use the device. If the tank of the coffee machine is removable, remove the remaining deposits under running water.

After the procedure, rinse the iron tank with running water, and wipe the sole ammonia or nail polish remover.

To remove plaque from the heating elements and the drum, you will need 50 g of acid for every kilogram of load.

Pour ¹⁄₄ (60 g) of citric acid (190 g acid per 5 kg load) into the powder tray directly into the drum. Run the wash at the highest temperature.

2. How to clean scale with table vinegar

• Suitable for glass and ceramic teapots, stainless steel teapots, irons and washing machines.
• Proportions: teapots - 100 ml for each liter of water; irons - 1 tablespoon per liter of water; washing machines - 10 ml per kilogram of load.
• A plus: more aggressive acidic environment removes even a thick layer of scale.
• Minuses: May harm rubber and plastic parts of appliances, pungent odor.

How to clean the kettle from scale

To clean the kettle, dilute vinegar in water and put on fire. After boiling, let it simmer for a few more minutes. Then drain the water, remove the remaining plaque with a sponge and cleaning agent and boil clean water in the kettle.

Pour warm solution vinegar into the water tank and, holding the iron horizontally, release the steam.

Only boil a kettle of vinegar and release steam from an iron in a well-ventilated area.

How to descale a washing machine

AT washing machine Vinegar (10 ml per kilogram load) pour into a flask for conditioner or liquid powder. Run a wash without laundry at the highest temperature, and then another rinse to make sure you get rid of the specific odor.

Vinegar can damage the rubber bands on the door, so be careful if you decide to pour the substance directly into the drum. This can be done when there are no tanks for liquids in the machine.

3. How to clean scale with soda

• Suitable for any kettles, coffee machines.
• Proportions: kettles and coffee machines - 1 tablespoon for every 500 ml of water.
• pros: accessibility, simplicity.
• Minuses: does not take all types of plaque, does not cope with old deposits.

The mechanism for cleaning kettles and coffee makers with soda is simple: fill them with water, add soda and boil. At the same time, it is recommended not to remove the usual kettle from the fire for another 20–30 minutes after boiling, and the electric kettle to be turned on several times.

After the procedure, wash the inside of the kettle or coffee machine tank and boil clean water.

If the plaque is very strong, try a more alkaline soda ash instead of baking soda. Or add the same amount of salt to ordinary soda.

4. How to clean scale with soda

• Suitable for any kettles, coffee machines, irons.
• Proportions: Vessels are about ¾ full.
• A plus: effective even with thick deposits.
• Minus: A colored drink may stain the vessel. Therefore, for cleaning irons and white plastic electric kettles, it is better to take clear soda, including mineral water.

How to descale a kettle or coffee machine

Open the bottle and wait until most carbon dioxide disappear.

Pour soda into a teapot or coffee maker tank, hold for 15-20 minutes, and then boil.

Thanks to phosphoric acid and carbon dioxide, sodas do an excellent job with salt deposits.

Pour soda into the water tank, turn on the appliance, hold the iron upright and release steam. If there is a lot of scale, do this several times.

5. How to clean scale with brine

• Suitable for any kettles.
• Proportions: the kettle must be filled to ¾.
• pros: simplicity, accessibility.
• Minuses: does not cope with persistent plaque, specific smell.

The brine contains lactic and acetic acids. Fill the kettle with strained cucumber or tomato pickle, boil for 20-30 minutes.

After that, drain the brine with scale and wash the kettle with a soft sponge and detergent.

6. How to clean scale with soda, citric acid and vinegar

• Suitable for any kettles.
• Proportions: 1 tablespoon of baking soda, 1 tablespoon of citric acid and a glass of vinegar per liter of water.
• A plus: breaks even stone salt deposits.
• Minus: troublesome, strong smell, impact on devices of aggressive components.

Fill the kettle with water, add citric acid and boil. If the kettle is electric, do this 2-3 times. If normal, let the soda-lemon solution simmer for 20-30 minutes.

Drain and refill the kettle with water. Boil it and pour in the vinegar. Leave on for 15-20 minutes.

If after that the scale does not come off by itself, it will become loose. You can easily remove it with a sponge and dishwashing detergent.

At the end, boil clean water in the kettle again, and then drain it.

What to do to prevent scale

1. Try to pour only filtered water into kettles, coffee machines and irons.
2. Rinse the device before filling with water.
3. Do not leave water in the appliance after use. It is better to pour a new one every time.
4. Get rid of scale at least once a month, even if there is no pronounced plaque on the heating elements and walls. If the device has a self-cleaning function, use it.