FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
COMPLETE SPECIFICATION SECTION 10
TITLE
A COOKING UTENSIL.
APPLICANT
HAWKINS COOKERS LTD., AN INDIAN COMPANY OF MAKER TOWER, F--101 CUFFE PARADE, P 0 BOX 16083, MUMBAI 400 005, INDIA.
The following specification particularly describes the nature of the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION:
This invention relates to a cooking utensil. Though reference is made subsequent herein to a pressure cooker, such a reference in onfy by way of an exemplary embodiment. Thus, the present invention can be extended to any cooking utensil.
BACKGROUND OF INVENTION:
One of the disadvantages associated with the known construction of pressure cookers made of aluminum is that the cooker bottom tends to bulge-due to pressure acting thereon after a prolonged use.
In order to obviate such a disadvantage, it is known to provide pressure cookers with a substantial base thickness, but which substantially contributed to the end cost of the pressure cooker. A distinct advantage of a thicker base of the pressure cooker is that the bottom continues to remain permanently flat, and whereby such cookers could be used for cooking on electric hot plates.

However, when used on gas stoves, the cooker bottom develops scratch marks due to continuous rubbing on the cast iron pan supports of the gas stove.
In order to obviate the disadvantage of such scratch marks, it is known to provide hard anodized pressure cookers, which due to the hardness of the coating surface is scratch proof. However, to provide, an anodized coating is expensive and considerably contributes to the end cost of the pressure cooker.
OBJECTS OF THE INVENTION:
An object of this invention is to propose an improved construction of a cooking utensil and to. a method of manufacture thereof.
Another object of this invention is to propose an improved construction of a cooking utensil and to a method of manufacture thereof which obviates the aforesaid disadvantages.
Still another object of this invention is to propose an improved construction of a cooking utensil arid to a method of manufacture thereof which is scratch proof.

Yet another object of this invention is to propose an improved construction of a cooking utensil and to a method of manufacture thereof which is cheaper in costs than the fully anodized cooking utensil of the known art.
Further objects and advantages of this invention will be more apparent from the ensuing description.
DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
The invention will now be explained in greater detail with the help of the accompanying drawings wherein

Figs 1 and 2 show the utensil bodies with the hard anodized coating.
BRIEF DESCRIPTION OF THE INVENTION
According to this invention is provided a cooking utensil (1) such as a pressure cooker and wherein the bottom or base (2) and only a part of the sidewall (3) of the utensil extending from the base (2) is hard anodized, said anodized portion

(4) extending upto a height of 5 to 30 mm from the base and the anodization has a thickness of 30 to 100µ.
Further according to this invention is provided a method for the manufacture of a cooking utensil such as a pressure cooker which comprises in providing a hard anodized coating to the bottom or base and a part of the sidewall extending from the base of the cooking utensil.
In accordance with this invention and Figs 1 and 2 of the accompanying drawings, a cooking utensil (1) is provided such as a pressure cooker, with the base (2) and a part of the sidewall (3) extending upwards from the base is hard anodized (4). The extent of anodization depends on the volume of the utensil body and the anodized portion (4) generally extends upto a height of about 5 to 30 mm from the base, preferably 11 to 23 mm. The thickness ranges from 30 to 100u, preferably 50u. The hard anodization renders the anodized portion scratch proof and the utensil absorbs heat better and is resistant to bulging at the base.
Fig 1 shows a cooker body in a preferred embodiments on which the hard anodized coating extends upto 11 mm from the base and Fig 2 as shows yet

another preferred embodiment of the cooker body with the hard anodized coating
extending 23 mm from the base upwards.

It has been found that only the base or bottom of the pressure cooker which is in contact with the cast iron pan supports of the gas stove is subjected to scratch marks. Similarly, such scratch marks can also be imparted to the surface in the proximity of the base. Accordingly, in order to avoid the costs of providing a hard anodized coating on the entire surface of the utensil, satisfactory results are achieved by providing a hard anodized coating on the base and only a part of the
wall surface extending from the base. Besides the advantage of rendering the

utensil scratch proof and imparting strength properties to the base, an additional
advantage is that due to the dark colour of the hard anodized surface, the utensil
absorbs heat better than a bare aluminium copker.

In accordance with this invention, the process of the cooking utensil involves a special anodizing process using an oxidizing medium, such as for eg. sulphuric acid. The anodization is carried out in an agitated sulphuric acid bath. However, in accordance with an embodiment, a placid bath may also be used with almost the same effect. The utensil is suspended in the electrolysis bath by means of a special jig wherein the cooking utensil is clamped fully around its circumference from outside so as to ensure proper electrical contact and thereby also ensuring that the inside surface of the cooking utensil is free from any blemish. However, a disadvantage that accrues from the use of an agitated bath is the formation of undulations on the anodized body of the utensil. This is overcome by the use of a masking agent. A groove in the form of a step, designated as A in the accompanying drawings extends horizontally across the sidewall of the utensil to be anodized in a circular fashion and forms the demarcation between the anodized portion and the rest of the body of the utensil. Any masking agent, preferably a tape is used. The tape is so wound around the outer surface of the body of the utensil in such a manner that it extends upwards from the step or groove. This masking agents covers the areas of the utensil body above the groove or step, to protect it from anodization. However, seepage of the anodizing agent through passages between the making agent and the utensil body is commonly encountered. This results in anodization of portions above the

step. Such portions are cleaned by removal of the undesirable oxide coating by machining, manual removal by selective abrasive application or by any other suitable means. Thus, a horizontal sharp demarcation is developed between the anodized bottom portion and the rest of the sidewall of the cooking utensil.

WE CLAIM:
1. A cooking utensil (1) such as a pressure cooker and wherein the
bottom or base (2) and only a part of the sidewall (3) of the utensil
\ extending from the base (2) is hard anodized, said anodized portion (4) extending upto a height of 5 to 30 mm from the base and the anodization has a thickness of 30 to 100u.
2. The cooking utensii as claimed in claim 1 wherein the height of said
anodized portion (4) is preferably 11 to 23 mm.
3. The cooking utensil as claimed in claim 1 wherein said thickness of anodization is preferably. 50µ.
4. A process for the manufacture of a cooking utensil as claimed in claim 1 comprising the steps of suspending the utensil to be anodized into an electrolytic bath, containing an oxidising medium, subjecting the utensil to an anodizing treatment, removing the anodized utensil from the bath.

5. The process as claimed in claim 4 wherein said oxidizing medium, is an acid.
6. The process as claimed in claim 5 wherein said acid is preferably sulphuric acid.
7. The process as claimed in claim 5 wherein the utensil to be anodized has_a step extending horizontally and in a circular fashion across the sidewall of the utensil.
8. The process as claimed in claim 7, wherein a part of the sidewall of the utensil extending upwards from the step is optionally covered with a
masking agent.
. The process as claimed in claim 8 wherein said masking agent is
preferably a tape.
Dated this 24th DAY OF JANUARY, 2002.
I. BANERJEE OF L. S. DAVAR & CO. APPLICANTS AGENT