Throughout all of Yoreh Deah Chelek Alef and Hilchos Pesach (and perhaps other places in Shulchan Aruch as well) we see the idea of “blias” by celim.
This is all true of a metal pot. However, a glass pot, according to the Machaber, doesn’t take in any blias at all. On the other side of things, if one has a pot made of “cheres” (that one can never kasher…)
I’m having a difficult time understanding how this din is still relevant to today’s pots. Is there really a taste left inside of a metal pot? Once upon a time a metal pot that was cooked in over time would slowly become dirty, grimy, filthy, covered in black, clearly a used thing. One could look at this and understand that there is a “taste” left in the walls of the pot. However, I don’t see how this is true of a normal metal pot in today’s market, which is smooth, finished off, and more or less retains it’s original color and look and stays clean over time. Where is the “taste” in the walls of this pot? If someone would cook milk or meat in it and then cook water in it, would the water have any taste to it (assuming the pot was cleaned in between)?
While I don’t see any posek using this argument even as a “tziruf” to be makil in a question of issur v’heter, still, I’m looking for any poskim that perhaps spoke about this or entertained the possibility (or any reason why this simply is not the case.) Maybe today’s “metal” pots are more like a glass pot?
It is generally true that in today’s pots we don’t find much absorption of taste. I believe that if one were to thoroughly clean the cholent pot after Shabbos, and then boil water in it, the taste of the cholent won’t be felt.
However, poskim do not generally mention this consideration, for two reasons:
1. It is assumed that the prohibition of beliyos applies to materials: Chazal decided which materials absorb taste, and all pots and utensils made of these materials are therefore subject to the laws of beliyos. This idea is stated by Rabbi Moshe Sternbuch (5:115).
2. Under the assumption that today’s utensils don’t absorb taste, we will end up erasing a large part of the Shulchan Aruch. This is something that authorities are not very keen on doing, and such a radical change can lead to many pitfalls.
3. The entire idea of technological advances making changes to the halachah is something poskim are fearful of, because it brings us back to the reform debates of the 19th century.
I have heard of some poskim that did use this consideration as a tziruf, but have not seen this written, and it cannot be relied on.