White metal looks attractive, which is especially evident when compared with yellow and gray. It is impossible to achieve this effect when making jewelry from pure silver. The color of the products will always be different from white. To improve external qualities, a method is used that involves creating a coating from another metal. This is silver rhodium plating. This method makes it possible to improve jewelry in a number of ways: increase hardness, increase resistance to mechanical damage, etc. As a result, the demand for such products increases many times over.
What is rhodium plating of silver jewelry and what is the rhodium used to coat silver?
Rhodium plating is a way to improve the properties of metals that are not attractive or hard. A thin film is created on the product - a protective coating. The metal used is rhodium. It is expensive (several times more expensive than gold), and therefore is not used in the production of jewelry. Their cost will be unreasonably high. For this reason, rhodium is most often used to create the plating layer. It represents the platinum group metals: Rh, atomic number – 45 (belongs to the 9th group of elements).
Note: Rhodium is used to coat jewelry, since it is distinguished by a high reflectivity of electromagnetic rays, representing the visible part of the spectrum (reflects up to 80% of radiation).
Rings with protective rhodium plating
Solution
Rhodium plating on silver jewelry is a fairly common way to prevent premature wear. This procedure is often used by jewelers around the world not only to increase the wear resistance of jewelry, but also to give the product a platinum shine and a noble appearance.
The procedure itself is nothing more than sputtering a thin (0.1-25 microns thick) layer of rhodium onto the silver product itself. The cost of this process is already included in the final purchase price. Rhodium is a rare metal whose price is much higher than the price of platinum. It has a higher level of resistance to corrosion and mechanical wear than other precious metals. Rhodium belongs to the group of noble metals due to its spectacular appearance and high chemical resistance. It retains a cold shine for a long time, which cannot be said about silver, and due to its high hardness it wears out much more slowly. Rhodium is a very hard gray metal with a noble silvery tint, which also has a very high level of reflectivity. It is precisely because of these qualities that this metal has not escaped the attention of jewelry manufacturers.
Rhodium plating on silver gives jewelry additional strength and shine, and also greatly prolongs its beauty.
Unique properties of silver. Causes of darkening of silver
The main reason for the appearance of black plaque is metal oxidation. This is a consequence of the interaction of the master alloy in the Ag alloy with substances from the environment. Indirect and direct reasons for changes in the color of jewelry:
- hormonal changes;
- playing sports;
- interaction with chemicals included in detergents and cosmetics;
- high humidity.
Silver is often used in the production of jewelry. Pure metal and an alloy based on it exhibits the following properties:
- reflectivity - determines the possibility of reflecting electromagnetic radiation incident on the surface; for silver this ability is higher than for rhodium (95-97%);
- softness: in this parameter, Ag is second only to gold; thanks to its softness, the scope of application of the metal has significantly expanded;
- plasticity: silver is used to produce thin wire and sheets of minimal thickness - this is a unique property due to which products of different shapes and parameters are created;
- density: 10.5 g/cm3, which may mean the metal is superior to iron and copper, but silver is inferior to gold and lead in this characteristic;
- color change: over time, Ag acquires a more pronounced yellow tint, but most often the metal reacts with other substances in an oxygen-containing environment, turns black, this is a natural process, it can be stopped by eliminating the alloy from the composition, eliminating all negative factors affecting the product.
Silver coin - darkening
Properties and functions of protective metal
When studying rhodium-plated silver, it becomes possible to learn more about it, for example, to understand what purposes a protective coating is applied for:
- improvement of decorative qualities;
- reduction in the consumption of gold, platinum, and other precious metals, since in part silver products can be used instead of them - more affordable, but no less attractive;
- prevention of deformation of the main product, since silver is soft;
- preservation of the properties of jewelry under the influence of other external factors.
The main feature of rhodium is its high hardness. With its help, a white coating is created, and the products do not lose this shade for a long period. Other characteristics of rhodium:
- silver-gray color;
- resistance to corrosive environments;
- loss of properties upon contact with acids; otherwise, rhodium exhibits chemical stability.
Purpose of the rhodium plating process
Rhodium is a noble metal belonging to the platinum group and occupying position 45 in the periodic table of chemical elements.
The high cost of the metal, which is 10 times more expensive than gold, is due to its content in the earth's crust. Its mass fraction is 1*10–7%. It is noteworthy that the main reserves of this element, about 43%, lie in Mexican gold deposits.
On an industrial scale, rhodium is obtained by processing native platinum. It is completely resistant to acids. Its only drawback is its fragility, which is why it is used exclusively for coating various surfaces.
The procedure in question is extremely popular due to the properties that precious jewelry acquires:
- Strength. It differs depending on the type of base material. In some cases, resistance to mechanical damage can be increased by 15%.
- Inertia. Resistance to external influences protects the base metal from aggressive substances.
- Hypoallergenic. There will be no allergic reactions upon contact with skin.
- Visual options. The rhodium-plated layer improves the appearance of things. At the same time, silver does not darken over time.
- Heat resistance. Provides additional protection against high temperatures.
Method of application to silver items
The well-known rhodium plated silver is produced by the galvanic method. This means that the precious metal (in this case, rhodium) is deposited on the base material (silver) in an electrolyte environment. This technology ensures sufficient adhesion of the coating. In addition, the durability of the jewelry increases, which is especially important, since silver is soft.
If you are wondering what rhodium plated silver is, you can compare it with other technologies. This method is significantly different from others, which also help create a coating. For example, you can compare it to anodized metal. This method is anodic oxidation.
In this case, the metal is coated with an oxide film. In comparison, oxidized products do not have a smooth surface. Rhodium plated decorations are smooth.
If you study the properties of silver, it turns out that rhodium can be used even at home. For this purpose, a special solution is purchased. You should look for it in jewelry stores. This is a solution of rhodium sulfate. The main stages of coating jewelry at home:
- Silver with rhodium is polished.
- Clean from metal dust, contaminants, and degrease.
- Place the decoration in a bath of solution.
- Pass electric current.
The product is rhodium-plated provided that the solution has been heated to +50°C and the voltage between the anode and cathode does not exceed 5 V.
The rhodium plating process involves applying a protective coating of rhodium.
Receiving technology
Rare rhodium is mined from native platinum, including in Russia (and also in Colombia, Canada and South Africa, where almost 80% of all deposits are located).
Raw platinum is placed in cauldrons, treated with aqua regia and heated for 24 hours. This produces a solution from which, through a few more chemical manipulations, rhodium is obtained - a metal resistant to both acids and alkalis, durable, but very fragile. Therefore, rhodium is not used as the main material for the production of any products. But as a coating that will protect and secure jewelry, rhodium is perfect.
The rhodium plating process is quite simple. The craftsmen use the galvanic method, but before this the product is properly cleaned and degreased. The essence of the method is that an auxiliary object acts as an anode, and the workpiece acts as a cathode. And then, under the influence of electric current, rhodium settles on the surface. The resulting layer is so thin that it is absolutely impossible to recognize.
Protective silver coating for wide applications: pros and cons
When worn, silver jewelry loses its attractiveness. The need to use precious metal to improve external qualities is due to the fact that this metal darkens. The reason is the introduction of copper into the alloy composition. The most common cause is the interaction of jewelry with human sweat containing sulfur. As a result, the products turn black.
Pros and cons of rhodium plated silver:
Advantages of rhodium plated silver:
attractiveness - products acquire a noble color: clean, cold, white;
resistance to mechanical damage;
safety for health, because the metal is hypoallergenic;
resistance to most chemical environments;
bright shine.
This material also has disadvantages:
coating is not resistant to abrasives;
Before carrying out repairs, rhodium-plated silver is cleaned of its coating, polished, and after all work is completed, a layer of metal must be reapplied;
With use, the protective layer becomes thinner.
Types of rhodium plating
Rhodium plating is used to achieve several purposes: the formation of a hard wear-resistant layer, the elimination of blackness in silver jewelry that occurs during the oxidation of silver, giving the product shine, and decorating inserts made of precious stones.
Standard
With standard rhodium plating, jewelry acquires a silver color with a cool, bright shine. Due to its hardness, rhodium perfectly protects soft precious metals from minor damage and scratches, preventing wear. The product remains attractive for a long time and looks new.
Rhodium plating is used to achieve several purposes: the formation of a hard wear-resistant layer, the elimination of blackness in silver jewelry that occurs during the oxidation of silver, giving the product shine, and decorating inserts made of precious stones.
Black
Black rhodium plating, while maintaining its protective benefits, can give the decoration the noble blackness of an expensive antique item. The coating can range from pale gray to jet black. Such items inlaid with black pearls or black stones look amazing.
The effect is achieved by changing the chemical composition used in the rhodium plating of gold, as a result of which a layer of black rhodium oxide is formed on the surface of the product.
Features of the use and care of rhodium on jewelry
Considering that rhodium is not permanently applied and can cover the jewelry for a limited period, it is important to ensure careful care of it.
How to care for rhodium-plated silver at home
Basic recommendations:
- rhodium-plated silver should not come into contact with cosmetics or alcohol;
- Do not wash dishes without removing decorations;
- Rhodium-plated rings and chains should not be worn while playing sports;
- It is necessary to frequently wash silver items under water; if necessary, use a lint-free cloth to polish them.
Important! Do not use ammonia or a toothbrush when caring for rhodium-plated products.
Rhodium plated silver ring
Tips for cleaning rhodium plated items with stones
You need to take care of jewelry containing inserts (organic, synthetic) even more carefully. Adviсe:
- do not use abrasive substances or products, otherwise the stones will become cloudy;
- In order for rhodium plated silver chains or rings to acquire the shine that they had immediately upon purchase, most often it is enough to use a soap solution, soak a cotton pad or rag in it, and clean the product.
How does coating affect the cost of metal?
Ag belongs to metals of a lower price category than platinum and gold. However, its prestige, appearance and properties increase after the use of rhodium. In addition, this precious metal is expensive, and therefore the presence of a small part of it on simple jewelry allows you to transfer silver jewelry to a higher price category.
Expensive collections of famous jewelry houses
Rhodium allows you to make jewelry “richer.” But this is only an appearance; under the coating there is still the same Ag, so in most cases the cost of products of this type does not increase too much. Rhodium-plated silver is even used by fashion houses that produce jewelry, including Tiffany, Christian Dior, Gucci. This material goes best with topaz, ruby, turquoise, and amethyst.
Tiffany earrings
Current cost of rhodium-plated silver per 1 g
The unofficial name for the metal with a protective layer is chrome-plated silver, as it has a characteristic shine and pure white color. You can purchase high-quality jewelry in specialized stores of large retail chains; this is a guarantee of the quality of the rhodium layer that covers the jewelry. Metal cost:
| Price of silver 999 (Central Bank rate), rub. | Market value, rub. | Price of metal for scrap, rub. | Cost in jewelry stores, rub. |
| 60 | 56 | 50 | 63 |
Graph of price changes (rubles) for 1 g of rhodium-plated silver (925 sterling silver) over the past months:
Birth at home
If there is a need to carry out the process of rhodium plating silver products, you must first answer several questions: 1) how much are you willing to spend to purchase the necessary reagents and devices for carrying out the galvanic deposition procedure; 2) how many times do you plan to carry out similar procedures. If only once or twice, then it would be more rational to contact specialists in a jewelry workshop.
But if you plan to put the process on stream, get ready for expensive purchases. To do this, you will need to purchase a galvanic bath and an expensive platinum anode, although many jewelers make do with a less expensive titanium anode coated with a layer of platinum - the so-called platinized titanium.
Next, you will need a working electrolyte - a solution of rhodium salt, which is diluted with distilled water to a concentration of 2 g/l. Particular attention should be paid to the cleanliness of the preparation of solutions and galvanization, otherwise it will be difficult or even impossible to obtain a high-quality result.
The process of sputtering rhodium onto a silver surface itself is quite simple, but it will require you to have some knowledge of chemistry from a high school course.
Category: question-answer
Is there radiated silver and how does it differ from rhodium-plated silver?
Expert opinion
Andrey Seleznev
Chemist-technologist, Volgograd
Radiant silver does not exist in nature. This is an erroneous user query in search engines, often asked when searching the Internet for information about rhodium plating. Radium is a radioactive metal, quite rare and expensive. It is not used for decorating jewelry, which cannot be said about rhodium. This is also a metal, but not dangerous to human health.
What is the difference between rhodium plated silver and regular silver, besides strength?
Expert opinion
Pribrezhny Gennady Valentinovich
Jeweler 6th category
Silver products coated with precious metal are protected from mechanical damage. This is a hypoallergenic material. In addition, the rhodium layer imparts a bright shine to silver, which is unusual for pure Ag, and the chemical resistance of this coating is also noted.
How to check the authenticity of silver under a layer of rhodium?
Expert opinion
Grishanov Mikhail Petrovich
Jeweler, director of the Grishanov and Co. workshop
If there is a rhodium coating, the usual method (sulfur ointment) will not give results - there will be no reaction upon application. Likewise, another reagent (iodine) does not react with this metal. To check whether an item is silver, you can obtain an approximate density value using a practical method. To do this, you need to find out the weight and volume (use the method with a liquid in which the product is immersed).
Which silver is better, rhodium-plated or regular?
Expert opinion
Pribrezhny Gennady Valentinovich
Jeweler 6th category
If you consider that under the protective layer of rhodium there is still the same Ag, then it cannot be said that some of the jewelry is better. In both cases, the same type of precious metal is used. However, products that are plated with rhodium last longer. Ordinary silver without this coating has no protection, and jewelry quickly loses its attractiveness.
Rhodium plating of silver jewelry
Silver oxidation or rhodium plating – which is better?
Expert opinion
Andrey Seleznev
Chemist-technologist, Volgograd
Oxidation allows you to change the color of the metal to a darker one. The result is the same effect as with black rhodium plating of silver. It is not advisable to compare this phenomenon with a white coating applied, since the scope of application for products of these types is different. Blackening is used to highlight the engraving, and rhodium plating is used to create a smooth finish that is uniform over the entire area of the jewelry.
Advantages and disadvantages
Much has already been said about the advantages of rhodium: strength, wear resistance, resistance to acids and alkalis, and bright shine. But what about the downsides?
But there are shortcomings, like everything. For example, when repairing a product by soldering, the rhodium coating may crack. And in general, with any repair you will have to re-spray. With intensive use, the rhodium coating wears off faster and jewelry with rhodium cannot be cleaned with any abrasives.
This, perhaps, is all the disadvantages. And the advantages of rhodium plating clearly outweigh.
Jeweler's comment
Molokanov N.M.
Jeweler, 26 years of experience in jewelry production.
Even if the rhodium plating wears off and darker silver shows through, the item does not need to be thrown away. The precious metal layer is easily restored. You just need to contact a specialist - a jewelry repair specialist. You can do all the work at home, but in this case there is no way to control the thickness of the layer: if the value of this parameter is significant, the precious metal will begin to peel off; when there is too little rhodium, silver will appear.
