Gilding at home: methods of applying gilding

By learning how to do gilding at home, which is not as difficult as it might seem at first glance, you can give a second life to your favorite copper and silver jewelry. Products made from gold have been very popular among both women and men for many years. To own such products without significant costs for their acquisition, it is enough to master the technology of gilding.

Both non-ferrous alloys, steel or cast iron can be plated with gold

What metal products can be coated with gold plating?

The most common process is gilding silver, but gold plating can be applied to the surface of other metals. Thus, gilding can be applied to products made of copper, brass and zinc, as well as iron and steel, etc.

There is no clear answer to the question of how to gild metal at home. It all depends on what metal products need to be subjected to such processing. The choice of gilding technology carried out at home is also influenced by the result that needs to be achieved.

With the help of gilding you can give ordinary things a completely different look.

Various methods can be used to gild metal, the most common of which are:

rubbing the surface of the product with a solution of gold chloride;
gilding, performed by immersing the product in a solution with a zinc contact;
galvanic gilding.

Each of these methods of gilding, performed at home, requires the use of certain chemicals, tools and equipment.

How to gild metal at home

Products made of gold-plated metals have always been very popular. When handled with care, they looked beautiful and were inexpensive.

Therefore, many could afford to change jewelry often and match it to the appropriate outfits. However, over time, the gilding wore off, and gilding in a jewelry workshop costs even more than the product itself.

Therefore, many people think about how to gild metal at home.

Technology of coating objects with gold leaf

Gold coating of plastic, wood, metal and other materials is carried out using the thinnest sheets - the thickness of gold leaf (cladding) is 0.13-0.67 microns.

In the old days, gold leaf was made by hand, today special equipment is used. Depending on the thickness of the sheet, free and transfer (on silk paper) gold leaf is distinguished.

It is very difficult to work with the first one - the slightest breath interferes with the process.

The finished material is stored in little books - each of the 60 sheets is covered with paper. Applying gold leaf is a painstaking process.

The technology is based on the ability of gold rolled out from a sheet to be attracted to the surface at the molecular level.

There are two techniques for gilding with gold leaf: glue (for polyment) and oil (for Mordan varnish). In the first case, a glossy surface is obtained, and in the second, a matte surface.

The adhesive method is used when carrying out interior work.

Amalgam gilding

The amalgam (fire) gilding method is another ancient method of applying precious metal. It has a high degree of durability, but the process itself is extremely toxic and is not used today.

The essence of the method is the molecular penetration of a precious metal dissolved in mercury into the base (during the firing process, the mercury evaporates, but the gold remains).

An example of such work is the dome of St. Isaac's Cathedral in St. Petersburg.

Preparation and use of gold chloride

To gold-plate metal, a solution called gold chloride is often used. To prepare such a solution, gold is dissolved in “aqua regia,” which is a mixture of hydrochloric and nitric acids. Hydrochloric and nitric acids are taken in a ratio of 3: 1. Gold is placed in this composition, and then the liquid is evaporated. The procedure for evaporating liquid from such a solution should be carried out very carefully so as not to cause burns to the skin and respiratory tract. The dry substance remaining after evaporation is precisely gold chloride.

When evaporating, you need to separate the open fire from the container with the solution, for example, by making a layer of asbestos chips poured into a separate container

Before using gold chloride for gilding, it must be mixed with a solution of potassium cyanide and washed chalk, resulting in a paste-like mass. Using a brush, this paste is used to cover the product, after which it is left for some time, and then thoroughly washed and polished.

To gild steel, gold chloride is mixed with ether. The product coated with this composition is left for some time until the ether has completely evaporated, and then the treated surface is simply rubbed with a cloth to impart a golden shine.

Using gold chloride, previously mixed with ether, various inscriptions and patterns can be applied to a metal object. In order to carry out this procedure, a quill pen is dipped into the resulting solution and the required inscriptions and patterns are made, which, after evaporation of the ether and polishing, will sparkle with a golden sheen.

Large surfaces are covered with gold using a soft brush

As mentioned above, gold plating is often applied to silver, for which gold chloride can also be used. To perform chemical gilding of products made from this metal, it is necessary to prepare a mixture that includes the following components:

gold chloride – 10 grams;
potassium cyanide – 30 grams;
table salt – 20 grams;
soda – 20 grams;
water – 1.5 l.

Chemical gilding, which must be applied to silver, can also be performed using a mixture of:

gold chloride – 7 grams;
potassium ferric sulfide – 30 grams;
potassium carbonate – 30 grams;
table salt – 30 grams;
water – 1 l.

The procedure for sputtering a layer of gold onto a metal surface using chemical solutions is performed in the following sequence.

The product being processed is pre-calcined.
The surface of the object is etched first with a solution of sulfuric acid and then with nitric acid.
The pickled product is momentarily dipped into a mixture consisting of sulfuric, nitric and hydrochloric acids.
After treatment in a mixture of acids, the product is rinsed with water, then immersed in mercury and finally in water, where it is kept for 30 seconds.
After a container of water, the product is placed in a solution for gilding, kept for the required time, then washed with water and dried in sawdust.

Various gold plating techniques

The quality of the resulting surface largely depends on the characteristics of the technology used. The most widespread are the following:

Electroplating method: gold plating.
Use of special chemicals.
Mechanical method of applying the required substance.

In each case, certain tools and chemical reagents are used.

At the same time, some technologies are suitable for coating chains at home, others for processing other products for their intended purpose.

Chemical method

Chemical gilding of silver or other alloy is the process of applying gold chloride to the surface being treated. Recommendations for creating the required reagent are as follows:

The metal must be forged onto pre-prepared foil. All elements must be crushed into small elements.
Small pieces are immersed in a mixture of a previously prepared chemical reagent. The solution is created by combining 30 grams of hydrochloric acid concentrate and 10 grams of nitric acid. It is worth considering that you need to work with such substances at home carefully.
For one gram of spraying there is at least 10 ml of solution. That is why you should calculate the required amount of liquid in advance.

Gilding solution

Porcelain dishes are used to mix active reagents. The dissolution process can last for three days. After preliminary preparation of the metal, it is evaporated at a temperature of about 80 °C until liquid appears. At the time of evaporation, you should stir the resulting consistency with a glass rod from time to time, which will result in a homogeneous composition.

When carrying out gilding of metal, it is necessary to qualitatively prepare the required composition. To do this you will need:

Water purified from impurities at a temperature of 60 °C.
About 15 grams of gold chlorine salt syrup.
More than 65 grams of potassium carbonate or sodium chloride. Both substances must undergo high-quality purification.

The surface of silver or other items should be coated only after preparation. To do this, degreasing is carried out using 20% sodium hydroxide, after which the product is washed in a 25% soda solution.

After preparing the surface, the product is coated in the previously prepared mixture. After some time it becomes gold plated. After removing and drying the surface, it is washed and wiped with a dry cloth. To give a more attractive look, the gilding is polished with woolen cloth.

Mechanical methods of gilding

Gold plating is characterized by certain qualities that make the product more attractive and resistant to environmental influences. Mechanical application of gold plating is carried out extremely rarely, since it is quite difficult to achieve uniformity of the surface layer. The features of the technology under consideration include the following points:

For such gilding, a special paste is used. It can be prepared in a specialized store or made with your own hands. The composition of the paste may vary significantly, which is worth considering.
The layer obtained by using the mechanical method of gilding at home has a small thickness. That is why the resulting coating will not last for a long period.
Common ingredients include yellow blood salt, chalk powder and cream of tartar.
It is recommended to mix the paste with water to obtain a homogeneous paste, which is rubbed into the surface using a woolen cloth.
Before gilding at home, the surface must be degreased. Special compounds are also used for this.
The gilding paste should be applied in an even layer; when rubbing, care should be taken to ensure that the substance does not get on exposed areas of the skin.

Manual gold plating

Mechanical technology is quite complex to implement. As a rule, it is used if you need to cover only part of the product at home. This is due to the fact that other coating technologies involve complete immersion of the product in a special solution.

Gilding by electroplating

A thick layer of high quality gold plating can be obtained using special technology. It involves immersing the workpiece in a special electrolyte. The galvanic method is used to process a wide variety of workpieces, as it resembles common electrochemical processes.

It is worth considering that depending on the type of solution used, the surface can acquire a variety of shades. You can make an electrolyte for gilding yourself at home as follows:

For 700 ml of purified water, add 60 grams of sodium phosphate.
When using 2.5 grams of gold chloride, 150 ml of water is used to dissolve them.
10 grams of sodium sulfide, as well as one gram of potassium cyanide, are dissolved in 150 ml of distilled water.

Such reagents should be handled with care. Gold electroplating at home is carried out by heating the solution to a temperature of about 60 °C, and an anode is installed to activate the chemical process to deplete the electrolyte.

It takes about 15 hours to process the workpieces in such a solution. A low current helps to significantly increase the efficiency of the process. Due to this, a matte gold film is formed on the surface.

Application of zinc contact

To obtain a thicker gold-plated layer, a zinc contact is used. Using this method, you can, for example, coat silver with a layer of gold. For gilding, a composition is prepared from the following components:

gold chloride – 15 grams;
carbonic potassium salt – 65 grams;
yellow blood salt – 65 grams;
table salt – 65 grams;
water – 2 l.

It will take some time to dissolve all components of the composition

Products made of copper and brass are plated with gold in a solution of the following composition:

gold chloride – 2 grams;
caustic potassium – 6 grams;
potassium cyanide – 32 grams;
sodium phosphorus salt – 10 grams;
water – 2 l.

Objects on the surface of which it is necessary to apply a layer of gilding are thoroughly cleaned of dirt and grease, then they are placed in a preheated gilding composition. The products already there are connected to a zinc rod, which acts as a contact.

Compositions of degreasing solutions

In order for the gilding applied to the surface of products made of steel, zinc and tin to be of high quality and have good adhesion, they must be subjected to a copper plating procedure before gilding.

Chemical method

A) Chemical gilding is the process of applying gold chloride to the metal from which the product is made. Gold chloride is prepared as follows: the metal must be forged into foil and crushed into small pieces, immersed in a mixture of nitric and hydrochloric acids (in the so-called aqua regia). You need to take 30 g of concentrated hydrochloric acid and 10 g of concentrated nitric acid. For 1 g of gold there should be 10 ml of solution.

Applying gold plating at home

Dissolution must take place in a porcelain bowl; the process can last from several hours to 2-3 days. When the metal is completely dissolved, it is necessary to evaporate the mixture in a water bath at 70-80 degrees until a viscous golden liquid appears. When evaporating, the solution is stirred with a glass rod.

To prepare the mixture for gilding, you will need:

Hot purified (distilled) water (50-60 degrees) in a volume of 2 liters.
15 g of gold chlorine salt syrup.
65 g each of potassium carbonate (potash) and highly purified sodium chloride (Extra salt).

Before applying gilding, the surface of the object must be degreased with 10-20% sodium hydroxide or by boiling in a soda solution. Next, the product is washed in a 25% solution of hydrochloric acid, i.e., pickled. After degreasing, it is necessary to rinse the item in water.

Next, the product for gilding is immersed in a prepared mixture of hot water, potash, sodium chloride and gold chloride. The object is touched with a zinc rod, after some time it becomes gold-plated. After this, it is removed and washed, wiped dry and polished with woolen cloth.

B) In addition to the chemical gilding method, the rubbing method using paste is used. With this method of applying gold plating, the coating layer is thinner. The composition of the rubbing paste includes yellow blood salt (potassium hexacyanoferrate [II]), cream of tartar, chalk powder, and gold chloride. To make 100 g of paste, take 55 g of chalk, 5 g of creamtartar, 30 g of yellow potassium hexacyanoferrate and 10 g of gold chloride, and mix the ingredients. The resulting paste is diluted with water until a paste forms. Rub the fat-free product with this mixture using woolen cloth.

C) There is a third coating method. To do this, 10 g of gold is dissolved in a mixture of nitric and hydrochloric acid, water - take 25 g of all components. Add 300 g of potash (potassium carbonate) to this composition. Prepare a cauldron in which water (2 liters) is boiled, pour this mixture into it. Boiling continues for 2 hours.

Jewelry that needs gilding is calcined and etched first with sulfuric acid, then with nitric acid. The product is then wrapped with brass wire (an alloy of zinc and copper), and immersed for a moment in a mixture of nitric, sulfuric and hydrochloric acids. Then the objects are rinsed, then they are alternately loaded into mercury, and then into water. After half a minute, they are dipped into the prepared liquid, washed, and dried in hot sawdust.

Product with gold plated

1) Iron and steel.

To gild steel and iron products, you need to dissolve gold chloride syrup in ether. The resulting composition, applied to a cloth, is used to cover and rub the surface of an object made of steel or iron. Then the ether evaporates, but the gold remains.

If it is necessary not only to gild an item, but to make a pattern on it, then moisten a pen in a mixture of ether and gold chloride and rub it over the item.

It is advisable to cover the surface with copper before gilding objects made of iron, steel, tin, zinc, since gilding fits better on it.

2) Zinc items.

Coating of zinc products is carried out by rubbing them with paste. It is prepared from 60 g of potassium cyanide, 20 g of gold chloride and 100 g of water - these ingredients are mixed. 5 g of cremortartrate and 100 g of calcium carbonate powder (chalk) are added to this solution. The resulting composition is applied using a brush or brush.

To coat silver jewelry, there are two options for the solution in which objects are immersed:

10 g of gold chloride, 30 g of potassium cyanide, 20 g of soda and sodium chloride, one and a half liters of water.
7 g of gold chloride, 30 g of potash, yellow potassium hexacyanoferrate and sodium chloride, liter of water.

While immersing the product, you need to touch it with a zinc stick and it will begin to be covered with gold. After this, the object is removed from the solution, washed and wiped, and polished with a woolen rag.

Gold chloride (2 g) and potassium cyanide (32 g) are dissolved in 0.5 liters of water. Meanwhile, caustic potassium (6 g) and sodium phosphorus salt (10 g) are dissolved in another one and a half liters of water. Mix both solutions and boil.

Technical information about our gold plating capabilities

has the opportunity to offer the following types of electrolytes and coating methods in our production, as well as the sale of electrolytes, equipment and technological processes for their implementation in your production.
The following list of processes is the most extensive on the market. Thanks to him, we have the opportunity to offer gold application using all known and proven methods.

Both in baths (chemically and electrochemically) and tribogalvanically using gold-containing gels.

Immersion gold plating (no current)

Immersion gold plating is used when applying gold coating to radio components, microcircuit housings, and printed circuit boards. Immersion gilding occurs by the reaction of replacing the underlying metal with gold. As a rule, immersion gold is applied to an electrochemical nickel coating.

The coating thickness increases until all coated surfaces are covered with gold. After this, the reaction stops. In this way, it is possible to obtain 24-karat gold coatings up to 0.2 microns thick.

We have at our disposal a composition both for simple immersion gold plating and with mixed properties (first the composition works immersion, then continues to chemically apply gold, increasing the thickness.)

Chemical gold plating (no current)

Chemical application of gold coating on products of the radio-electronic industry up to 0.5 microns. It is also used for products of very complex shapes and when the same coating thickness is essential in all areas of the product. Gold purity in the coating is 9999+. Applied to chemical nickel or immersion gold to increase adhesion. Available in 2 different formulations.

Galvanic gilding under the influence of electric current

Electrolyte for applying gold (only in baths), phosphate. It is characterized by a relatively low application speed and requires heating up to 60 degrees. Thin coatings retain shine, but when thick coatings are applied, dullness occurs and accumulates. Has moderate adhesion to most metals. However, all these shortcomings are compensated by the very high purity of the applied gold plating with a purity of 9999 and a perfect golden color. Thickness up to 20 microns. The electrolyte is mainly used technically in industrial enterprises, in most cases of applying electroplating with pure gold to radio components, contacts, boards, etc. gold from 1 g/l and above at the customer’s request. Product preparation includes degreasing and activation. gold 2-100 g/l. It is possible to adjust the electrolyte for gold during operation.
Electrolyte for underlayer gilding, acidic - pH 1. Used to prevent initial contact deposition of gold at the very beginning of plating and when it is not possible to achieve proper adhesion of the gold coating immediately in the main gilding baths. There is no point in applying coatings thicker than 0.1 microns from such an electrolyte. gold 1 g/l.
Matte alkaline gilding electrolyte for baths to obtain coating thicknesses up to 100 microns. Gold plating purity 9999. Requires preliminary gilding. gold from 1 g/l to 100 g/l.
Electrolyte of weakly acidic galvanic gold plating with nickel alloying additive, the content of which in the coating is 0.1-1.5%. - at the request of the customer. The higher the nickel content, the higher the wear resistance of the coating and the more noticeable the color change towards lightening from pure gold. Compared to pure gold, the abrasion resistance of such coatings increases by 8-10 times. Thickness up to 10 microns, then the coating becomes matte. Suitable for decorative gilding of tableware, jewelry, souvenirs, costume jewelry, watches, weapons, etc. and so on. Preparation for coating products includes degreasing and activation.
Electrolyte of weakly acidic galvanic gold plating with the alloying addition of cobalt, the content of which in the coating is 0.1-1.5%. - at the request of the customer. The most common gold plating electrolyte. The higher the cobalt content, the higher the wear resistance of the coating and the more noticeable the change in color of the coating towards pinkishness from pure gold. Compared to pure gold, the abrasion resistance of such coatings increases by 8-10 times. Thickness up to 10 microns, then the coating becomes matte. Suitable for decorative gilding of tableware, jewelry, souvenirs, costume jewelry, watches, weapons, etc. and so on. Preparation for coating products includes degreasing and activation.
Electrolyte for applying gold plating under 585 standard, so-called “rose gold”. It is used to give products a tint of “Soviet” 585 gold alloy. It is possible to select a shade based on the customer's sample. The abrasion resistance of such a coating is 4 times higher than that of a gold-cobalt alloy. The plating is a ternary gold-based alloy, the actual fineness of which is approximately 750.
We have the ability to prepare gilding electrolytes according to the customer’s recipe, as well as other compositions not listed here for applying various alloys of gold with other alloys, including precious metals, for both decorative and technical purposes.
Gold-containing gel for local application of gold plating using the tribogalvanic method, as well as coating of large oversized products.
Electrolyte for applying gold locally tribogalvanically, without a gel thickener (unlike gels, it allows the gold contained in it to be deposited on products much more completely)
Various liquids and electrolytes to give the freshly applied gold plating different shades.
Electrochemical polishing of gold and its alloys. (several compositions)
Removal of gold coating without etching the surface of products, both for restoration purposes and for the purpose of metal regeneration.

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Electroplating

Common electroplating technologies have a number of disadvantages:

Harmfulness - electrolytes are cyanide or conditionally cyanide-free. (cyanide compounds evaporate and poison the air);
Expensive - high gold content in the electrolyte and professional equipment require significant financial costs;
Complexity - the gilding process is complex and requires significant experience and knowledge;
Disposal - Highly toxic used electrolytes must be disposed of. They cannot be poured down the drain or onto the ground!

Electroplating

There are two ways:

Three solutions are prepared: 60 g of sodium phosphate with 700 g of water; 2.5 g of gold chloride and 150 g of water; 1 g potassium cyanide and 10 g sodium sulfate with 150 g water. The first two solutions are mixed, the third is added last. Temperature - 50-60 degrees. The anode is made of platinum. When the electrolyte solution is depleted, gold chloride is added.
Bath according to Zelmi: mix 1 g of potassium hexacyanoferrate (yellow) and sodium carbonate with 30 g of water, heat in a porcelain cup. Add gold precipitated with ammonia to the mixture. Boil for 10-12 minutes. When water evaporates, it is added and a Daniel element current is passed through the solution. Exposure time is 15-16 hours.

Gilding methods at home are labor-intensive and not always available. The preferred method is chemical gilding or rubbing.

Source: dedpodaril.com

We prepare gilding solutions ourselves

To gild any object, you need a solution, or rather, dissolved gold. To obtain it, you need to dissolve gold in the so-called “aqua regia” - a mixture of hydrochloric and nitric acids. They must be taken in a ratio of 3:1. After the gold has dissolved, the liquid must be evaporated. This must be done very carefully, because you can get burns to your hands, face or respiratory tract. What's left is chlorine gold. It must be dissolved with a solution of potassium cyanide, and then mixed with washed chalk. You need enough of the latter to get a paste of liquid consistency. Taking a brush, you need to cover the object that you want to gild with the resulting slurry, and after a while it needs to be washed and polished.

To gild steel and iron, a solution of gold chloride is often used, which is mixed with ether. It evaporates, and the gold-plated surface must be rubbed with a cloth. You can make a gold pattern. To do this, take a quill feather, soak it in gold and draw the desired pattern or line.

Purchasing Tips

You can purchase high-quality gold-plated jewelry in jewelry stores, but you need to know some selection rules so as not to be mistaken in the value of the product.

Silver products must have a stamp confirming the hallmark . If it is not there, then it is not a precious metal, but a jewelry alloy coated with gold. Such products are often purchased because they are cheaper, but they quickly deform.

Different types of silver can be used to make jewelry, but experts recommend choosing 925 silver. Products made from it are of much higher quality, so they will last a long time. The percentage of gold plating should be more than 40%.

Chemical gilding

There are two types: the atomization method (spraying) and the immersion method (immersion gilding). They have a number of disadvantages:

Gilding by spraying is a method designed for professionals. Quite expensive and cannot be used at home. Requires protection of the gold coating with varnish;
Gilding using the immersion method (immersion gilding) is possible only on copper (brass and bronze) bases. The maximum coating thickness is 0.25 microns and, as a result, low resistance to abrasion and mechanical loads. Low durability;

Source: funchrome.ru

Electroplating method of applying gold plating

The most durable and high-quality layer of gilding allows you to obtain electroplating with gold, performed in special electrolytic solutions. This gilding technology is very similar to galvanizing, since it uses electroplating and similar electrochemical processes.

Galvanic bath diagram

Depending on the chemical composition of the solution in which galvanization is performed, the formed gold plating may have a reddish or light yellow tint. Basically, gilding of metal products using this technology is carried out in two types of solutions.

Electrolytes for gilding of the first type are prepared in the following sequence.

60 grams of sodium phosphate are dissolved in 700 milliliters of water.
2.5 grams of gold chloride are diluted in 150 milliliters of water.
In another 150 milliliters of water, dissolve 1 gram of potassium cyanide and 10 grams of sodium disulfide.
First, carefully mix the first two solutions, and then add the third to the resulting mixture.

To gild silver or any other metal using this method, the prepared composition is brought to a temperature of 50–62° and a platinum anode is used to carry out the process. After depletion of such an electrolyte for gilding, gold chloride is added to it.

Defects when using gold plating electrolytes and ways to eliminate them

The second type of electrolyte for gilding is called “Zelmi’s gold bath”. In such a solution, silver, steel, products made of tin, copper, brass, and Christophean metal are gilded. The preparation of this electrolyte for gilding occurs in several stages.

In a porcelain container, bring to a boil 30 milliliters of water, mixed with crystalline sodium carbonate and potassium ferric sulfide (taken 1 gram each).
Gold fulminate precipitated with ammonia is added to the resulting solution and boiled for twelve minutes.
After the formation of a red fluffy precipitate, the resulting liquid, which should have a rich golden color, is filtered.