Question:
Can a metal frying pan that was used for milchigs be kashered so it can be used for fleishigs?
Answer:
According to the strict letter of the law one can kasher through “libun” a metal frying pan that was used for milchigs so it can be used for fleishigs. But the accepted Ashkenazi custom is to refrain from doing so because of the fear of error and mistake.
Never the less there are two loop holes a) to make the utensil “treif” first and then when it is kashered one can switch uses b) if one kashurs the vessel for Pesach one can switch around.
Source:
O:CH 509:5, Mishnah Berurah 25, O;CH 451 Mishnah Berurah 19