From: Rabbi Moshe Sofer
To: Rabbi Moshe
A sieve used year-round with chametz was accidentally switched with a thoroughly cleaned Pesach sieve and used to sift ground matzah flour. The Chasam Sofer upholds the local rabbi's lenient ruling permitting the earthenware utensils used, citing thorough cleaning and significant financial loss.
Source: Shu"t Chasam Sofer OC §138