It is a vessel made of tin. Tin has a low melting point of 232°C. This cookware needs attention when use in kitchen. When you make this rasam in this vessel, it is always first filled with the ingredients of the rasam before it goes onto the fire and that includes water too. It is due to the low melting point of the vessel the seasoning is done in a separate utensil and added on top in the vessel filled with boiled rasam. If instructions not followed, the melting point is achieved you will be left with a mass of shiny silver metal and the burners flooded in rasam. The secret to this rasam is as much the dedication as the metallic sweet taste imparted to it.