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Bangladesh traditional metal casting technics

Brass Metal Casting Techniques of Bangladesh

Life and Work of Bangladeshi Artisans

Meet the Brass Artisans of Bangladesh

Explore the mysteries behind Bangladesh's unique metal casting industry. Bangladesh is an amazing land filled with patterns of fascinating cultures, super friendly people, exciting scenery, and a centuries-old history of metal artistry. Bangladeshi artisans have been making beautiful metal objects for generations, using a variety of different methods.

Brass and metal casting techniques in this country specifically include.

  • The Lost-wax method
  • The clay casting method
  • The sand-casting method
  • The spoon-casting method
  • And the plate casting method

All these methods are in practice for making items ranging from ornate Hindu and Buddhist statues to simple household utensil items such as spoons and toilet pots.

Over the last four-five decades, many artisan families have left Bangladesh or have changed professions. With hard competition from cheaper items coming from India and other neighbouring countries in the region, families that had once passed on these skills to their descendants are now switching to other, less intensive forms of work. Thus, the tradition of hand-casted metal objects is gradually fading away.

We hope that future generations of Bangladesh will someday come to appreciate the time and effort into making these unique objects. If this trade is someday lost, an important part of Bangladesh’s artistic tradition will be gone forever.

life, culture, geography and history

Bangladesh Overview

Located at the southern curve of the Bay of Bengal, Bangladesh is surrounded by India to the west, northwest and east, and Myanmar to the southeast. Nowadays Bangladesh is standing as one of the most densely populated countries in the world, with a population of nearly 180 million people living within 147570 km² land area.

Two primary features characterize much of the country’s topography – the endless flat landscape that seldom rises more than a few meters altitude and an extensive network of large and small -rivers that dominate most of the country and – are of primary importance to the socio-economic life of this nation. Up to half of the land goes underwater during the monsoon for about to four months. The climate of Bangladesh is tropical and subtropical. Three primary seasons out of six are feelable throughout the year: ‘Rainy Season’ or the monsoon (June to September); the ‘Winter Season’ that extends from (October to February) and the ‘Summer or hot Season’ (March to May).

Undivided Bengals (Bangladesh and the West Bengal State of India) was considered as one of the wealthiest parts of the subcontinent until the 16th century.

Over the early periods, Bangladesh featured a series of Indian imperialism, internal combats, and struggles between Buddhism, Hinduism and Islam for dominance. A Strong Islamic weave washed over much of Northern India and Bangladesh by the end of the 12th century. During the Mogul rulers, Bengal was opened up to the world, literature and art flourished, overland trade expanded. Subsequently, the European powers, including the Portuguese, French and British, began to establish themselves in this region.

Within a span of fifty years, Bangladesh had flown the flags of three different nations – Indian (under British rule), East Pakistan and now Bangladesh. This young country Bangladesh had achieved freedom in 1971, through a nine-month liberation war with West Pakistan at a high price of 3 million martyr’s life.

During all of these changes and struggles, Bengal has always had a rich cultural heritage built upon a ground of ancient animist, Buddhist, Hindu, and Muslim roots. The metalwork, stone carving, weaving, pottery making and terracotta sculpturing have been revealed and refined throughout its history. There was a time when the metal casting industry in Bangladesh flourished. Unfortunately, this trend has significantly decreased over the past few decades.

Current Images and the reality is different

Bangladesh knows the world but maybe the world doesn't know Bangladesh

When any foreigner thinks of Bangladesh, they often recall images that they have seen of overcrowded urban slums, excessive poverty, and devastating natural disasters. Most of the international media reports seem to always focus on these particular negative aspects as if they represent the only thing that Bangladesh is all about. Without looking closely at its true beauty, does an injustice to this emerging nation that has so much more to offer. Bangladesh is a country that is lush, picturesque, filled with people who are proud, resourceful and passionate.

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Dhamrai

Bangladesh's Metal Casting Center

'Dhamrai' a small village at the outskirt of Dhaka city; is the main centre for metal casting industry in Bangladesh. This predominately Hindu village has been producing hand-made - metalware for many generations. Produced items are mainly for Bangladesh markets, and recently these items are attracting some international markets. On top of the metal casting objects, Dhamrai was once a famous place for making muslin saree (fine weaving cloth), jamdani saree and pottery items. A hard competition with modern technology is running over the ancient industries of this area, unfortunately.

Dhamrai is about 39 kilometres northwest of the capital city Dhaka, lies along the banks of the Bangshi and Kakilajani rivers. The rich history of Dhamrai can be traced back to the Pala Dynasty (800 – 1100 AD), during which period both early Buddhist and Hindu settlements flourished. Still, many Buddhist, Hindu and Islamic edifices can be found around Dhamrai that date back many hundreds of years. Inhabitants from different religions are living together at peace all over Dhamrai as well as in Bangladesh.

Dhamrai is also quite well known for Hindu festivals that are held throughout the year. Rathmela festival is one of the main among many. During the late June or early July (according to religious calendar) thousands of Hindu devotees from all over Bangladesh and India come here to celebrate Rathmela or Chariot festival. Hindu devotees carefully remove a set of goddesses from 400 years old Jashomadhav Temple and place them onto a large wooden Rath (chariot). Believers then pull the Rath to different temples throughout the area. Special pujas (worships) are performed at each stopping point. The Rath (chariot) and the deities return to their place of origin after nine days. The Pakistani Military had burned the 60-feet high Rath during the liberation war in 1971. Hindu devotees this area goes to the cremation grounds and dance throughout the night on the last night of the Bengali year (second week of April, mostly on 13th April). The Kali deity leads the group with a skull head and knife. The Durga, Kali, Saraswathi, Dewali, and Jonmasthumi pujas are also important and performed throughout this area.

The Craftsmen

Since few centuries, several types of casting techniques are in use for creating metal objects in different areas of Bangladesh. Nowadays, most of the Bangladeshi metal casting artisans are following these techniques:

  1. The Lost-wax method
  2. The clay casting method
  3. The sand casting method
  4. The spoon casting method
  5. The plate casting method.

The lost wax method in one of the prominent for its profound creativity and individual reputation, a particular sub-group of Hindus tend to dominate this trade. The artisans of this trade are from the “potter” cast and share the last name of Pal. The same group of craftsmen can be found in other casting approaches that use clay as the basis for the moulds. Another Hindu subgroup that usually works as carpenters and shares the last name of Sutradha, also involved in the metal casting industry. A mixture of both Hindu and Muslim expertise are involved and practising the sand casting, spoon-making and plate-making techniques around Dhamrai area. Regardless of religion, it can also be that the entire villages specialize in a particular casting method.

Bangladeshi metal casting industry has been more of a family enterprise, with every member being given a specific job and responsibility. Nowadays, the artisan often comes from different families of different locations and are most of the time paid a daily wage or a monthly salary. Workshop owner manages the process of acquiring the raw materials and developing the marketplaces. These managers receive orders and sale their wares to retailers or wholesalers throughout Bangladesh.

An elegant metal object may look very easy on the hand of an expert artisan, but much of what they do has hidden elements based on extensive experience. One must spend years to earn such perfecting skills. Anyone interested in learning these techniques must be an apprentice for several years before they are able to master much of the casting work on their own.

Over the last fifty years, many Bangladeshi artisan families have fled to India or switched profession to other trade. India is offering an easy citizenship policy for Bangladeshi Hindus. Therefore, many Bangladeshi artisans went to India to find a better life by practising their skills. On the other hand, the inventions of modern technology have narrow down the future of this precious metal industry, with hard competition from inexpensive aluminium and plastic products coming in from China and India in the region. As a result, the tradition of hand casted metal objects may soon be in danger. There are only five/ six persons left in Bangladesh who are capable of making “masterpiece-quality” Hindu and Buddhist figures. Most of them are located in the Dhamrai area.

If a viable market does not continue for these products, such heritage will disappear into oblivion.

Metal Used in the Casting Process

As a general rule, a variety of different metal combinations are used for metal casting in Bangladesh; two primary alloys are most often found - brass or bronze. Brass or Pittal has a yellowish colour and a combination of 60 percent copper and 40 percent zinc. Artisans prefer brass for most of the castings in Bangladesh. Because it is a soft metal than bronze and easier to work with during the finishing stages of an object to bring out the exact finer details.

Bronze or kasha has silverish in colour, which consists of 70 percent copper and 30 percent tin. Bronze is a harder alloy and easier to work during the casting process because of melting and cools.

Bronze is a quite complicated element to work at the final stage to bring out the details of a particular object. Bronze products are more expensive because the cost of tin is higher than zinc. Copper is relatively cheaper. Since tin and zinc are not readily available in Bangladeshi markets, they are mostly imported from China, Australia or Germany.

Only a few craftsmen nowadays use raw copper, zinc or tin for casting objects. Discarded brass and bronze metal objects are available in the local market; these metal pieces are combined, melted down and re-casted. The colour of casted objects in Bangladesh often varies depending upon the quality of the raw materials used.

Their original colour naturally fades and turns to a darker shade when the object gets older. The combination of the metal, cleaning process, frequency of cleaning, and the element of time can influence this change. If this process happens naturally, the resulting colour variation cannot be removed easily without excessive cleaning. Darker the shade, more expensive the object gets.

Not necessarily all brass and bronze items that have a darker colour or shade are old. Some craftsmen use various oxidizing techniques regularly to darken the colour or to bring an antique look. It is not that difficult to find out a copy product, the edges of new products would be sharp while you try to feel the objects and the old one would have very smooth features because of time, from wear from regular handling.

Old ones are worthy expensive.

Right Oven for Melting Process

An especially custom-made cylindrical shape oven is used in Dhamrai to melt the metals for casting. The size of an oven can be up to four feet tall and five feet across maximum. Walls are made of Bricks and sometimes reinforced with iron rods, and the top is open. A thick layer of special, durable mud covers both sides of the eight inches thick walls.

In order to fire-up the oven, about one to two inches thick layer of charcoals are placed to cover the bottom. After adding some red-hot coals on the coal layer, then they supply air through the front vent. Soon the fire spread through the whole charcoal layer and then a four to six inches thick coke layer is added to the oven. Nowadays, some of the factory owners use furnace oil instead of coke. The crucibles are carefully placed over the coals and the moulds over the crucibles. The moulds have to be red hot to avoid cracking during the casting process. Therefore the crucibles and moulds are heated at the same time and the same temperature. The fan keeps the air force through the bottom hole; thick and yellowish smoke comes for the first fifteen-twenty minutes. The smoke subsides after the temperature reaches a certain level. A lid is then placed on top of the oven to keep the heat inside. It takes about three hours to melt the metals in the crucibles. When the flame looks yellowish, then they start removing the mould or crucibles to begin the casting process.

Every year, about a month before the Durga Puja festival, the Hindu communities of Dhamrai area celebrate a ceremony to worship the ovens and the tools they use in the casting process. People also make an offering to the God of Artisan (Bisha Korma) to ensure that the casted item comes out of the oven without any defects.

The Unique Lost Wax Method

The ``Lost Wax Method`` is an essential technique used in Bangladesh to cast Hindu, Buddhist statues and various decorative antic style household and innovative items. This unique method is divided into four stages, namely (1) wax model creation; (2) forming the mould; (3) casting the mould; and ( 4) finishing the object. This technique can be employed to cast any number of desired items, ranging from statues to household goods such as bowls, pitchers and ceremonial lamps.

The Wax Model Creation

A mixture of 40 percent bees’ wax and 60 percent paraffin solution is used to make wax models. Paraffin is a white, water-soluble material obtained from crude petroleum. This material is also the main element in regular candle wax, costs approximately US$1 per kilogram (Kg). The bee’s wax is locally harvested throughout Bangladesh, costs around US$3-4 per kg. Bangladeshi artisan prefers bees’ wax and paraffin solution for several reasons: paraffin is cheaper than bees’ wax; paraffin allows wax models to shape easy and smoothly, and this combination is less sticky to work with.

In order to make the mixture; paraffin and bees’ wax together placed into a pot and heated until they both melts. After melting, the mixture is thoroughly stirred and then poured into a container of cold water. This process forms about an inch thick slab which can then be used to make the wax models.

The wax mixture is then placed onto a wooden board that contains a bit of oil so that the paraffin does not stick and stays softer. The wooden board then placed inside of a heated box that has tin walls on three sides and draping down apron in the front side. A powerful electric lamp (up to 800 watts) is placed about one and a half feet above the wax to keep the wax combination soft and pliable. It takes about an hour to soften the wax once the light has been turned on. It takes a bit longer time during the winter months when the temperature is much cooler.

The process of making models begins with a small quantity of this mixture (Mourn in Bangla), are removed from the slab. The wax is then roughly fashioned, hand-made pieces that will be a primary model of the desired object. Since it is very tough to sustain the integrity of wax models that exceed a certain height, therefore most of the items taller than twenty-inches are cast in pieces.

While making a wax model of a statue; different parts of the body (head, arms, legs and torso of the deity) are often made separately as individual units. This method flourishes every small and fine detail without worrying about the model falling apart in one’s hand. A small kerosene lamp is used at this step to heat up portions of the wax to help soften it. The craftsman often sits beside the heating box, which allows them a good light source and easy access to the soft wax. A specially cut small bamboo sticks a variety of knives known as Chakus, and sharpened hacksaw blades are employed to add crisp details to each wax model.

Once all the individual units of the object are completed, they are carefully assembled together to form the final wax model. The connecting points of every unit are heated using the kerosine lamp flame so that they are really welded together. The temperature inside the heating box can get very hot during the summertime, October to March is the best time to carry out the better output from this stage when the temperature is not as severe, and there is less humidity. During the summertime, the wax models are immediately placed into a cool water container to prevent them from melting. An electric fan is then used to dry, after removing them from the cool water tank.

It takes about four to six hours to make (less than six inches) one wax model. It may take up to twenty days or more to make one wax model depending on the size and ornamental decoration details. Many Bangladeshi artisans base their statue designs on famous photographs of Hindu and Buddhist works of art found in museums throughout the world.

Forming the Mould 

An actual mould is made in three different levels for casting metal statues. The mould is a hollow clay form that has been made to give a particular shape to something that will be casted using molten metal. These five basic ingredients are essential to make a mould – water, jute fibre, sand, rice husk, and clay.

The first step begins with white clay (Etel Doash Maati) or “China Clay” fine powder by repeatedly crushing it with a hammer, which is easily available from most riverbeds. A thin solution is made using the very fine clay powder and a small amount of water, and the mixture is carefully filtered through a very fine strainer to remove all particles. This solution is carefully painted onto each wax figure using a regular paintbrush. This solution has a very fine consistency that allows it to easily pick up the features of the model. The same process applied twice step by step on the wax model, between applications each layer is allowed to dry thoroughly at the room temperature to avoid prematurely melt the wax. It takes between one and two days for each layer to dry, depending upon the weather. The moulds should dry properly; otherwise, they can either break once the molten metal is poured in or important details may be lost.

At the second step, a combination of 10 percent jute fibre, 50 percent sand and 40 percent clay are mixed together with the water to create a sticky mixture known as Ash Mati. About 1-2 centimetre thick coating of this mixture is applied by hand to the outside of the model containing the two coats of ettel Doash Maati. It takes about 3-4 days to completely dry in the direct sunlight since the coating is thick enough to prevent from melting the wax model inside, and then the second coat is applied. A thin steel wire is wrapped around the entire mould to provide additional support for larger pieces.

Once the model is thoroughly dried, holes are made at the bottom part of the mould to allow thin rods of wax, referred to as nalis, to be attached to the wax base of the statue. Usually, two nails are required for smaller sculptures or pieces, and more holes may require for larger ones. These holes/ nails are essential for two reasons – for a passageway for the molten metal to be poured into the mould and to act as an outlet for air to escape at the same time. If this passage were not in the right place, pockets of air could form, damaging the integrity of the casted object.

A final coat containing 40 percent sand, 20 percent rice husk and 40 percent clay is used to cover the entire surface of the model on the third step. This coat ranges from 2 to 4 cm, bulky mould that forms at this step is known as a shaze. The shaze is then dried to prevent it from shattering during the casting stage. It can take between three to five days to dry, depending on the weather. At this final step, a small hole is made for each nail on the base of the reservoir through the clay down to the wax.

Casting the Mould 

As a general rule; brass metal is preferred for making statues in Bangladesh, while a variety of different metal combinations can be used in the casting process. Brass tends to be easier and softer to work with, and molten brass fills in the tiny spaces in the mould easily. Bronze, on the other hand, cools faster than brass, which poses complications for larger pieces. It also cracks and breaks easier during the finishing stages.

In the old days, 40 percent raw zinc and 60 percent raw copper would be melted together to make the brass. Nowadays, scrap metal is used for casting most objects. Scrap metal often includes discarded brass items such as pots, plates, pipes, door handles, and anything else that can be collected. These items are broken into smaller pieces. Old plates and bowls are heated to a red-hot state and then hit with a heavy hammer to be broken into much smaller pieces. The concentration of brass and other metals mixed together may vary; there is often a slight difference in the colour of objects in each casting session.

As a general rule, at a time about 100-120 Kgs of metal is cast. This is to recoup the investment needed to heat the large oven. To calculate the outcome from using 100 Kgs of metal; 10 Kgs of metal will be needed for every 1 Kg of wax used to make the wax models. This ratio may vary from country to country and region to region.

Crucibles, known as mashes, must be created before the casting can be initiated. Each of these mashes is made from a special type of clay that may not be available around Dhamrai area (it has to be brought in from other parts of the country). The basic vessel is made from 20 percent rice husk and 80 percent clay. This container has a rounded bottom and stands between 8 and 10 inches tall. Between 3-4 Kgs of brass or bronze is added to each one. A weighing scale is applied to ensure accuracy. The reason for this consistency in weight is to ensure that all of the metal in the various crucibles is melted at the same time.

After the metal has been added to the crucible, a lid is placed on top and sealed with wet clay, thus forming a unit that resembles a large clay “egg.” Ash is added to the top to help speed up the drying process. Between 25 and 30 mashes are used for each casting session. If both brass and bronze items are being casted in one session, the bronze crucibles will have a mark, such as a line around the centre, which helps the craftsmen to distinguish one from the other.

As soon both moulds and the crucibles are ready, they are put into the oven. Usually, the moulds are placed on the top, while the crucibles are placed on the bottom. The nails side of the moulds is facing the downwards, while they are positioned in the oven. This method allows the wax/ paraffin to be “burned out” after they melt. This is the origin of the phrase “lost wax method”. Soon after completion of arrangements inside the oven, the moulds and crucibles are heated until they are red hot. At least 1800 degrees Fahrenheit temperature is required to melt the brass or bronze for approximately two-three hours.

After the metal has melted, both the crucibles and red-hot shazes are removed from the oven by long pointed forceps known as a Sharashi. As a general rule, maximum one or two shazes are removed from the oven at the same time to avoid them cooling as the crucibles are being prepared for pouring.

Once the moulds are out of the oven, they are placed nalis-side facing upward. Soon after taking each crucible out of the oven, the liquid metal is gently swirled around inside to ensure that it is not sluggish. After using a spike to punch a small hole in the side, forceps are used to pick up the crucible so that the molten metal can be poured into moulds through one of the nalis. When the mould is filled, the molten metal can be seen coming out of each of the nalis. This process has to be done fast to ensure that the metal doesn’t become sticky or slow-moving. Immediately after the casting step, the hot metal loses its bright orange appearance within ten minutes, it solidifies and the colour changes to a dull grey.

For a successful casting step, the molten metal and the mould must be at the same temperature. Otherwise, the metal will not flow properly. To ensure that the metal within the crucibles doesn’t become sluggish over time, the contents of one that has been out of the oven for several minutes is sometimes poured into a mould that was just freshly removed. This ensures that the molten metal always flows quickly and evenly into each of the moulds.

During a typical casting session, it is very common for several pieces to come with defects. Likewise, it is also not uncommon for moulds to be opened only to find that an arm or leg or head did not receive any of the molten metal for some reason. The reason for these problems is often unknown to the craftsmen. This situation can bring a great loss to the workshop making these statues.

In one casting session, between four and six craftsmen are needed to complete the whole casting process. And these men tend not to be the same ones who create the wax models and the moulds. Instead, they are specialized in this particular casting step only.

It is fascinating to watch how all of these hot items are removed from the oven in such a skilful way that no one is burned in the process. The craftsmen’s precision, in this regard, is very impressive.

Finishing the Objects

After the moulds have come to a normal temperature (minimum 2 hours require), the metal object can be removed by chipping the shazes away. Since the casting process is time-consuming and exhausting, this step is often carried out on the following day. A small hammer and chisel (Sani in Bangla) are used to get the objects out of the mould. This step is a bit slower and takes many hours to complete for all casted items. A wire brush is also used to assist in removing small particles of sand and clay on the objects. At this point, the object has a dull, oily appearance that contains different shades of blue, pink, or green.

Once the pieces are freed from the mould, the nalis are cut off from the bottom of the object with a simple hacksaw. The entire statue is then filed using a tool known as a ratth. Any defects or deformities are recovered at this process and bring out the actual colour of the metal. The craftsmen also eliminate any excess material resulting from the casting process. In some cases, the casted items may have small defects caused by air trapped in tiny spaces in the mould. Likewise, some small pieces break off while the object is being freed from the mould. In order to repair these problems, an acetylene torch can be used to heat up a brass strip to reshape or fill in the holes. However, this process is very complicated and always doesn’t solve the problem.

After being repaired and further filed down, the statue is sanded with various grades of sandpaper. In the final step, if the statue is to remain without an artificial patina, a buffing machine is used to remove scratches and provide a bright shine to the piece. This shine will last for up to three months before it begins to fade.

In Bangladesh, few statues are sold without any false patina on the outside of the object. There are two reasons for using the chemicals and colours: to offer an “antique” appearance that often compliments the piece and to cover up small defects that occurred during the casting process. Depending on the desired look, a variety of different substances can be used to create these patinas. For example, to get a pink “copper” colour, sulfuric acid is placed on the outside of brass and then wiped off. The acid tends to leach the zinc off the surface, bringing out a copper colour. Nitric acid is applied and then burned in an oven to make an object black.

Some of the statues look so authentic with their rich patinas, and they are sometimes sold as old pieces. For an experienced eye, finding the difference between a new and an old piece is not a big problem. There are few things to look for those who have not been exposed to these items. First, if you feel the object and finds sharp edges, then the item is most likely a copy of an older piece. Older statues tend to have smooth features, which result from regular handling. Second, if you rub the piece and a small amount of the patina (colour) comes off on your fingers, it is not real – genuine patina can’t be removed without serious effort. Third, if the piece has an odour of any kind, it is probably not real. Statues that have been given a false patina or have been made within the past few years, sometimes have a slight scent. Fourth, most pieces that have been worshipped have some dirt and grime built up in the corners of the statue. Even with careful cleaning, this cannot be removed easily. For Hindu statues, reel puja powder can also be found on an older piece. Fifth, if the price of the piece is under a hundred dollars, it is most likely imitation-real antique pieces sell for many hundreds of dollars, if not more. There are few bargains left in the South Asian antique market. Finally, if the piece is not consistent with the type of objects found in Bengal (Bangladesh and West Bengal State, India), it is generally a copy. For example, if the statue genre is “South Indian,” an old version of this would most likely not be available in Bangladesh.

Following the finishing steps listed above, the objects are complete and ready for sale. Most statues made in Bangladesh are sold in the country. At present, an international market has not yet been developed.

One of the main differences between the Bangladesh statue industry and the industries of other countries is that the craftsmen are masters at copying figures from a simple photograph. Thus, they are more flexible in experimenting with different designs and presentations. If you were interested in buying a reproduction of a classic statue in a museum, not a difficult task at all. It can be, such statues have been reproduced with such accuracy; it is difficult to find the difference between the old and new piece without precise inspection.

As a final note, with each statue being made by hand, these items have both cultural and artistic value. Since the lost wax method does not allow for multiple statues to be reproduced using a single mould, each one is unique.