Detailed Description of Mercury Gilding - Source wikipedia
Fire-gilding or Wash-gilding is a process by which an amalgam of gold is applied to metallic surfaces, the mercury being subsequently volatilized, leaving a film of gold or an amalgam containing 13 to 16% mercury. In the preparation of the amalgam, the gold must first be reduced to thin plates or grains, which are heated red-hot, and thrown into previously heated mercury, until it begins to smoke. When the mixture is stirred with an iron rod, the gold is totally absorbed. The proportion of mercury to gold is generally six or eight to one. When the amalgam is cold, it is squeezed through chamois leather to separate the superfluous mercury; the gold, with about twice its weight of mercury, remains behind, forming a yellowish silvery mass with the consistency of butter.

When the metal to be gilded is wrought or chased, it ought to be covered with mercury before the amalgam is applied, that this may be more easily spread; but when the surface of the metal is plain, the amalgam may be applied to it directly. When no such preparation is applied, the surface to be gilded is simply bitten and cleaned with nitric acid. A deposit of mercury is obtained on a metallic surface by means of quicksilver water, a solution of mercury(II) nitrate, the nitric acid attacking the metal to which it is applied, thus leaving a film of free metallic mercury.

The amalgam being equally spread over the prepared surface of the metal, the mercury is then sublimed by a heat just sufficient for that purpose; for, if it is too great, part of the gold may be driven off, or it may run together and leave some of the surface of the metal bare. When the mercury has evaporated, which is known by the surface having entirely become of a dull yellow color, the metal must undergo other operations, by which the fine gold color is given to it. First, the gilded surface is rubbed with a scratch brush of brass wire, until its surface is smooth.

It is then covered with gilding wax, and again exposed to fire until the wax is burnt off. Gilding wax is composed of beeswax mixed with some of the following substances: red ochre, verdigris, copper scales, alum, vitriol, and borax. By this operation the color of the gilding is heightened, and the effect seems to be produced by a perfect dissipation of some mercury remaining after the former operation. The gilt surface is then covered over with potassium nitrate, alum or other salts, ground together, and mixed into a paste with water or weak ammonia. The piece of metal thus covered is exposed to heat, and then quenched in water.

By this method, its color is further improved and brought nearer to that of gold, probably by removing any particles of copper that may have been on the gilt surface. This process, when skillfully carried out, produces gilding of great solidity and beauty, but owing to the exposure of the workmen to mercurial fumes, it is very unhealthy. There is also much loss of mercury to the atmosphere, which brings extremely serious environmental concerns as well.

This method of gilding metallic objects was formerly widespread but fell into disuse as the dangers of mercury toxicity became known. Since fire-gilding requires that the mercury be volatilized to drive off the mercury and leave the gold behind on the surface, it is extremely dangerous. Breathing the fumes generated by this process can quickly result in serious health problems, such as neurological damage and endocrine disorders since inhalation is a very efficient route for mercuric compounds to enter the body. This process has generally been supplanted by the electroplating of gold over a nickel substrate, which is more economical and less dangerous.

Fire Gold Plating In Nepal

Process of loss wax system
The lost-wax process offers exceptional quality control and customization, making it a preferred choice for artists seeking intricate and personalized metal artwork. Despite the availability of newer methods, the traditional lost-wax technique continues to be valued for its historical significance and the craftsmanship it embodies.

The method of metal casting in which molten metal is poured into a mold that has been created by means of a wax model. Once the mold is made, the wax model is melted and drained away. Bronze statues come to life differently than marble statues. Instead of carving a block or marble, the bronze artist uses the lost-wax technique to make a series of molds and then pours melted bronze into the final mold to create the sculpture. This method has been around since 4500 BCE.

There are a few important steps in the lost wax casting process:
Step 1: Sculpting ( It all starts in the studio with an idea, Then figuring out how to realize the vision in clay.)
Step 2: Mold Making.
Step 3: Wax Pouring.
Step 5: Wax Spring.
Step 6: Shell Dipping.
Step 7: Bronze Pouring.

Interestingly enough Loss wax process is also called Investment casting because after layers have been formed and dried, the wax is melted out of the ceramic tree by using steam (120°C) in an autoclave. This is why it is called "lost wax casting". The majority of the molten wax can then be regenerated and reusable.

Before Making statue :At work room making the wax models.	Softening a piece of wax over a brazier.	Relaxing after softening the wax The working environment with works in progress.
Working the face of an Ekajata wax model.	Working the face of wax model.Using a modeling tool to form the face of Ekajata.	Deatail of wax model
The design for Ekajata compared to the Tibetan book on which it was based.Statues Maker Are master in buddhism .	Detail of A partially finished Candamaharoshana (Acala) wax figure made in the Tibetan style.	A finished wax image of Mahakala.
Anthor Finished Wax Model of Shakyamuni Buddha	One of the modelers working in the room shows the Pehar image on which he is working.	The artist showed how the goat , which had been completed earlier, fits under the image. ,
Tej Jyoti Shakya and his wife, Nani Maya Shakya Covering the wax model in a mixture of clay and dung	Pressing the mixture of clay and dung around the wax image.	The board with the clay and dung mixture ready for use.
Model Pieces drying after the initial (dipped) thin layer of fine clay.	Clay-covered model pieces drying in the sun.	Molds waiting to be put into the burnout furnace
The same molds, seen in the previous image, in the burnout furnace	The double row of refractory bricks used to support the heated molds during casting.	The melting furnace and a pile of coke used for melting the metals. Laying the bed of coke in the melting furnace.
The first ignition of the coke.	Checking the coke bed.	The electric blower used to force air into the melting furnace
Beginning to fill the crucibles with scrap copper.	Preparing the bed of burning coke to receive the crucibles	Sorting various metals used in the alloys.
Weighing precious metals that are used in the alloys	Weighing copper from Singapore to achieve a correct alloy.	Different sizes of crucibles and various types of metals to be cast in this melt.
Placing the crucibles in the bed of coke filled with metal are in place.	After the crucibles are in place, more coke is piled around them.	The crucibles are covered with scrap metal to hold in the heat.
The electric fan is then connected.Soon a very hot flame is produced.	The entire furnace temperature goes up to about 1800 -1900 degrees.	Setting up molds in between the refractory bricks to receive the molten metal. Handling the molds with asbestos gloves and bracing them with fragments of bricks.
Pouring the molten metal into the base of a mold	Another view of the artists pouring the molten metal.Detailed view showing the molten metal being poured into the sprues.	Preparing to lift and pour molten metal from one of the larger crucibles.
Cooling a mold containing the recently poured metal.	Beginning to break away the clay mold from the metal casting. The mold breaks away revealing the metal image inside	The first metal image from the day's work.
Examining the image for flaws	Two auras (prabhamandalas), one that cast perfectly and one (in front) that only partially filled.	Opening more molds
Researchers mark specific metal images for future identification.	Cleaning the details of the image with a metal tool.	Sawing off the sprues from Aura image. The sprue metal will be reused in future castings.
Two auras that worked perfectly. The one on the right has been cut off of the sprues, while the one on the left still has the sprues attached.	The finishing specialist begins the finishing process with a set of tools, including a small hammer. to give more detail	The entire surface of the image will be gently hammered to a final, almost polished finish.
The finisher's tools and the work in progress	Finishing work on an image of the Buddha.	Hammering the chest of an image that is being held against the work block
A Buddha image hammered and chased to the final, detailed finish.	Cleaning in a very mild acid bath. The image and prabhamandala are placed in a final acidic bath to make sure the surface is absolutely clean.	Drying the image with a blow torch.