Art etching, gilding, rhodium plating and other chemical techniques for decorating the surface of Jewellery

In Jewellery, many techniques are used to decorate the surface of Jewellery, used in the final stage of their manufacture. Using these techniques, they improve the appearance of Jewellery, give them the desired effects (shine, color, texture, and so on), and also enhance the “wear”.

In general, the technologies of artistic final processing of products can be subdivided into methods of “mechanical” impact (stamping on metal, engraving on metal, etc.), and “chemical” – applying various coatings or vice versa, removing part of the layer of an existing coating. One of such techniques – blackening of metals – can be found in our separate article. And now we will talk about other chemical methods of decoration – which, as it will become clear below, on an industrial scale have been modified to “electroplating”.

Artistic etching of metal Jewellery

Chemical etching is a spectacular old technique for decorating metals. In fact, this is the sum of techniques for “controlled removal of the surface layer of material from the workpiece, under the influence of specially selected chemicals” (as the network and Wikipedia “teach”). The gunsmiths of the Middle Ages were the very first “etchers”. They famously “threw the glove” (chain mail) in the face of the jewelers. By etching, gunsmiths have replaced one of the laborious processes – manual engraving – without lowering the quality bar.

An embossed or in-depth ornament, text or plot is applied by etching on any metal. Today etching is carried out both chemically and electroplated. Galvanic is simpler: the electrolyte solution does not emit harmful gases, in contrast to the chemical method. And the clarity of the pattern with galvanic etching is higher. Although, perhaps, when the process is not poisonous, the hands of the master do not tremble either. But in the Middle Ages (before Mendeleev and in the absence of most modern reagents) etching was a very laborious task. In those days, as a rule, metals were poisoned with acids such as acetic acid, wine vinegar, and things moved extremely slowly.

How to tell the difference between an etched piece of Jewellery?

In Jewellery, the etched areas are nostril in appearance and rough to the touch. The texture of the background, patterns, symbols and even texts are applied by etching. This is a durable type of decoration for the surface of metals: etching cannot be chipped, like enamel, or erased, like a film of silver oxide.

Jewellery gilding

In the old days, gilding of metals was carried out by masters in a cold, hot way (on fire) and in a liquid state. The oldest technique is cold gilding, in which a silver or bronze base was upholstered with a thin gold leaf.

Fire gilding is an Attic technique (used in antiquity). Mercury and gold were applied to the product in a thin layer and fired. The mercury evaporated and the gold was firmly bound to the base. The “death of specialists” gradually led to the idea that mercury vapor is unsafe.

Galvanization is a modern method of coating metals

Now about the relatively modern, galvanic method of decorating metals and alloys, discovered in 1865. Galvanization is the deposition of one metal on another in an electroplating bath, by precipitating it from aqueous solutions of salts – under the influence of an electric current or without it.

The notorious silver plating and gilding are proven electroplating methods. Silvering and gilding are carried out in cyanide-free baths, before covering the items with a layer of copper.

Gold-plated Jewellery “against” full-weight gold: which one to choose?

Let’s think soberly: what is less disastrous for the budget, a voluminous gold bracelet or silver in gilding? There is also a wealth of color (a combination of gold electroplating with a silver base, sometimes with niello), and quite affordable costs, in contrast to the “cosmic” prices in the case of a solid gold bracelet.

As for silvering, it must be helping out ethnic-style Jewellery manufacturers – and “cosplaying” costume Jewellery (by the way, like brass plating with copper plating). Silvering also helps the thrifty hostess to “fluff the tail”, serving tea with spectacular, but not critically valuable spoons.

Copper plating, nickel plating, Jewellery chrome plating

Copper plating is rarely used in electroplating, usually in the form of an underlayer for nickel plating, chrome plating, silver plating and gilding (for better adhesion of the coating to the product). Brass can serve as a sublayer instead of copper, but it is also used as an independent coating. Observing metal Jewellery of brown, olive, reddish shades, one can “suspect” copper or brass electroplating. This is a prefabricated bijouterie, as the placer elements are galvanized “in bulk”.

Nickel plating is used much more often – as a result of which the product has strong protection and a decent look. Nickel plating holds the strongest on copper or brass. The deposited nickel does not adhere well to steel, therefore, multilayer coatings are used, that is, the surface of the steel product is first copper-coated, and then polished and nickel-plated. Nickel plating is very decorative – this plating produces a silver color with a warm yellowish tint. Cutlery makers believe that when they sell nickel-plated or silver-plated knives and forks, they are selling “worthy of tradition”.

Chromium plating: durable and beautiful, but complex (very poor dissipation ability of the electrolyte, that is, it does not cover the depression well) type of electroplating. It gives a cold bluish-grayish tint. It is used, as a rule, in engineering.

Jewellery rhodium plating and ruthenium plating

Rhodium plated and ruthenium plated are the very last words in electroplating.

Rhodium and ruthenium are included in the platinum group of metals. Rhodium is a silver-gray metal with a very high reflectivity (over 80% for the visible part of the spectrum). Rhodium retains its luster for a long time. Due to its high hardness, it wears out more slowly than platinum and gold. The main thing is that the coating layer is dense enough. Rhodium plating is available in white, black and colored. Platinum and silver plated with white rhodium are extremely effective – they glow like a fluorescent lamp.

Ruthenium often acts as a ligature in Jewellery alloys, including Jewellery. Ruthenium gives the product a shine and an unusual graphite shade (like unfinished bluing). There is something infernal about ruthenium-plated Jewellery.

It is believed that ruthenium and rhodium plating “keep the product as good as new.” However, many jewelers (as opposed to sellers) are skeptical about this thesis. On the one hand, ruthenium is often covered with men’s Jewellery, and the stronger sex likes to “take it lightly”, letting the product go all the way. On the other hand, the manufacturer, “optimizing the process,” strives to turn the layer of rhodium or other micro coating into “ultra-micro” – that is, purely symbolic. They probably don’t do this with platinum Jewellery, but with silver – perhaps quite … Therefore, do not be surprised if your rhodium-plated wedding ring made of white gold, a year after the wedding, suddenly turned yellowish, having ceased to be combined with your favorite silver rings on other fingers.

Oxidation of silver and other metals

Increasingly, jewelers are using the oxidation technique – coating a product with an oxide film (according to Wikipedia, “the creation of an oxide film on the surface of a product as a result of a redox reaction”). The appearance of oxidized Jewellery resembles blackened Jewellery, which is sometimes used by sellers who are in no hurry to “disappoint” buyers.

How long will plating with gold, silver, rhodium and other metals last?

The thickness of the increased metal layer depends on the purpose of the product. The idea of ​​”rational” manufacturers that “the bracelet is not near-Earth equipment” leads to savings and prematurely “peeled off” Jewellery. However, parts covered with these super strong metals in space microcircuits work peacefully in orbit (with a successful launch), without being exposed to household chemicals, cosmetics and pungent sweat. And Jewellery, paid, by the way, with a lot of money, the owners are actively exploiting in a variety of conditions. That is, necklaces and chains around your neck chemically react with your skin, especially in hot weather. You can accidentally bathe or wash the dishes in the ring. Etc.

Therefore, we inform you that, for example, re-rhodium plating is carried out without problems in a number of Jewellery workshops.