1 – A person who used the knife to cut a non- kosher fish it, the knife and fish were cold. Does the knife need kashering, or will washing the knife suffice? She is allowed to cut a Kosher fish?
2 – In case it does need, is burying the knife 10 times on the floor and washing serves as kashering in this case?
Thank you for your question.
Since the fish and knife were cold there is no need to kasher it. Techinically the proper thing to do would be to insert it in hard ground 10 times, however many poskim say that we don’t really know nowadays what is the correct type of ground to insert the knife. Additionally, numerous poskim say that washing the knife off well with steel wool, will suffice to clean the knife and then it can be used.
Emes L’Yackov ftnt. 38, Ohel Yackov 94 ftnt. 60, Davar Charif chap. 8-10 ftnt. 49, Hilchos Basar B’chalav chat. 9 ftnt.63, Ma’adnei Osher 45, Reach Habesem 3 ftnt. 28, Zera Shmuel -Bsar Bchalav ftnt. 248,