Blech - Unblech

An unblech, or K'Deira Blech (lit. "pot blech", commonly referred to as "water blech"), is also used to heat up pre-cooked food on the Sabbath, but utilizes different halakhic mechanisms from a standard blech. An unblech consists of a shallow metal pan filled with hot water and covered by another metal pan, and thus is akin to a pot of warm food for halakhic purposes. As such, it may be more flexible than a standard blech for halakhic purposes. However, the temperature of an unblech is limited by the boiling point of water and is not as hot as a typical blech.