The kettle to be used for cooking should be durable and free from seams
or crevices which are hard to clean. It should have perpendicular sides,
and the cover should be as flat as possible and be provided with a deep
lid fitting well down into the kettle, in order to retain the steam. A
kettle holding about six quarts is a convenient size for general use.
Tinned iron kettles should not be used in a fireless cooker, for,
although cheap, they are very apt to rust from the confined moisture.
Enamelware kettles are satisfactory.