Kedairah Blech (Passover) Status: Q. Is it possible to kasher a kedairah blech for Pesach? A. Yes, it can be kashered with hag’alah. The kedairah blech, a.k.a. the “un-blech”, has two parts, a pan and a cover. The first step is to clean the pan and the cover thoroughly, and not use them for 24 hours. The pan should then be kashered by filling it with water and bringing that water to a rolling boil. The top of the cover (i.e. the side which comes in contact with the pots) must be submerged into boiling water. One possible way to do this would be by placing the cover upside down in the pan as it is filled with water, which is brought to a rolling boil (as described above).