Silver electrolytes

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As silver electrolytes referred to various silver-containing solutions for galvanic silvering serve of surfaces.

A distinction is made between the following types of electrolyte:

• Silver electrolytes containing cyanide mainly contain potassium cyanide or silver cyanide , as well as potassium cyanide or sodium cyanide . Simple electrolytes containing cyanide lead to a matt silver coating. If you want a glossy coating, you have to work with special gloss additives or polish afterwards.
• Cyanide-free silver electrolytes work on the basis of z. B. Thiosulfato complexes of silver. With such electrolytes, glossy coatings can be deposited.

Silver with a high degree of purity is used as the anode .

Due to the special electrochemical properties of silver, there is a risk that many metals to be silvered will spontaneously (chemically) form an unusable silver layer (suds deposit) at the moment of immersion in the electrolyte. The subsequent electrolytic silver plating becomes defective or not adherent. For this reason, pre-treatment is required in many cases. There are the following options:

• When merging, the object to be silvered is briefly immersed in a mercury salt solution. A thin layer of mercury forms . There are cyanide-containing and acidic mixing solutions. Because of the toxicity, the entanglement is almost no longer used.
• Pre-nickel plating z. B. with an acidic nickel electrolyte .
• Pre-silvering with a special electrolyte and special process parameters (higher voltage, high cyanide concentration, low silver content).

Silver is not tarnish-resistant. The dark discoloration on table silver , which occurs mainly in the presence of sulfur compounds, is known. There are various options to prevent tarnishing:

• A thin layer of rhodium, usually less than 1 µm, can be electrolytically applied to the silver coating .
• Another possibility is to chromate the silver coating. The chromating of silver can be carried out chemically or electrolytically.
• You can apply an organic protective layer such as wax or lacquer.
• Immersing the silver-plated objects in a dilute copper chloride solution and applying an alternating current .