Silver care

Under Silver Care refers to the removal of the black layer on silver objects . This "tarnishing" is based on the formation of silver sulfide from the reaction of the silver with atmospheric oxygen and the traces of hydrogen sulfide :

${\displaystyle \mathrm {4Ag+2H_{2}S+O_{2}\longrightarrow 2Ag_{2}S+2H_{2}O} }$

Methods

Mechanical cleaning

Silver cleaning cloths are soaked with substances that are suitable for removing the black layer. When cleaning with a silver cleaning cloth, the covering is removed by a chemical reaction with the silver cleaning agent; a black film forms on the cloth. With each use, some silver is removed. A microfiber cloth can also be used for cleaning; it has a similar effect. It should be noted that a little silver is always removed during mechanical cleaning. This is not a problem with solid silver or a silver alloy. With silver-plated objects, the thin silver layer can wear off over time.

Methods of mechanical cleaning

To mechanically clean silver, u. a. following methods to choose from

• Silver cleaning cloth
• special silver cleaning agents such as foam or pastes
• toothpaste
• Ultrasonic cleaner

Electrochemical cleaning

By wrapping the object to be cleaned in aluminum foil and placing it in a solution of water and table salt , soda or citric acid , the silver sulfide coating is electrochemically reduced to silver again. This is done according to the formula:

${\displaystyle \mathrm {3Ag_{2}S+2Al+6H_{2}O\longrightarrow 6Ag+2Al(OH)_{3}+3H_{2}S} }$

Aluminum salt method

Electrochemical cleaning is also possible with household remedies. The silver is wrapped in aluminum foil or placed in a warm saline solution (3 tablespoons of salt in 1 liter of water) together with aluminum foil. Care must be taken that silver and aluminum touch each other. During the chemical reaction, sulfur compounds are released and a rotten egg smell is noticeable.

Silver dip

Commercially available immersion baths contain thiourea , which attacks the poorly soluble silver sulfide, complexes the silver ions and forms hydrogen sulfide.

Correct storage

Silver oxidizes in the air, creating the typical black patina. It reacts strongly with sulfur, which is also found in small proportions in the air. If you want to prevent this process, you have to store silver as far as possible in the absence of air and remove the sulfur compounds from the air.

Silver cutlery should be used regularly. Frequent use and washing removes the deposits continuously. Other silver objects or silver cutlery that is not in use should be kept in a closed container if possible. A piece of chalk ensures dry air. Special tarnish protection plates are also available. They absorb the sulfur compounds from the air and thus ensure that the silver does not tarnish. If a closed container is not possible, covering it or wrapping it with a cloth can reduce air contact.

Web links

• Prof. Blume: How does the cleaning of tarnished silver work? (with recipes)

1. ↑ Cleaning silver cutlery - the best insider tips! In: cutlery box cutlery set. Retrieved on April 6, 2020 (German).