By Rabbi Yair Hoffman for

It has been said that there have been Halachic Analysis articles on pretty much everything but the kitchen sink.

Well, now, with the following article, this can no longer be said.

It is the latest rage in kitchen sinks for both beauty and long-lasting durability – Silgranit.

Bruno, the company that produces it, used advanced engineering to produce a material that is non-porous, repels water and liquids, and withstands everyday wear and tear.  Silgranit is stain- resistant, easy to clean, and reduces bacteria growth by an average of 98%. They patented the technology and call it, “Hygienic+Plus surface protection.”

It is quite stunning in appearance, and its rapid growth in regard to the redesigning kitchen market has been equally stunning as well.

Our question however, solely concerns the following point:  Can Silgranit sinks be kashered for Pesach?  And if not, can they be kashered at all?  The standard method of koshering under discussion is through something called hagalah – a method of koshering where boiling water


Before we get to the halacha – let’s first try to understand what it is.  Silgranit is made from finely ground Granite quartz (up to 80 percent) and 20 percent acrylic. It can withstand heat up to 536 degrees Fahrenheit.  There are pigmentations that are clearly added, because it comes in nine different colors.  Although the company has responded to the author, they have, understandably, not yet been forthcoming with this author as to what else is added to the “mix”  out of concern for proprietary issues. Generally speaking, engineered stones contains quartz, polymers, resins, and pigments – but at different percentages.  Silestone and Caesarstone are comprised of somewhere between 90 to 93 percent quartz suspended in binding resins. Corian, on the other hand, contains 66 percent natural minerals such as bauxite, and 33 percent acrylic resins.

There is a possibility that Bruno did send more details to Zomet in Eretz Yisroel. This author has been in contact with Zomet for access to that information.


Let us now delineate and explore three different halachic areas.

  • Firstly, what is the halacha with reconstituted stone?
  • Secondly, what is the halacha regarding kashering plastic? Is it different if we are discussing a hard acrylic?
  • Finally, what is the halacha when discussing a combination of materials? Do we follow the majority of the composite? Or are we concerned about the minority section of the composite?


The Gemorah in Psachim 30b discusses something called, “Kunya” – a vessel made of pottery covered in lead – that was used for chometz.  The students of the Yeshiva asked Ameimar:  May Kunya be kashered for Pesach?  [Warning: nowadays, lead utensils are known to be toxic and hazardous].

The Gemorah clarifies its question – that it is not discussing when the lead is combined with “tzrif” (alum according to Rashi, probably potassium aluminum sulfate). Rashi in Kesuvos 107b explains that lead itself when it covers the pottery smooths it, but when alum is added to it, it dirties it and causes it to absorb.

Back to Psachim, Ameimar answered that these vessels sweat on the outside and therefore, we see that it absorbs through the lead into the pottery and are thus not kasherable through hagalah. He then states that the Torah testifies that cheres – never comes out of its Dofyo [or Dofno].  Dofyo means its blemishes [Dofno means its walls]. Either way, it means that it is not kasherable through hagala.

Ameimar is referring to the Pasuk in parshas Tzav regarding the meat of a Korban Chatas (Vayikra 6:21), “An earthen vessel in which it was boiled shall be broken..”

This is because the flesh of a korban may only be eaten up until a certain time.  After that time, the leftover meat is considered “nosar” and is forbidden food at this time. The taste of the nosar remains in the vessel in which it is cooked.  An earthen vessel is broken, a metal vessel must be kashered.

Earthenware, cannot be kashered through hagalah.

{As a parenthetic note, Rav Yoseph Karo in Orach Chaim (451:26) rules that glass may be koshered , basing himself on a Ran in Psachim.  The Ramah writes that the custom is to be stringent (this is the Mordechai’s opinion). The reason, as explained by the Mishna Brurah, is that since glass comes from sand originally, they treated it like sand.  The Mogain Avrohom writes that bdi’eved, if it was done already – then glass is permitted.


The first to discuss the issue of finely ground stone that were reshaped into a vessel were Rav Nosson Nata Segal Landau (1841-1906), author of the Kmo HaShachar, Rabbi Tzvi Hirsch Shapira (1850-1913), author of the Darchei Teshuvah (121:25) and Rabbi Yehudah Leib Landau (1823-1900), author of the Yad Yehuda (69:81).  Both of these latter Poskim forbade the koshering of reshaped stone.  These Poskim refer to expensive bowls that were made in Russia in this manner and they equate them to being similar to porcelain.  The Yad Yehudah writes so in a definitive manner.


To counter this argument, It is certainly possible, however, that the manufacturing processes then were not as sophisticated as they are now.  Perhaps the concern was that the heat would cause the stone to crack or crumble and that is why these Poskim forbade it.  Now the new processing has made the combined mixture of acrylic and granite completely heat resistant.  The Darchei Teshuvah also cites Rav Landau’s sefer entitled “Kmo HaShachar” as presenting the distinction between natural stone and crushed stone only as a possibility.  If this understanding of the Kmo haShachar is correct, then perhaps we have a “safaik” in halacha on this very issue.  Another possible “safaik” is the first issue – where the manufacturers may have created a truly heat resistant material.

There may be yet another factor.  There are times when the Chasam Sofer (YD #95) has recommended implementing three hagalos and not one – even on a kli cheres – a porcelain dish.  True, this is only when the hot item dripping down was considered nifsak hakiluach – where it was no longer connected to the original vessel – we do see that the concept is used, and here we are not sure whether it would even be considered cheres.  The Pri Magadim, by the same token. in several places (Sifsei Daas 92:38; MH 68:9:4) distinguishes between food and a hard and solid vessel.  True, he also only raises this point in regard to a liquid that was disconnected from the original vessel – but, as mentioned earlier, we are not sure that this material should be considered like porcelain.

Finally, there is the view of Dayan Yitzchok Yaakov Weiss zt”l (1902-1989) in Minchas Yitzchok Vol. III #67 who writes that there are Poskim that disagree with Darchei Teshuvah and Yad Yehudah on this matter.  The Kochvei Yitzchok #27 also makes the same point. I am told that this was the view of Rav Elyashiv zt”l as well.


Rav Elyashiv, Rav Vosner, and Rav Nissim Karelitz (cited in MiBais Levi Kovaitz #9 p.15) were all of the opinion that one may not kasher plastic with hagalah.  Rav Moshe Feinstein zt”l was also of that opinion (See IM OC Vol. II #92), but was lenient in regard to using hagala for a Teflon coated frying pan that was no longer a ben yomo because it was only a safaik Derabanan.

On the other hand, Dayan Weiss (Minchas Yitzchok. Vol. III #67) was of the opinion that plastic may be koshered with hagalah. This was also the view of the Chelkas Yaakov (Vol. II #167) and the Ohr L’Tzion (Vol. III 10:13).

In Eretz Yisroel, virtually all Poskim are only lenient regarding plastic when it is combined with another leniency.  In the United States, however, the only is lenient and allows it at the outset (conversation with the author on March 8th, 2021).  Rav Yisroel Dovid Harfenes, one of the leading Poskim in the United States, is also lenient and allows the koshering of plastic with hagalah.


Rav Elyashiv’s view (cited in Siddur Pesach K’Hilchaso chapter VIII footnote #49) was that there were three situations where on can rely on the lenient opinion that allows for koshering plastic with hagallah.

  • When the absorption into the plastic was only through a kli sheini.
  • When we are dealing with koshering the handles of a pot
  • When the Teflon coat of a new frying pan is smeared with an animal fat.

There is also the view of the Shvus Yitzchok (laws of microwave p. 53) that one can do hagalah three times for something that absorbed something permitted at the time.


The Maharsham in his responsum Vol. I #53 rules that we follow the majority of the vessel – whether the outcome is stringent or lenient. However, he writes to be stringent in all situations.  The Yad Yehudah (69:33) as well urges stringency even when only a minority of the composite material is a material that cannot be kashered. On the other hand, Dayan Weiss (Vol. III #67 and Vol. IV #114:4) indicates that one may follow the majority.


It seems that there is enough room to be lenient and allow for hagalah when dealing with Silgranit – even for Pesach.  If one wishes to be stringent, then one can perform the hagalah three times.  If one wishes to be even more stringent – then one can cover the sink with an insert for Pesach.  But, as in all matters of halacha, speak to your own Rav or Posaik.  You may want to mention to your Rav the aforementioned halachic sources and ask what his thoughts are.

As reported by Vos Iz Neias