GB2135627A - Improvements in or relating to the manufacture of Tandoori ovens - Google Patents

Abstract

A method of making an inner lining post for a Tandoori oven includes moulding in respective moulds a pair of clay shapes (11 and 12) each corresponding to approximately half of the required pot. The clay shapes are made from a mixture of clay, water and jute fibres and are allowed to dry until they are self-supporting then removed from the moulds and heated until it has a hardness comparable to that of leather. The shapes are then assembled with their co- operating surfaces wetted and the joint is bound with a jute bandage (15). The resulting pot is finally dried using a heat source (16) introduced into the interior of the pot through a vent hole (17) previously cut in the bottom shape 12. <IMAGE>

Description

SPECIFICATION Improvements in or relating to ths manufacture of Tandoori ovens This invention relates to improvements in or relating to the manufacture of Tandoori ovens and in particular concerns a method of making an inner lining pot for such an oven.

A Tandoori oven has an outer enclosure in which is supported an inner lining pot made of clay. The inner pot of the oven takes the form of a surface of revolution about a vertical axis with a diameter which increases from an open lower end of the pot to a maximum and then decreases again to an open upper end of the pot, so that the pot has a substantially pot-bellied shape.

The inner pot is supported within the outer enclosure above a burner arrangement which may be fueled by charcoal or gas, so that hot gases pass upwardly through the inner lining pot which itself also becomes heated. In use, the temperature conditions within the inner pot are such that bread or the like may be cooked by pressing suitable dough onto the inner surface of the lining pot in its upper region, whereas pieces of other food-stuffs, such as meat, may be simultaneously cooked by piercing them with a skewer of suitable length which is introduced into the lining pot.

Conventionally, the inner lining pot for such an oven is manufactured using a rope of clay which is progressively coiled, each coil being placed on the preceding coil and having the required diameter so as to build up the required pot-shape.

The green pot is then fired, causing the individual coils to coalesce into a pot having a wall of substantially uniform thickness.

This traditional method of making an inner lining pot for a Tandoori oven is of great antiquity and produces perfectly satisfactory pots.

However, this method is excessively time consuming, both as regards preparing and coiling the clay rope and the subsequent necessary firing of the resulting clay pot.

It is an object of the present invention to provide an improved method which enables a lining pot for a Tandoori oven to be manufactured in a more economical and cost-effective manner.

Accordingly, the present invention provides a method of making an inner lining pot for a Tandoori oven, comprising moulding in respective moulds a plurality of clay shapes each corresponding to a respective portion of the pot, allowing the clay shapes to dry until the shapes are self-supporting, removing each clay shape from its mould and heating the shape until it has a hardness comparable to that of leather, assembling the plurality of clay shapes together to constitute the pot, and finally drying the resulting pot using a heat source introduced into the interior of the pot.

Conveniently, two clay shapes are moulded, each constituting approximately half of the required pot. Conveniently, each clay shape is produced by pressing a plurality of suitably dimensioned, trapezium-shaped clay laminae into the mould, so as to form a clay shell which adopts the form of the mould and in which the adjacent edges of the trapezium-shaped laminae are merged together. Suitably, the trapezium-shaped laminae are cut from a sheet of a clay mixture composed of clay mixed with natural fibres, such as jute. The sheet, which may be about one inch thick, is prepared by beating, rolling or otherwise suitably flattening the clay mixture.

In the case of a mould made of non-absorbent material, the mould surface is preferably lined with a water absorbing material (for example paper) prior to the introduction of the clay into the mould, so as to absorb excess water from the clay.

In order that the invention may be readily understood. An embodiment thereof will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic illustration of a pair of moulds for forming a lining pot of a Tandoori oven in accordance with a method embodying the invention; Figure 2 is a perspective view of a clay laminae used in the moulding method embodying the invention; Figure 3 is a perspective view of a pair of moulds shown in Figure 1 after the introduction of the clay lamina into the moulds; Figure 4 shows a pair of clay shapes being further dried after removal from the moulds; Figure 5 illustrates the assembling of the two clay shapes into a pot; and Figure 6 shows the assembled pot being finally dried.

Referring now to the drawings in detail, in one embodiment of the invention a method of making an inner lining pot for a Tandoori oven employs two half-moulds 1 and 2. The mould 1 is used to produce a first clay shape 11 corresponding to an upper half of the pot and the mould 2 is used to produce a second clay shape 1 2 corresponding to a lower half of the pot. The half-mould 1 has a circular aperture 3 in its base corresponding to the desired open top of the pot to be made.

Similarly, the half-mould 2 has a bottom opening 4 corresponding to the desired base opening in the eventual pot.

The material from which the pot is made is a mixture of clay, water and natural fibres (for example jute) which is beaten, rolled or otherwise formed into sheeting having a thickness of approximately one inch. From this sheeting there are cut trapezium-shaped laminae or pieces 5 (see Figure 2) which are dimensioned so that four such pieces, when fitted into the mould with the larger of the parallel sides of each piece uppermost, abut and cover the inside surface of the mould.

In carrying out a method embodying the invention, the moulds 1 and 2 are first lined with an absorbent sheet material 6 (such as paper) as shown in Figure 1 and the corresponding four trapezium-shaped clay pieces 5 are laid into each mould (see Figure 3), the clay pieces being pressed into the mould so as to conform to the mould surface. The joints between the individual clay pieces are smoothed whilst the clay is still in its wet condition, and the resulting clay shapes 11 and 12 are allowed to dry in the moulds for a period of from two hours to overnight until they are self-supporting and capable of retaining their form. If necessary or desired, this partial drying process may be accelerated by blowing warm air into the moulds using a fan heater or the like (not shown).

After the clay shapes 11 and 1 2 have dried to a self-suppo.rting condition, they are turned out of their respective moulds onto a suitable surface in an inverted condition and the adhering layer of absorbent material 6 is peeled off. The clay shapes 11 and 12 are then subjected to a further drying process in which they are dried until they have a hardness comparable to that of leather.

Figure 4 shows the clay shape 11 being further dried using a fan heater 7 to blow hot air into the interior of the inverted shape, while the clay shape 12 is dried by means of a heat source (in this case a gas burner 8) introduced into the interior of the inverted shape. This drying process occupies in the region of an hour.

The next step of the method involves turning the clay shape 12 constituting the bottom half of the pot the right way up and wetting the upper rim 13 of the shape 12. The other clay shape 11 is maintained in the orientation shown in Figure 4 and is lowered (Figure 5) onto the shape 1 2 which by now is sufficiently dry to support not only its own weight but aiso that of the clay shape 1 The lower rim 14 of the clay shape 11 is aligned with the upper rim 13 of the clay shape 12 and a bandage 15 of natural fibre, such as jute, is applied around the joint (see Figure 6).

The assembled pot is then subjected to a final drying process by means of a heat source (in this case a gas burner 16) introduced into the base of the assembled pot through a vent hole 17 previously cut in the lower clay shape 1 2. This final drying process conveniently continues for a period of say eight hours or overnight. At the end of the final drying process, the pot is dry enough to fire, should this be desired. However, in practice, it is preferable not to fire the lining pot prior to its installation in the outer enclosure of the oven, but instead to allow the pot to become fired progressively during subsequent use of the oven.

The above described method of making an inner lining pot for a Tandoori oven finds particular application in the case of commercial ovens requiring lining pots which have a height of twenty-eight to thirty-two inches and a diameter of from twenty-five to thirty inches. The manufacture of such pots by the conventional method of coiling a rope of clay is extremely time consuming and costly.

Claims (8)

1. A method of making an inner lining pot for a Tandoori oven, comprising moulding in respective moulds a plurality of clay shapes each corresponding to a respective portion of the pot, allowing the clay shapes to dry until the shapes are self-supporting, removing each clay shape from its mould and heating the shape until it has a hardness comparable to that of leather, assembling the plurality of clay shapes together to constitute the pot, and finally drying the resulting pot using a heat source introduced into the interior of the pot.

2. A method according to claim 1, wherein two clay shapes are moulded, each constituting approximately half of the required pot.

3. A method according to claim 1 or 2 wherein each clay shape is produced by pressing a plurality of suitably dimensioned, trapeziumshaped clay laminae into the mould, so as to form a clay shell which adopts the form of the mould and in which the adjacent edges of the trapeziumshaped laminae are merged together.

4. A method according to claim 3, wherein the trapezium-shaped laminae are cut from a sheet of a clay mixture composed of clay mixed with natural fibres, such as jute.

5. A method according to any one of the preceding claims, wherein the mould surface is lined with a water-absorbing material (for example paper) prior to the introduction of the clay into the mould so as to absorb excess water from the clay.

6. A method of making an inner lining pot for a Tandoori oven, substantially as hereinbefore described with reference to the accompanying drawings.

7. A lining pot for a Tandoori oven when made by a method according to any one of the preceding claims.

8. Any novel feature or combination of features herein described.