My kitchen knives need sharpening. I have a client who is a former meat cutter, non Kosher. He’s offered to sharpen my knives. Can they be rekashered? If so, how?
If the sharpener of the meat cutter was clean, there is no need to kasher it. This is because absorbed taste only goes from one vessel to another if there is liquid there. Therefore, if the sharpener is clean, it is permitted without a problem. If the gentile takes the knife and there is suspicion that he might have used it for his own non- kosher foods, then the knife would need hagala, not because of his sharpening it, but because if the fear that he might have used it for his own personal use.
Shevet Hakehosi 3-342, Bais Yosef Y:D 122-9 in the name of the Mordechai.