All about blackening gold
Blackened gold is one of the hottest trends in modern jewelry design. It is possible to achieve the original color of a precious product even at home.
What it is?
Pure gold is always has a yellow color, so any other shade is obtained only artificially.
This can be either the addition of other elements to the alloy, or the use of a complex dye.
Blackening of gold is carried out in three ways.
- The product can be rhodium-plated.
- Blackened gold is obtained when cobalt, sulfur and chromium are added to the ligature.
- Finally, the use of amorphous carbon can help.
Durable Cobalt has a silvery color with a yellow or blue tint, and chrome is painted either black or blue. Sulfur in this case, it plays the role of an additional material capable of creating connections with other elements. After enriching the master alloy with these materials, the alloy acquires not only a rich dark shade, but also greater strength.
The black gold alloy contains 75% gold, 15% cobalt and 10% chromium.
After creating an alloy and giving it the desired shape, the object is necessarily oxidized at high temperatures. It is after the final stage that the deep dark color of the metal is formed.
The process of plating jewelry with rhodium is called rhodium plating. Upon completion, the surface is covered with a protective film with the required shade. A similar effect occurs when the metal is covered with a film of amorphous carbon.
Rhodium plating is often used in the manufacture of precious jewelry, since the master is able to vary the saturation of the shade and so choose from a fairly wide palette of colors, from gray to purple.
Blackening of gold, mainly with rhodium, gives the product not only an original appearance, but also increases its durability. The metal becomes more ductile, does not oxidize and better resists the action of reagents and negative external factors.
Blackened gold can be of almost any color, from light gray to deep black. The brightest "classic" color is obtained using laser processing. The addition of chromium, cobalt or sulfur will change the color to brown or gray.
I must say that in the jewelry industry, using blackening, it is customary to create an emphasis on the most unusual part of the jewelry, or to use it to mask joints, connections and work imperfections.
Sometimes black is used simply to lengthen the life of the product, as the coating is water-repellent and resistant to rust.
In addition to the above benefits of black gold, it can be added that such a precious metal is absolutely safe for health and is hypoallergenic.
However, spectacular looking products also have a number of disadvantages. Black gold is quite expensive, but in most cases it is impossible to hand it over to a pawnshop. Scratches and other damage on the surface appear much more noticeable than on yellow or white metals. Finally, so far, such a product is rather difficult to find in jewelry stores due to the limited selection.
Technology
At home, as a rule, not a complete blackening of the decoration is carried out, but only an accentuation of the previously applied image. In this case, the process begins with the preparation of the product - it is not only washed, but immediately polished and sanded. If this is a new piece of jewelry that has just left the hands of the jeweler, then this step can be skipped. An image is created on the cleaned surface in such a way that the depth of the lines is at least 0.3 millimeters. This can be done in different ways, for example, minting, engraving or stamping a pattern.
The prepared mixture will be applied precisely on the created indentations in one of two ways: wet or dry.
In the first case powder for blackening is slightly moistened with water, after which it is applied to the entire area of the image. When the liquid evaporates, the object will need to be placed in the oven, due to which the process of melting the substance will begin. Thanks to heat treatment, the mixture will be distributed over the entire surface.
When choosing a dry method the product will first have to be treated with a special liquid, and then sprinkled with a finely chopped blackening preparation. After drying, the item is also sent to the oven for heat treatment.
In both cases, the work is completed by cleaning with a file or using the scraping method. The composition of the powder used for blackening is always combined from the main and additional components. The main ones are sulfides of copper, lead and silver, and bismuth, borax and ammonium chloride are usually referred to as additional ones.
When preparing a mixture for metal processing, it is necessary to decide on the method of blackening - whether it will be Russian, Moscow or German. When choosing the Russian method, sulfur must be added in portions to the main composition, and the mixture itself must be poured not into water, but onto a hot metal sheet. After crushing the substance and melting it with flux and sulfur, the mobile must be cooled.
The Moscow technology requires a separate preparation of mixtures of sulfur with lead, silver and copper. The working mixture is formed from all these compounds, taken in certain proportions.
Remelting, cooling and grinding are also required. Using German way lead is poured into a copper-silver alloy, after which everything is combined with sulfur powder. The resulting working mixture is cooled in water and then crushed.
Where is it applied?
The first thing that comes to mind when it comes to blackened gold is jewelry. This metal is actively used in jewelry, becoming the basis for rings, pendants, watches and other products. Very often, the material is also used to create men's accessories.
Quite often, black gold is used for industrial production - for example, to create thin foil or microwave oven parts.
In addition, its application is possible in the chemical and oil and gas industry, nanotechnology, telecommunications, space construction and other industries. Blackened metal has the advantage in welding and ground works. In mechanical engineering this material is indispensable for protecting the body from corrosion and rust.
You can watch the process of rhodium plating of gold at home in the next video.
