Why does the cross on the human body turn black: reasons

The most unusual, mysterious and magical properties have long been attributed to silver products. Nowadays, almost everyone has silver jewelry, be it a ring, earrings, chain or cross. Many of those who wear a silver pectoral cross complain about its darkening. Let's look at the reasons for such a mysterious blackening of this precious metal.

What can increase the oxidation of silver?

The functioning of the sweat and sebaceous glands depends on many factors, but a person begins to sweat heavily due to stress or during active physical activity.
If you go to the gym or exercise at home, and you have a silver cross and a silver chain around your neck, then you shouldn’t be surprised that they have changed color. With increased sweating, the concentration of sulfates increases, which means the silver darkens more quickly.

Therefore, if you want to wear silver jewelry on your body and at the same time have to do difficult physical work or exercise regularly, be prepared to clean it regularly. How? We will tell you further.

What else influences this process? Air humidity! If you wore a chain and a cross on your chest in rainy weather or did not take them off in the sauna, then this is the reason why the silver changed its color.

Interestingly, over time, the same sweat can cause silver items to bleach, since in addition to sulfates, it also contains nitrates - salts of nitric acid.

By reacting with them, silver sulfide (dark coating on products) can be destroyed. Thus, silver on a person’s ears or body can again change color, only this time in the opposite direction - from dark to light.

https://www.youtube.com/watch?v=sJ5y1n4_JCs

These are not all the reasons why silver jewelry can turn black when worn on the body. The silver standard plays an important role: the higher it is, the less susceptible products made from this metal are to changing color, and vice versa.

Jewelry made from pure silver without impurities is practically not made, since it is very soft and can lose its shape. In order to make crosses, earrings and other items more durable, other metals are added to silver, including copper.

When copper in a silver item interacts with sulfur salts (in contact with sweat on the skin or in air rich in hydrogen sulfide), copper sulfide is formed on its surface. It, like silver sulfide, also looks like a black coating.

Evil eye, damage, unrepentant sins

Some people associate the darkening of the cross with inducing the evil eye or damage. Others believe that the owner of the blackened silver item has committed a grave sin.

When putting on a cross, remember that it is not a magical talisman or amulet that will automatically protect the owner from evil forces without the participation of the person himself. You should not believe in church superstitions and old woman’s gossip; they distract from prayer and interfere with the fight against sins.

Private opinion: Father Vladimir Golovin believes that any issue must be approached with understanding. And the blackening of the cross is associated with spiritual reasons, but not for everyone.

If your pectoral cross is broken, blackened or lost, and your conscience convicts you of some sin, then go to confession.

“Simply wearing a pectoral cross is not everything. We must visit the temple of God, confess, take communion, live the life of an Orthodox Christian, then God will protect us from all evil,” says priest Dionisy Svechnikov.

Reasons for darkening of a silver cross

Folk superstitions

From time immemorial it was believed that since the pectoral cross turned black, it meant that the person had been jinxed. It was necessary to perform a special ritual to get rid of the evil eye - light 3 candles in three different churches, and then change your cross to another.

Scientific point of view

To answer the question of why the silver cross turned black, science has found a logical explanation: silver is a metal, and metal tends to oxidize.

A silver cross, coming into contact with a person’s chest, on which there is a huge number of sebaceous glands, and the air, enters into a chemical reaction, as a result of which these mysterious darkening appears.

It is copper, in contact with sulfur, which is part of water, air, decorative cosmetics and sweat, that can be oxidized, as a result of which a black crust appears.

But everything is not as simple as it seems.

Blackening of the pectoral cross can also signal a person’s illness.

If the cross has darkened due to increased sweating, this is a signal from your body. Typically, darkening of silver crosses is the result of unstable activity of the endocrine system. The thyroid gland, adrenal glands, pancreas - some of these organs require urgent medical intervention. The functioning of the kidneys and liver may also be impaired.

Pregnant women who wear a silver cross on their body also experience blackening of this decoration. This is due to hormonal changes in the body, and in this case the silver turns black very quickly - within a few days.

There are also cases when not the entire cross turns black, but only one side of it. Let's say it turned black only on the outside.

This is explained by the fact that the outer side is more embossed and ribbed than the inner side, which is why it is more susceptible to oxidation, since the smooth inner side of the cross comes into contact with the clothing, and because of this, the access of air and sulfur to it is limited.

How to clean a cross from blackening

If the cross does turn black, it needs to be cleaned. To clean a silver cross, you don’t need any expensive or hard-to-find products; all you need is alcohol, soda, hydrogen peroxide, ammonia, citric acid or toothpaste.

If the cross has darkened, then dip it in a mixture of alcohol and hydrogen peroxide for 30 minutes, and then simply wipe with a napkin.
Cleaning a cross in foil. A very effective folk method. The silver cross needs to be wrapped in foil, placed in water and brought to a boil. As soon as the water boils, you need to add 1 teaspoon of soda. In 5 minutes the cross will be as good as new.
We take a tablespoon of soda, add a few drops of water to it to make a paste, and begin to rub it into the cross - in a couple of moments it will acquire a long-lost shine.
Mix ammonia, toothpaste and soda in equal proportions, mix everything thoroughly and apply to the pectoral cross, rub with your finger. And your cross sparkles again.
The famous Coca-Cola is also suitable for cleaning. Just soak your cross in it overnight and wipe it off with a cloth in the morning.
Boil the silver cross in a solution of citric acid for 20 minutes.

A jewelry store may offer you a special liquid for cleaning precious metals. All you have to do is immerse the silver in there for a couple of minutes, and it’s like new again.

If your cross does not turn black, but turns green, it means it contains a large amount of copper, and for cleaning you will need a special solution of Trilon B. This substance will instantly dissolve the green layer.

To prevent your silver jewelry from losing its appearance, you should not overuse mechanical cleaning - this leaves small scratches on the surface of the product.

The second method of cleaning blackened silver is “Chemical”

To do this, you just need to go to the nearest jewelry store and ask for a silver cleaner. The cost of such a product depends entirely on the size of your wallet.

But none of the above methods will help you lighten blackened silver. Believe me, this is a completely different case about which we wrote a separate article called “Blackened Silver”

If you believe in omens and think that the reason is damage or the evil eye, superstitious people advise going to church, confessing, taking communion, and praying more. If you feel unwell, we strongly recommend that you be examined by a doctor and begin treatment. A darkened silver ring, earrings or cross and chain just need to be cleaned.

The simplest and safest thing is to go to a jewelry workshop for this. Also today there are products on sale that are specifically designed for cleaning silver products at home. They can be bought in jewelry stores and in stores that sell household chemicals.

Or use one of the traditional methods, for example, clean a silver ring or chain with a solution of ammonia (0.5 liters of water - 1 tablespoon of alcohol), soda or tooth powder.

Please note that not all silver jewelry can be cleaned with the compounds listed above! For example, rhodium plated silver items (and most of them are on sale today) from the methods listed above (ready-made composition, soda, powder and ammonia) with a high degree of probability can lose their appearance and become unsuitable for wearing. Silver items with stones can be cleaned in a similar way.

We advise you to study the Morning Prayers of Optina Hermitage

If they are heavily soiled, you can pre-soak them for half an hour in warm water, adding a little laundry soap to it.

Silver items with stones can be cleaned in the same way. If they are heavily soiled, you can pre-soak them for half an hour in warm water, adding a little laundry soap to it.

After cleaning, try to properly care for your silver items so that they do not darken again!

Reasons for appearance

It should be noted that pure gold is an absolutely hypoallergenic metal. This fact is also associated with the lack of methods for specific treatment of allergies to this metal. If an allergic reaction appeared, at first glance, specifically to gold, then, in fact, the body “responded” to the effects of nickel, which is used to give strength to gold jewelry.

White gold jewelry is a combination of two metals – gold and nickel. The latter is an analogue of palladium and can often cause a powerful allergic reaction. An allergy to yellow gold jewelry can occur precisely because there is very little gold in the product.

The diagnosis of “gold allergy” is made very rarely, because the symptoms attributed to it - skin itching, irritation, redness - can also be caused by other allergens (for example, food).

An allergic reaction to silver is a fairly new and little-studied phenomenon. Previously, this metal was considered purely healing. Silver has bactericidal properties and can be used to treat many different diseases. An allergic reaction can occur as a result of wearing jewelry. The reason for this, as in the case of gold, is the presence of various impurities of other metals. This type of allergy does not require treatment - you just need to replace the silver item with a better one.

So, there is no such thing as an allergy to precious metals. The main reason for an allergic reaction when wearing silver and gold jewelry is the presence of impurities of other metals (nickel, zinc, copper).

The mechanism for the occurrence of an allergic reaction is as follows: as a result of prolonged contact between the skin and metal, ions of the latter penetrate through the epidermis into the blood and have a chemical effect on the composition of the blood. The body perceives these substances as foreign and “responds” to them by producing specific antibodies.

The occurrence of an allergy to metal is also influenced by individual intolerance to certain chemicals, upon contact with which a local allergic skin reaction may occur.

Reasons why silver darkens

Some people mistakenly associate changes in the color of silver items with the manifestation of specific diseases. People with a penchant for mysticism even assume that this signals the evil eye or damage to a person. And if the decoration darkens, it means that it took the blow.

In general, silver has long been given an occult meaning - protection from various kinds of unclean spirits and creatures. Just remember the silver bullets against werewolves. The material was used to create amulets for homes and people - crosses on the neck, anchors for those traveling by sea, a month to prevent nightmares and sleep problems, bells to cleanse rooms from evil forces, etc.

Although this effect of silver has not been proven by science, this metal does play a role in maintaining health. Silver preparations have antibacterial and wound-healing effects. The latter can be easily checked if you cover a small wound with an adhesive plaster containing silver ions. Intravenous preparations containing this metal are used for joint diseases and inflammation of the respiratory system. For some digestive problems, medications with silver as one of the components are taken orally.

But in this case, the important thing is that all mystical theories about the darkening of silver are actually just a figment of fantasy. The reasons for black deposits on metal are completely different

Sweating.

Silver is a metal that, like other substances, is subject to chemical reactions. And human skin on the neck and in other places where jewelry is worn regularly secretes sweat in greater or lesser quantities, which also contains chemicals containing sulfur. And when sulfur and silver combine, silver sulfide is formed, which has a dark gray or black color. The sulfide layer is initially invisible, then it thickens and compacts, turning into a coating visible to the naked eye.

Sweating is a natural process of the human body. But if at some point the jewelry darkens especially actively throughout the body or in a certain area, this may not only be the result of increased physical activity or heat outside, but also one of the symptoms of health problems that should not be ignored.

Impurities.

Silver itself is a very soft metal, therefore, in order for products made from it to retain their shape during use, pure silver is not used. Although an alloy is used, where about 5-8% are other metals that give the jewelry strength, even a fairly massive silver item can be bent or broken with manual effort. The metals for the alloy may include copper, and its property is to oxidize upon contact with air.

Sometimes a piece of jewelry pleases with its shine for a very long time, and then suddenly begins to turn black. This can happen if it was covered with a protective rhodium film, which has deteriorated over time. But when a purchased chain darkens too much and too quickly after purchase, we can conclude that it is of low quality, low silver content and a large number of impurities.

Other reasons.

Of the places where jewelry is worn, the largest number of sebaceous glands are located in the neck and chest. That is why most often it is chains and crosses that darken. The composition of skin secretions may change due to hormonal disruptions or changes (for example, during pregnancy). In such cases, jewelry sometimes darkens in just a few days. The color of silver is also affected by changes in the acid-base balance of the skin.

An unexpectedly strong brightening of silver jewelry may indicate problems with the kidneys or liver, because in this case, nitrogen is released through sweat, which gives the silver shine.

In general, you shouldn’t attach too much significance to the change in color of silver jewelry, much less any magical significance, but it can still be a reason to take a closer look at your overall physical condition and health.

If the jewelry was not worn, but lay in a nightstand or box, then the reason that it darkens may be dampness or contact with sulfur-containing objects or substances. Of course, silver can also change color when it comes into contact with various chemicals and some foods.

Health problems

Most often, crosses turn black in people with excessive sweating. From the course of chemistry and biology it is known that many chemical compounds are released with sweat, which, when reacting with silver, cause its darkening.

There is an opinion that the cross darkens when a person is sick. It is not without meaning. If blackening occurs suddenly, you should think about going to the doctor.

Factors influencing the increase in the degree of aggressiveness of sweat:

Stressful situation.
Taking medications, especially iodine, including externally.
Metabolic disease.
Intense physical activity.
Increased body temperature.
Problems with the liver and kidneys.
Pregnancy (hormonal changes).
Eating plenty of eggs, fish and legumes.

What Science Says

Despite popular superstitions, modern science provides a completely logical explanation of the reasons why silver turns black. Since it is a metal, it can oxidize. This is a common chemical reaction that occurs when it interacts with the environment. For example, when the climate changes to a more humid one, with frequent contact of the product with water.

There are other known reasons for the appearance of blackness on silver jewelry. This is an interaction with sulfur-containing substances. For example, when using an ointment that contains sulfur. In addition, the metal can also interact with sulfur vapor contained in the air. This is especially true for residents of industrial areas where the environmental situation is not at its best.

Environment

For people living in areas with a humid climate, especially on the sea coast, blackening of the pectoral cross is common. Hydrogen sulfide quickly oxidizes silver.

In addition, water and air pollution has reached unprecedented levels. Drinking water is disinfected with chlorine, industrial enterprises produce huge amounts of sulfur compounds.

Advice: If, after swimming in a local pond, the pectoral cross turns black or there is a chemical production facility near your house and there is a smell of hydrogen sulfide, then it is better to change your place of residence.

Scientific point of view

To answer the question of why the silver cross turned black, science has found a logical explanation: silver is a metal, and metal tends to oxidize. A silver cross, coming into contact with a person’s chest, on which there is a huge number of sebaceous glands, and the air, enters into a chemical reaction, as a result of which these mysterious darkening appears. This can also include climate change, increased air humidity or frequent contact with water. As you know, jewelry silver is, and the higher the silver standard, the less copper it contains, and the less susceptible this silver product is to oxidation. It is copper, in contact with sulfur, which is part of water, air, decorative cosmetics and sweat, that can be oxidized, as a result of which a black crust appears.

We advise you to study the Prayers to St. Roman the Sweet Singer

But everything is not as simple as it seems.

If the cross has darkened due to increased sweating, this is a signal from your body. Usually this is the result of unstable activity of the endocrine system. The thyroid gland, adrenal glands, pancreas - some of these organs require urgent medical intervention. The functioning of the kidneys and liver may also be impaired.

There are also cases when not the entire cross turns black, but only one side of it. Let's say it turned black only on the outside. This is explained by the fact that the outer side is more embossed and ribbed than the inner side, which is why it is more susceptible to oxidation, since the smooth inner side of the cross comes into contact with the clothing, and because of this, the access of air and sulfur to it is limited.

Climate

A pendant made of copper and silver quickly turns black under certain climatic conditions: high humidity near the sea, the presence of hydrogen sulfide in the air.

Chlorine content in drinking water can also cause color changes. Copper and silver ions oxidize, reacting with sulfur and chlorine compounds, which causes darkening of the metal.

If you have taken a swim in a pond and the cross suddenly turns black, it means that the water contains harmful impurities. When a liquid evaporates, chemically active sulfur and chlorine compounds enter the air.

Rain in such a climate zone will also contain substances that contribute to the blackening of the metal. Often harmful impurities in water bodies and sediments have an adverse effect on the human body. Perhaps, in the presence of aggressive climatic conditions, it is worth thinking about changing your place of residence.

HOW TO CHOOSE THE CORRECT SILVER CROSS.

Silver crosses can be divided into both men's and women's, as well as crosses for children.

When buying a silver cross, first of all, you must decide whether you will wear it as a decoration or as a symbol of faith. Remember that when buying a cross in jewelry stores, you must take into account that their assortment includes a huge number of all kinds of crosses, often very far from the Orthodox and generally Christian canons.

That is why, when purchasing a cross as a symbol of faith, pay attention to its appearance and shape. Orthodox pectoral cross, can be either four-six or eight-pointed, most often with a crucifix on the front side

On the back of the cross are engraved the words of the prayer “Save and Preserve”

An Orthodox pectoral cross can be either four-six or eight-pointed, most often with a crucifix on the front side. On the reverse side of the cross, the words of the prayer “Save and Preserve” are engraved.

Of course, when buying a pectoral cross solely as decoration, you can move away from these parameters.

Whatever cross you choose, you should not buy a product that has too sharp ends, especially if you are purchasing the product for a child. Because you can get hurt on such a cross, and wearing it will be extremely uncomfortable.

While men most often wear massive crosses, women prefer more graceful and miniature ones. In general, there are no noticeable differences between male and female crosses. The only selection criterion is your taste and income level.

However, if women prefer more expensive crosses, often decorated with precious stones, then a man will most likely prefer to get by with a simple cross, without all sorts of frills

The pectoral cross is darkening

Very often the cross turns black as a result of damage and the evil eye. Sometimes the cross turns black, and many associate this phenomenon with the presence of damage or the evil eye. Likewise, the crosses “consecrated” in this false church remain unconsecrated.

The pectoral cross is not only a symbol of faith, but also a strong amulet. If the cross is made of silver, then its blackening may mean a decline in energy reserves, a weakening of the human biofield.

If a gold cross has turned black, then in this case this phenomenon will have a completely different explanation. If we turn to the scientific explanation of this phenomenon, it turns out that the cross can turn black as a result of oxidation.

Causes of blackened crosses

Gold or silver oxidizes only upon contact with water, as well as with increased sweating of a person wearing a cross. My husband’s cross has turned black (my husband is baptized). And after some time, my husband’s nephew was baptized, and two days later his cross also turned black.

Unfortunately, you did not tell me the material (metal) from which the crosses were made. A silver cross can turn black due to a hidden illness of the person wearing it.

So the fact that your cross has darkened is a natural process, there is nothing wrong with it, the cross can be cleaned.

So why did a silver chain, for example, or earrings turn black, and how to deal with it? Of the places where jewelry is worn, the largest number of sebaceous glands are located in the neck and chest.

That is why most often it is chains and crosses that darken. We all wear silver crosses. Silver also darkens in other diseases. No. The eldest son and husband have absolutely brilliant crosses. Been wearing it for a long time. I have an old cross.

Silver always darkens when it feels something is wrong with the wearer’s health.

But you never know, maybe in other crosses there is a slightly larger proportion of other metals - so they don’t darken. As for the cross, I think it’s from contact with some substance (cream, lotion, you never know what else) So don’t worry!!! I found this thread because I have something to say. I wore a ring, a chain and a silver cross (light silver) for two months or even more without a break.

But there are some nuances here too. And even from a scientific point of view, very often a blackened cross is a sign of health problems, and therefore a sign of a weakened biofield. If you don’t do this and wear it in the same condition, then along with it you will carry a load of negative energy, which will attract failures and illnesses to you.

How and with what to clean?

As a rule, evil spirits settle in houses whose owners are involved in the occult, spiritualism, card fortune-telling, extrasensory perception, etc. Quote from the book) But besides this, they also consider this theory to be close to the Orthodox faith.

Our debates are heated. Silver oxidizes and darkens over time.

That is, the Church is for fruitful cooperation with psychology and psychotherapy, subject to adequate delimitation of methods of influence and areas of competence in accordance with the situation of each person.

There is no place for God in her concept of forgiveness. A person forgives everything to himself. This is a hidden education of pride and exaltation over others. I have time and funds for pilgrimage trips.

Are there parasites living in your body?

It seems to me that in this matter it is possible and necessary to choose the path of the “golden mean”. If you have the means to help the church and your neighbors, the desire to help is very good.

This is a matter of personal choice and has no religious significance. Therefore, do not be embarrassed, there is no sin in the fact that your salary will be transferred to a plastic card, and it will not harm your soul. Hello. I have committed a great sin. So big that for about a year now I haven’t been able to muster up the courage to go to confession, although I have a great desire to do this and take communion.

If you believe the signs, then the blackened pectoral cross must be cleaned and consecrated again. There is a popular superstition according to which, if the cross turns black, then a negative impact has been exerted on the person. So if the cross turns black, it can mean illness, depression and internal problems.

We advise you to study the Prayers to Saint Spyridon, Bishop of Trimifunt, wonderworker

How to dispel a negative interpretation

If the baby’s cross turns black, the following manipulations must be done:

go to church with your child;
ask the priest for a blessing;
buy an icon of the Mother of God and place it by the crib;
bathe the baby in holy water.

To prevent the cross from darkening anymore, it is advised:

remove it before taking a bath;
do not wear jewelry before going to the gym or sauna;
cover the decoration with white rhodium.

In any case, you need to conduct introspection and stop being afraid of troubles.

GENERAL RECOMMENDATIONS FOR THE CORRECT SELECTION OF SILVER CHAIN

Crosses and chains, both silver and gold, are an integral part of every Christian believer, and many others who do not associate themselves with religion in any way often use crosses as decoration.

Silver chains and crosses can be either modest and small or luxurious, encrusted with precious stones.

Silver chains differ in overall length, methods of weaving and connecting links, weight, and shape.

The most common chain length for men is 45-50 cm, while for women they are usually slightly longer than 50-55 cm. When choosing a silver chain for yourself or as a gift to a loved one, you need to take into account such a factor as the structure of the neck. So, for women with a short neck, longer chains are best suited, while for the owner of a “swan” neck, it is better to choose a short collar chain.

When choosing a chain, it is worth considering the weight of the decoration, since the higher it is, the more voluminous the product will look.

When choosing a silver chain for a man, you should proceed from other criteria. For a young man, a chain of medium thickness and length, with anchor, bismarck or armored weaving, is best suited. You can also consider the option of combined weaving.

We invite you to read: I made a love spell on 2 candles, what next?

Middle-aged men prefer wider, more massive chains, which in the best way emphasize their status as an accomplished, self-confident person.

Regardless of whether the chain is for men or women, you should pay attention to some decoration parameters. Do not choose a chain that has a fastener that is too small

It is better if it is slightly larger than the chain itself. You shouldn't have any difficulty opening and closing the lock.

You should not choose a chain that has a fastener that is too small. It is better if it is slightly larger than the chain itself. You should not experience any difficulty opening and closing the lock.

Silver items, such as jewelry chains, are considered a classic and very popular option. Traditional or the latest technologies in the manufacture of silver jewelry make it possible to create unimaginable models and implement intricate and unusual design solutions. Haven't you decided yet how to successfully combine your cross with a chain? Then the following tips will be useful to you.

Color Compatibility

Make sure that the two products match each other in color, this is the key to good taste. Length. Ideally, it should be 2 sizes larger than the neck size

The approximate length of the men's chain is 50 cm. Weight. Keep in mind that the cross should not weigh more than the chain. It’s good if its weight is half the weight of the chain, so it won’t pull it too much. Lock. Check its reliability and strength carefully. Weaving. Flexibility, elasticity and strength are the main criteria for weaving. The simpler it is, the faster and better the chains are repaired.

If the crosses are quite heavy, it is better to choose hand-woven rather than machine-woven chains. Machine weaving cannot always boast of reliability. Hand-woven chains are highly durable and almost impossible to break. At the same time, the chain does not lose its elegance and does not look too heavy.

Features of cleaning silver jewelry with stones

Jewelry with a stone always looks beautiful and solid.

But it also requires self-care. Especially in places where stones are attached. The stones themselves have different structures, densities and colors.

The silver on these pieces almost always has a patina, a darkening that gives it an antique appearance.

No commercial products will work. Those for silver cannot be used to clean stones and vice versa.

An enterprising seller may offer to buy two products. It would be interesting to see how he would clean the lace and swirls around a stone or the stone inside an openwork design.

The choice remains between the workshop and your own hands.

If you decide to do it yourself, then:

Be sure to select a brush for processing inlays and their fastenings.
In the same jewelry stores or pharmacies that sell laboratory supplies.

If you have aquamarine, sapphire or emerald, you can also use a toothbrush. These are high density stones. For turquoise, moonstone, malachite or opal you need to look for something softer.

Taking into account the density of the stone, you need to choose the composition of the soap solution.
For denser stones, you can use washing powder or hair shampoo; for stones of lower density, use laundry soap;

Soak your jewelry for one hour in warm water with your chosen detergent. Add hot water carefully to maintain temperature. Don't boil stones.
Handle the product carefully, but without force.
Rinse thoroughly, especially in the places where the inserts are attached.
Wipe dry. If necessary, blow with a hairdryer.

Remember, stones only look beautiful when they are well polished.

The smallest damage to the top layer, invisible to the human eye, will deprive the decoration of its main value - beauty.

Recommendations for caring for a pectoral cross

Tips to help maintain the attractiveness of silver jewelry:

It is not recommended to take a shower, play sports, or apply cosmetics without removing the pectoral cross;
every month it is necessary to clean the product from dirt using a soap solution, leave the decoration for 1 hour, after which you can rinse it;
As complex contaminants appear, including blackness, more complex cleaning methods are used.