If one has several used pots but does not know if they are dairy or meat, but knows that treif has never been cooked in any of them. Plus these pots have not been toveled. Is it permitted to tovel the pots then kasher them and make a new designation for them as either milk or meat?
Please send sources.
It is permitted to perform hag’alah on the pots (after being tovel them), and designate them anew.
According to the basic halachah it is permitted to change the designation of a utensil from meat or dairy (or vice-versa) through hag’alah. Hag’alah purges the taste that is absorbed in the utensil, and therefore permits it for any use.
However, there is a long-standing and widely practiced custom not to do so on a lechatchilah level, since the Rabbis were concerned that people would “get away” with one set of utensils which they would constantly “kosher” from dairy to meat and back again, causing mix- ups and confusion (see Magen Avraham 509:11; see also Sha’ar ha-Melech, Yom Tov 4:8; the custom applies only for Ashkenazim: see Kaf ha- Chayim, Orach Chaim 509:45; see also Peri Chadash Yoreh De’ah 97:1 and Aruch ha-Shulchan 89:17 and 121:11 for further discussion of the custom).
Because there is no formal prohibition involved, poskim are lenient under a variety of extenuating circumstances, or on a bedieved level (see for instance Maharsham 2:241; Lecham ha-Panim 121, quoted by Darkei Teshuvah 121:59; Be’er Moshe 3:105; see also Mishnah Berurah 451:19).
In the case of the question, there is a doubt as to whether the utensils are meaty or dairy, and therefore it is possible that the custom won’t apply at all, because there is no transfer from one type to the other. In addition, it is something of a bedieved situation, because without kashering the pots won’t be usable for either type. Therefore, it is permitted to kasher then and designate them for either use.