Kashruth of Terra Cotta

Question

What are the halakhoth regarding unglazed terra cotta flower pots? Does it absorb? Can it be kashered, and if so, how?

Sephardic rulings preferred, but will take any sources.

Answer 1

terracotta is the same as any unglazed earthenware vessel. It absorbs the non-kosher material but cannot ever have it removed.

Kashering dishes

/Leviticus 6:21 says, “And the earthenware vessel in which it was cooked shall be bro­ken; and if it was cooked in a brazen vessel, it shall be scoured, and rinsed in water.” This verse is the basis for certain rules of kashering dishes, and what may or may not be

Unglazed earthenware cannot be kashered at all, as the porous ceramic permanently absorbs juices and flavors from foods.

CRC states explicitly that earthenware pots (while they do absorb), cannot be kashered.

The following items may not be kashered:

China, pottery, earthenware, cement/concrete and enameled pots may not be kashered.

This is because these materials do not allow what they have been absorbed to be re-emitted and "canceled out" by the boiling water or fire that is used to kasher other mterials.

Answer 2

Terra Cotta is what the Tora and Talmud called Heres. Kelei Heres. cannot be Kashered with Hag'ala, as we will show in Shulchan Aruch.

• The Shulhan Aruch Orah Chayim Siman 451 Sayf 1
  

Ceramic dishes that have been used for hametz the whole year, even if they were used for oats or other grains, should be wiped well such that there is no noticeable hametz left, and then it is permitted to keep them until after Passover and use them either for what they were used for before Passover or something different. They should be hidden on Passover in a hidden place where one does not normally go, lest one come to use them on Passover. It is good to close them in a room and to hide the key. But refiring it in fire does not work for any ceramic item that was used for hot things, even if it was not used on the fire and boiling liquid was just poured into it. Rem"a: There are those who forbid even for the second container (the Magid chapter 5). Even if they are filled with coals, we are concerned that he will be worried that the containers will crack (meaning that they will break) and will not do a complete refiring. However, if he returns them to the furnace where they make new ceramic items, it is permitted. Because they are sent into a big fire like this, clearly he will not be concerned that they will break. But this is not true of our ovens. Rem"a: For every object that needs to be made white-hot or scalding, it is forbidden to use it even for cold things without kashering it (Mordechai at the beginning of Chapter Kol Shaah). See in Yoreh Deah Chapter 121.

If the pot is glazed, is the surface layer regarded as glass, "Keli Zechuchit, this is a next question and what is the status of Zechuchit too.

When a terra cotta pot is used with boiling aliments, there is no way to make Hag'ala.

• Theoretically, it is possible to heat up to high temperature to burn organic absorbed material. But the Rabbis fear that he's not going to do it right because he's afraid of damaging the pot.
  
  

The source is in diverse Gemoros.

Pessachim 30B

וכי תימא ה''נ ליעבד ליה הסקה מבפנים חייס עליה משום דפקעה

And should you say, here too let him burn it [the pot] out from within, - he would spare it, lest it burst.

The Magen Avraham in OC 451 sk 4, says, quoting the Gemara Zevahim 95b-966a that for an oven in terra cotta, it's possible to make it Kasher by heating it white from the inside.

• In Leviticus 6, 21, the Torah addresses the future of utensils on the inside of witch we put the Kodashim when they were hot foods. There is a difference between terra cotta and copper.
  

What is the topic of this verse, not Kashrut!?

The Talmud asks in Zvachim 96a.

Then why should the pots in the Temple be broken: let them be returned to the kiln? - Said Rabbi Zera: Because kilns are not permitted in Jerusalem.

The reintroduction of a pot in the oven is as a creation of a new pot (may be according to tosfot if the pot was impure before the second baking, it will become pure as a new pot). I did not find this Din in Shulchan Aruch, maybe that in this case too, we are concerned that he will be worried that the containers will crack.

(The interesting here is that the Torah here seems to treat a an other issue than Kashrut. (It is very interesting to read Rabenu tam the Tosfot in Zevahim. The utensil is not repaired, it became))