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CLOSE THIS BOOKForming Techniques for the Self-Reliant Potter (GTZ, 1991, 194 p.)
3. Main product lines and forming options
VIEW THE DOCUMENT(introduction...)
VIEW THE DOCUMENT3.1. Household ware, crockery, decorative and novelty items
VIEW THE DOCUMENT3.2. Tiles
VIEW THE DOCUMENT3.3. Refractories and miscellaneous industry support products
VIEW THE DOCUMENT3.4. Pipe
VIEW THE DOCUMENT3.5. Electrical products
VIEW THE DOCUMENT3.6. Miscellaneous products

Forming Techniques for the Self-Reliant Potter (GTZ, 1991, 194 p.)

3. Main product lines and forming options

This chapter focuses on a catalog of products, and what is required for forming them. The specific forming systems are discussed in detail in later chapters.

3.1. Household ware, crockery, decorative and novelty items

3.1.1. HAND METHODS
3.1.2. POTTER’S WHEEL
3.1.3. PRESS MOULD
3.1.4. SLIP CASTING
3.1.5. JIGGER
3.1.6. OTHER FORMING METHODS

Household ware and crockery mean approximately the same thing. These are products such as cups, plates, storage jars, teapots, bowls, lamp bases, etc. Decorative and novelty items are such things as flower vases, figurines, wall hangings and souvenirs. These products are capable of being produced in one and the same factory, as long as the forming methods are the same.

Household items are usually the easiest to produce without introducing complicated forming techniques. In most countries, there is already a tradition of ceramic household items, although they may not be glazed. From the point of view of forming, this does not present a major change in technology. The following is a list of forming methods, and some typical products that can be successfully made.

3.1.1. HAND METHODS

Hand methods refer to using slabs, coils and pieces of clay to assemble various forms, using only the hands and simple tools.

novelty items

There are few highly marketable items that can be made by these methods, but there are some successful microbusinesses that produce very small novelty items by hand, such as animals, flowers, etc. The process for animals is to make the body from a piece of clay, and then to add feet, ears, tail, etc., all by hand. The main point is to use fine detail, which makes the product attractive to the customer. These items are made at very low cost (mainly labor) and have a high profit margin. They are easy to export, being small.

3.1.2. POTTER’S WHEEL

The potter’s wheel still remains a very important production tool. It can be used for unique items, or for series of identical products. It depends on having highly-skilled “throwers” to produce quality items. Although handmade items are no longer so attractive in the local market, industrialized countries have a big demand for handmade products, and there is growing local prestige market and a tourist market for handcrafted ceramics.

Typical products are cups, containers, bowls, candlestands, lamp bases, flowerpots and novelties, as well as hundreds of other household and decorative items.

3.1.3. PRESS MOULD

Press moulding is the process of forming plastic clay by forcing it by hand into plaster, cement or wooden moulds. It is used to produce items with detailed relief decoration, or large forms that cannot be made any other way. Like all moulded products, it has the advantage of producing large numbers of identical items with low investment. In pressmoulding, several shapes are often pressed separately and then assembled into complicated sculptural forms.

Typical products are tiles with relief designs, sculpture (animals, gods), large flowerpots with relief designs, water containers, pipes, etc.

3.1.4. SLIP CASTING

Slip casting is the process of pouring liquid clay slip into plaster of parts moulds. It has the advantage of producing large quantities of identical forms, and is especially good for products that are not round (square pots, irregular shapes, etc.).

Typical products are flower vases, lamp bases, relief design tableware, figurines, etc.

3.1.5. JIGGER

This is a machine that is really a semiautomatic potter’s wheel, which uses plaster moulds to produce identical items. It is most useful for hollow ware, which means open forms (cups, bowls, plates) that have a big mouth, and is best for round shapes. This machine is frequently called a “jigger-jolly”, but for simplicity’s, in this book it will always be called “jigger”.

The jigger is the standard method for making dinner plates, soup bowls, teacups, and similar forms.

3.1.6. OTHER FOAMING METHODS

Other methods usually are combinations of the above. For example, cups produced by jigger may have handles made by slip casting.

3.2. Tiles

3.2.1. SCOPE FOR THE SMALL PRODUCER
3.2.2. HANDMADE TILES
3.2.3. PLASTIC-PRESSED TILES
3.2.4. SEMIDRY PRESSED TILES
3.2.5. GLAZED AND UNGLAZED TILE CONSIDERATIONS

Tiles refer to flat plates of clay that can be set together to cover walls and floors, or specially shaped tiles for roofing. There are many kinds of tiles, glazed and unglazed, with relief designs and plain. Tiles are popular all over the world for use in and on buildings.

3.2.1. SCOPE FOR THE SMALL PRODUCER

Nowadays, most standard glazed tiles are produced by very large-scale, automated factories, which are able to make their profit through large volume and low amount of handling. Because the industry is so large and aggressive, it is impossible for the small producer to compete directly in terms of quality and cost.

competing with big industries

However, there is also a good market for special decorative tiles, which may have relief designs or painted glaze designs. These are in great demand in industrialized countries, where they have a high profit margin. Another product is unglazed red clay tiles, which are very popular for floor and wall covering. These are best for the local market, since they normally are not transported for long distances (which increases their cost too much). They have a low profit margin, but like the brick industry, they are profitable because of large volume production. Similarly, unglazed roofing tiles are also marketed in the local area.

3.2.2. HANDMADE TILES

Handmade tiles are a good business in many countries. There are two types:

- unglazed red clay tiles, which can range from 30 cm x 30 cm x 3 cm for floors, down to about 10 cm x 10 cm x 1.5 cm.

- glazed relief design tiles, which usually range from 15 cm x 15 cm x 2 cm down to small sizes.

These tiles are made in frames or plaster of parts moulds, and require only a small investment in machinery.

3.2.3. PLASTIC-PRESSED TILES

These tiles are usually plain-surfaced, but are more uniform in size and finishing compared to handmade tiles. They are made with a press machine which uses metal dies, and the machine may be hand-operated or motorized. They use clay in the plastic state. They are relatively easy to produce, but require quite a large amount of transporting and hand finishing.

The process is most suitable for unglazed floor and wall tiles, but can also be used for glazed tiles and is the normal system for making roofing tiles.

3.2.4. SEMIDRY PRESSED TILES

These are tiles made with clay powder having a low moisture content of up to 10%, or using leather-hard clay (a variation of plastic pressing). They are usually plain-surfaced, and are faster to produce compared to plastic-pressed tiles. However, they require more control in clay preparation, and may need more investment in machinery. They use the same type of press machine as above (with higher pressure), but have the advantage of being almost dry after they are pressed. This reduces drying problems and minimizes the amount of handling and transport required.

The process is commonly used for glazed and unglazed wall and floor tiles.

3.2.5. GLAZED AND UNGLAZED TILE CONSIDERATIONS

As mentioned above, the small producer is not advised to compete directly with standard glazed tile manufacturers. It is much easier to enter into unglazed tile production, which will give better results with fewer problems. There is always a good scope for unglazed floor tile, facing brick, etc. There are many successful businesses in Thailand making unglazed relief tile for the outside of buildings. Likewise, there is good scope for unglazed roofing tile - in countries like Nepal and Burma, there is not enough good quality roofing tile to meet the demand.

relief tile

Glazed relief tile has a good scope for the small producer, and requires only investment in a few plaster of parts moulds. Even small orders can be profitable, since there can be a good profit margin added. A producer who is already making household items can consider making relief tile, without having to change any of his equipment.

3.3. Refractories and miscellaneous industry support products

3.3.1. FORMING METHODS
3.3.2. KILN FURNITURE

Refractories are all of the products that are necessary for firing ceramics. “Refractory” means “capable of withstanding high temperature”, and the refractories industry produces firebricks, insulating bricks, kiln shelves (setter slabs), etc. Additionally, ceramics factories need special items like porcelain balls and lining bricks for ball mills, and porcelain jars for pot mills. Where a substantial ceramics industry already exists, there is often enough business to support a refractories factory. If you have a fairly large ceramics industry and are purchasing expensive imported refractories, it is worth thinking about producing certain items yourself as a sideline, and possibly selling them to nearby factories as well.

Miscellaneous industry support products are pot mill jars, balls and brick linings for ball mills, mortars and pestles, chemical storage containers, etc.


FIGURE 3.3-A Examples of ceramic products: a mortar and pestle, a jar mill and lining bricks and pebbles for ball mills.

3.3.1. FORMING METHODS

Refractories can be made by simple methods, including hand-extrusion, semidry pressing, hand-moulding and casting.

3.3.2. KILN FURNITURE

Kiln furniture refers to setter slabs (kiln shelves), saggers and various stands, specialized setters for plates, tiles, etc. These are generally formed as follows:

- Extrusion: A hand extruder can be used for producing stands to support kiln shelves.

- Semidry pressing: Kiln shelves are made with semidry (about 10 % water) clay. They cannot be made in standard screw press machines, which do not have sufficient pressure. The classical and still best way to make them is in a metal frame, handbeating the clay to make it uniform and dense. Other specialized shapes, such as “thimbles” for tile setting, are made in presses. Firebricks are made either by pressing in screw presses, or, for better quality, beating clay by hand into metal moulds.

- Hand-moulding: Setters for plates can be moulded by hand on the potter’s wheel. Porcelain balls for ball mills are often made simply by rolling clay in the hands. Saggars are usually made by wrapping clay slabs around wooden forms and beating them into shape. Insulating bricks are usually “slop-moulded” in wooden forms (as is done everywhere for common bricks), and are sometimes pressed in a screw press when they have stiffened to give them a more uniform size.

- Slip casting: Ball mill jars are sometimes cast, or simply thrown on the potter’s wheel (which makes a stronger jar because it aligns the clay particles better). Setter slabs (shelves) are also sometimes cast.

For more information, see Refractories and Kilns, in this series of books.

3.4. Pipe



3.4.1. KINDS OF CERAMIC PIPE

Ceramic pipe can be glazed or unglazed, d pending on its use and required strength. There are several uses for pipe:

- Simple, low-pressure water pipe: This is usually unglazed, is used only for short distances, and can be made on the potter’s wheel or in a two-piece mould. Another system involves wrapping plastic clay slabs around a wooden form. It requires almost no investment, and is suitable for traditional (no kiln) firing systems.

- Perforated drainage pipe: This is unglazed, has holes along one side, and is used for collecting excess water under roads, or in soak pits (leach fields) for septic tanks. It can be made on the potter’s wheel, extruded, or in a two-piece mould. It has the same requirements as water pipe.

- Chimney pipe for stoves: This is unglazed, and also is made on the potter’s wheel or in a two-piece mould. It is the same as making water pipe.

- Sewage pipe: This is glazed and fired to higher temperatures, and is best made in quantity by an extruder machine. Sewage pipe is also suitable for carrying irrigation water, and is capable of withstanding relatively high pressure. It is suitable for small-scale industry, and requires high capital investment.

- Semicircular roofing tiles: These are thrown as small pipe and later cut in half. This is the usual way to make village roofing tiles, which is slowly disappearing because the roof is very heavy and requires too much wood for construction.

3.5. Electrical products

3.5.1. SEMIDRY PRESSING

Electrical products suitable for small producers are low-tension insulators and fuse holders. These are relatively easy to produce and do not require too much quality control. These products are formed by:

3.5.1. SEMIDRY PRESSING

- Fuse holders are made in small toggle presses or screw presses. These hand-operated presses require low investment. They often are made as a cottage industry, where there is one central clay supplier and firing center. The fuse holders are pressed in homes, usually by one person using one toggle press. Each morning, these workers come to the center with their finished goods and collect enough clay for the day’s production. They are paid by the piece.

- Low-tension insulators are formed in presses. They can be made according to the same system as fuse holders. They sometimes are extruded and then shaped on a potter’s wheel.

3.6. Miscellaneous products

3.6.1. WATER FILTERS
3.6.2. AGRICULTURAL ITEMS
3.6.3. SANITARY WARE

3.6.1. WATER FILTERS

With more and more education on hygiene and the need for clean drinking water, water filter units are becoming popular. The water containers can be made cheaply, on the potter’s wheel or by using plaster moulds and hand-pressing. The filter candles are more complicated, because they require a special clay body, and have to be fired to an accurate temperature. They can be formed by casting, or by pressing in a metal mould.

3.6.2. AGRICULTURAL ITEMS

Agricultural items include animal feeding containers and irrigation pipes (as mentioned above). These are usually made by hand, on the potter’s wheel, or by using simple moulds.

3.6.3. SANITARY WARE

Although the small producer should not expect to make high quality vitrified china sanitary ware, there is good scope for simple products intended for the low-cost market. These can be formed with a low investment, but, in the case of toilet pans, require a large kiln Products include:

- simple toilet pans, footrests and traps, using red or white clay, which are formed by hand in press moulds;

- large unglazed red clay rings used for lining pit toilets, which are formed in hand press moulds.


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