Bronze Masterpiece Statues of Hindu Gods by Bronze Creative  

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The Lost Wax Method Stage 4 Casting the Mold
 

This step is the very important to the finished piece and requires a working knowledge of the casting process.  Timing and temperature are extremely important.  If the casting process is performed improperly the entire piece may be lost.

The Heating of the Mold  The mold is placed within a small igloo-type house of bricks.  A fire is lighted around it.  The fire is very hot to burn out all the wax from the interior of the mold.  During the firing you can see the wax actually burning out of the piece by a little fire at the pouring spout.  
Melting the excess wax from the earthen mold

Varun & Varadaraj inspecting the mold being fired
Once there is no longer a flame the wax has been completely melted out of the mold and the mold is ready for casting.  All the wax must be completely melted out of the mold for a safe and successful casting. 
The flame from the wax burning out of the mold

The pouring spout where the excess wax melts out

The following is how long it takes to melt the wax out of a mold;

1 hour for a 12 inch wax mold
1 hour for a 24 inch wax mold
2.5 hours for a 36 inch wax mold
4 hours for a 48 inch wax mold
8 hours for a 60 inch wax mold
10 hours for a 72 inch wax mold

A hole is dug in the ground for the mold to be placed into.  The mold is removed from the fire and placed with the pouring spouts facing upward so that the liquid bronze can easily be poured into the mold. 
Using cow dung patties to insulate his hands from the hot earthen mold

Burying the mold with the spouts facing upward

The Heating of the Metal  The metal must be heated in conjunction with the firing of the mold.

Bronze is a combination of copper, zinc, tin and small amounts of silver and gold resulting in what is called Panchaloha bronze.  The Bronze Creative has developed a heating method using propane gas for heating the metal.  Using propane allows the artist to control the exact heat of the fire.  The old method was to use large amounts of wood for extended periods of time to heat the metal.  This was bad for the surrounding trees as well as an inefficient and wasteful way to heat the metal.  However, the new method of using propane also emits carbon into the atmosphere so neither is a perfect solution.

 

The metal is heated in special clay containers called crucibles from Andra Pradesh that are four different sizes depending on the size of the statue within the mold. 
Placing the metal into the crucible

 


Weighing the metal

The weight of metal that is melted is proportionate to the weight of wax model.  For every 1 kg of wax the artist must melt 10 kg of bronze.  Thus it is important to weigh the wax mold in the first step of the process before the earth mold is made. 

The metal is heated until the metal is completely liquid.  Long iron rods are used to mix the metal and to check for liquidity. 


The tools of the firing process

 

Stirring the metal

 

Stirring the metal...again.  The process takes hours

The following is how long it takes the metal to melt while being heated;

45 kg of metal takes 2 hours to melt
60 kg of metal takes 3 hours to melt
120 kg of metal takes 4 hours to melt
750 kg of metal takes 5 hours to melt

Firing process is long.  During the process a lot of dirt and unwanted material enters the crucible.  A large spoon or ladle attached to a long iron pole is used to scoop up the excess waste on top of the liquid metal and is then discarded into an iron bowl.  Because the liquid metal is denser than the dirt the dirt is on the top of the liquid metal and is easily scooped away.  This causes a safety hazard as some metal usually is dropped on the ground.  For this reason castings are always performed at night when the molten metal is easily spotted on the ground and can be avoided. 
Using a spoon or ladle to remove excess dirt

The excess dirt is placed in a pan so no one steps on it

Once the metal is melted, the excess dirt is removed and all the wax is burned out of the earthen mold the piece is ready to be cast. 

It is very important that the metal turns to liquid and all the wax is melted from the mold at approximately the same time.  This is the correct time for casting to ensure a positive result. 

Depending on the size of the crucible being used for the casting 1, 2 or 2 people and pulley system are used for the pouring of the metal.  The crucible is picked up out of the fire and brought over the mold placed in the ground.  Moving the liquid metal is extremely dangerous.  Happily the Bronze Creative has a perfect safety record with only minor burns experienced during castings. 

Pouring the Metal  A burlap bag is added to the top of the crucible and is ignited by the heat.  The burning bag performs 2 functions for the casting process.  It acts as insulation maintaining the high heat of the top layer of the metal.  During pouring it also acts as a strainer, catching any extra waste materials that were not removed by the spoon. 

The crucible is then tilted and the liquid metal freely pours into the pouring mouth of the mold.  If all the wax was not completely melted out of the mold the mold violently regurgitates the liquid metal out of the pouring mouth making it absolutely essential that all the wax is melted out of the mold. 

The pouring is completed once the metal has completely filled the pouring mouth up to the top.   
The extremely hot metal fills the mold up the top

A finished pouring

 

 The casting process is complete and the mold is allowed to cool off.

Stage 1
Wax mold
Stage 2
Earthen mold
Stage 3
Melting wax
Stage 4
Pouring the metal
Last step, Stage 5
Finishing the bronze

 

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Packing and Shipping
  How the Statues are made.
Lost wax Method
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