why the vessel of copper and brass need kalai
Answers
in Kalai a layer of tin metal is applied on the copper and brass vessels.
The vessels of copper and brass need kalai to protect them from wearing out and keeping them safe for cooking.
• Kalai is a word of Arabic origin, meaning white wash or tin.
• As the meaning suggests, kalai is the process of coating copper and its alloys, like brass, with a layer of tin.
• Copper vessels are used because of their high conductivity of heat.
• But, over time, copper vessels can react with atmosphere and get oxidized into copper oxide.
• This forms a layer of copper oxide on the vessel, making it unsuitable for use.
• Also, when water is stored in a copper vessel for a long time, the copper starts dissolving in it, thereby poisoning the water.
• Therefore, a layer of tin is coated on the inner side of copper vessels from time to time, to prevent the vessel from reacting with atmosphere, and to keep it safe for cooking.
• Also, tin has an almost equal heat conductivity to that of copper. Therefore, the time and quality of cooking is also not hampered.