Q. My mother has a very old fine china porcelain set of dishes that has not been used for twenty years.
She does not remember whether they were used for meat or milk. Can we now Kasher them and use them for Pesach?
A. Horav Aharon Miller's Shlit'a opinion is that in need they could be Kashered by immersing then three times in boiling water (on the fire) and changing the water each time.
It would be advisable if in doubt if Tevila was done on them, to repeat it.
Horav Shlomo Miller's Shlit'a opinion is that it is preferable not to use the set for Pesach.
Rabbi A. Bartfeld as revised by Horav Dovid Pam, Horav Aharon Miller and Horav Chanoch Ehrentreu Shlit'a