Gilding is a decorative craft and one of the common words. Originally, it referred to the plating of a thin layer of gold on the surface of a utensil. Today we will introduce several gold-plating techniques.

Ⅰ Vacuum ion gold plating
The technology is a PVD method, which refers to the film preparation technology of depositing material on the plated workpiece by physical method under vacuum conditions. This technique can be used to plate real or imitation gold. Gold target magnetron sputtering technology was used for real gold, and reactive sputtering or real air ion plating was used to deposit TiTiTiNZrNZrCN for imitation gold. Compared with several other gold plating technologies, the real air ion gold plating film has stronger bonding force with the workpiece surface, higher hardness, better wear resistance and corrosion resistance, and more stable film performance. Does not produce toxic or polluting substances.

Ⅱ Chemical and electric gold plating
The advantage of chemical gold plating is that the plated part does not require electrical connection, the coating is uniform, and it is more suitable for surface mounting. The disadvantage is that the solution is difficult to maintain, and the chemical nickel used for the base needs to be cleaned regularly to wash away the nickel deposited on the surface of the tank, resulting in discontinuous production. Running costs are also high. The hardness and wear resistance of chemical gold plating are worse than that of hard gold plating, and the thickness that can be achieved is limited, which is not suitable for some surface mount welding methods. In order to make up for this shortcoming, electroless nickel palladium can also be used instead of electroless nickel gold, which is suitable for various welding methods of surface mounting.

The advantages and disadvantages of gold plating are reversed. The hardness and wear resistance of electric gold plating (hard gold) are better than that of chemical gold plating, and the solution is easy to maintain and does not require washing. It can be applied to various welding methods for surface mount. The main disadvantage is that the thickness is not uniform, and the parts that need to be electroplated require electrical connections.

According to its technological characteristics, there are two kinds of gold plating with or without cyanide and gold plating without cyanide. Cyanide bath is divided into high cyanide bath and low cyanide bath. Sulfite plating solution is widely used in cyanide-free plating solution. From the concentration of gold plating solution, the gold plating solution with water is generally acidic, its gold content is low, up to 0.4 ~ 0.5g/L, the cost of this plating solution is low, so the loss of the solution is less. The color of the gold layer obtained by the plating solution is blue gold, especially suitable for buttons, belt buckles and other hardware. The plating batch is large, the processing cost is low, and gold plating is required.

According to the role of gold plating liquid, pre-gold plating refers to the pre-gold plating in a specific gold plating liquid before gold plating, and then transferred to the normal gold plating process. Re-gilding after pre-gilding has several advantages:
1) Ensure the binding force of the gold-plated layer.
2) Reduce the possibility of anodic gold plating solution being contaminated.
3) Economical and practical, reduce costs.
4) Can improve the density of the gold layer.

The so-called pure gold plating is that the gold plating layer cannot contain other metal components. Therefore, in the process of gold plating, various metal salts should not be used as additives to achieve a certain function. However, the pure gold coating is soft, malleable and does not wear. Wear-resistant gold plating is used to increase the hardness of the gold layer. Meet the functional requirements of some electronic components, improve wear resistance. In order to obtain a coating with good wear resistance, additives such as cobalt salt and nickel salt are generally added to the acidic gold-plated solution to deposit a gold alloy coating containing some cobalt or nickel components to improve wear resistance.

The gold plating solution is divided by color. The commonly used rose gold is a gold-copper alloy containing 85% gold, which has high wear resistance and chemical stability and is not easy to change color. The plating solution is mainly composed of complexing agent, gold salt and copper salt.

Decorative gold alloys are mainly used in jewelry to obtain bright, clear and pleasing colors. Such as gold nickel alloy, gold indium alloy, gold copper alloy, gold and silver alloy. Most gold alloys are gold, such as gold, light gold, rose gold. The other color scheme is reddish, such as peach, pink, rose. Gold and silver alloys can also be plated with green light. Gold-nickel alloys and gold-silver alloys can also be obtained in partial color. Since gold is very expensive, it is impossible to do experiments to choose the color. The manual has some recipes to refer to, and the pharmacist also has products to choose from.

At present, the best gold plating quality is cyanide (potassium) gold plating, which is superior to cyanide-free gold plating in color, adhesion, wear resistance and other aspects. In recent years, with the progress of electroplating technology, gold-plating technology has made new breakthroughs. In the past, gold-plated jewelry had only one gold color. Now French, American, Japanese gold-plated jewelry has three or more colors. Colored gold plating, called tricolor gold, includes rose gold, silver white, gold, black and blue. In general, the uniform gold coating does not need to be too thick, only need to reach 2 microns. Heterogeneous gold plating should be thicker. Some countries stipulate that the gold coating of such products must reach 10 microns or more.