Air and reaction with sulfur
The blackening of silver like the appearance of rust on iron. Corrosion occurs as the result of the oxidation, because oxygen in the air reacts with the top layer of iron. But silver doesn't rust. It dims due to formed it of plaque. This dull layer appears when the particles of sulphur in the atmosphere, come into contact with silver.
In the Earth's atmosphere is present in the sulphuric gas, which becomes sulfur dioxide pollution of the environment.
Other causes of darkening of silver
Some Soaps include sulfur components. If you do not remove the silver chain while washing dishes or hands, the silver has a chance to darken.
Magnesium sulfate is sometimes contained in groundwater.
In some areas of the earth Epsom salt chemically reacts and is converted to hydrogen sulfide. Then the gas can rise out of the ground.
In some cases, the silver reacts with the skin of the person who wears it. The chemical composition of the skin of individual people does not allow them to wear silver on your body, because the reaction is very fast. As a result, the skin is painted a dark color and silver dark.
Perfumes, lotions and hairsprays will also react with silver. Metal tarnish from contact with wool, gloves, latex, skin, fat, ammonia, chlorinated water. Some kinds of food also cause a chemical reaction. The metal will change color, if you often eat onions, mayonnaise, salad dressings, eggs and salty foods.
How to prevent the blackening of silver
Sooner or later silver will darken. It is his nature. To silver longer retain the white color, it should be protected from moisture, do not wear every day, don't brush too hard.
In modern production applied rhodium, whereby the silver longer retains gloss and color. While jewelry is coated with a protective layer of rhodium or a special type of silver. While this layer will not be erased, the product will look good and will not blacken.
Silver jewelry should be stored in bags made of polyester. After wearing the silver should be washed with warm water and wipe with a clean cloth. This will slow the process of darkening. You can store your silver with chalk, which absorbs toxins.
To clean blackened silver need a special solution or cloth to clean the silver. Hoping that silver can turn white, it is clean different materials at hand. Do not use silver Polish toothpaste. Its components are too harsh for silver, and this cleaning will do more harm than good.
Advice 2: Why blackens silver
Silver is a beautiful precious metal and the most mysterious, its called the moon metal the same way as gold is the sun. Silver is often made of not only jewelry, but also talismans, amulets, utensils for the performance of rituals. This metal has many properties, one of them is the blackening, which can occur suddenly and need for the assistance of man.
Often, the owners of silver this attack is referred to the negative influence of evil forces. It is believed that the unexpected blackening of jewelry associated with building damage or disorder in the body. Although this superstitious fear is not so unfounded, there is still more down to earth explanation of this fact, and from the point of view of the laws of chemistry.
The blackening of silver causes oxidation of the metal in the interaction with sulfur. This chemical reaction creates sulphides that are chemicals grey-black color, which covers jewellery and other silverware.
Sulfur can enter the product of human sweat, water, cosmetics, and even air. This explains the fact that dark can even items that are practically not exposed to touch, for example, decorative.
Silverware, as a rule, contain not only the metal but also copper. This is because silver is very soft and easy to deformation, and the addition of copper makes the items more durable. Copper also undergoes oxidation and causes the formation of sulphides even more, which in turn leads to a darkening and silver.
It is known that from jewelry, to a lesser extent prone to darkening earrings. This is due to the absence of sweat glands in the ear lobes. Often darken chains and pendants, at least – rings, however, they may not darken due to perspiration, and from contact with various chemicals, for example when cooking or washing the dishes, cleaning the house.
The oxidation state of silver is dependent on purities: less susceptible to darkening of the product 999 (high) samples, more - 875. Cutlery, as a rule, contain more copper, so oxidize is stronger and can almost completely black, so they require systematic care.
Human sweat can not only cause blackening of the silver, but on the contrary, be the cause of his highlights. Religious-minded people associate it with the bright aura of a person, but it also has a scientific explanation: in addition to sulfur sweat contains nitrogen, high content of which reacts with the silver and causes the lightening decorations.
Clean the jewelry from a black can the usual tooth powder or paste.