Can a Granite Countertop Be Koshered?

A completely smooth, uncoated, single slab of granite can indeed be koshered1. Here is what you would need to do:

a) Scrub it completely clean.

b) Do not place hot items on its surface for 24 hours prior to the koshering.

c) Pour boiling water over the entire surface of the (completely dry) countertop.

d) Run a hot rock or brick, or an electric iron, over the countertop's surface so that the water on the countertop reaches a boil.

For safety purposes, if you use an electric iron, make sure that the cord is unplugged before you use it to kosher the counter. Also, no matter what you will use, boiling water and hot rocks are dangerous. Plan the logistics in advance and exercise appropriate caution!

This procedure renders a counter kosher, and can also be used to kosher a chametz countertop for Passover. Nevertheless, for Passover purposes only, many will cover the counter's surface for the duration of the holiday.

Yours truly,

Rabbi Menachem Posner

Footnotes

Rabbi Jacob ben Asher (Tur Orach Chaim 451) records three opinions regarding stoneware:
a) Rabbi Yitzchak of Simpono held that stone is not porous and that simply rinsing is sufficient to render it kosher.
b) On the other extreme, Rabbi Hai Gaon felt that stoneware is best compared to earthenware, which needs to be re-fired in a kiln in order to be purged of any non-kosher residue it may have absorbed.
c) Rabbi Yitzchak Alfasi was of the opinion that stoneware can be koshered through application of heat (as discussed in the article).
Rabbi Jacob ben Asher himself followed the approach of Rabbi Yitzchak Alfasi. This ruling was accepted as the final Halacha by the later authorities as well.

By Menachem Posner

Rabbi Menachem Posner serves as managing editor at Chabad.org, the world’s largest Jewish informational website. He has been writing, researching, and editing for Chabad.org since 2006, when he received his rabbinic degree from Central Yeshiva Tomchei Temimim Lubavitch. He lives in Chicago, Ill., with his family.

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11 Comments

Lawdoc June 10, 2024

Most granite countertops nowadays are treated with a sealant (available in Home Depot, Lowe’s, etc.), to prevent absorption into the granite, which is recommended to be reapplied at certain intervals. Can this be considered as being kosher, or koshered for Pesach?

Also, no mention was made of the handheld steamers. Would these be effective, as they are much easier — and safer — to use than pouring boiling water, etc……? Reply

Menachem Posner Chicago May 4, 2016

The Iron Your question is essentially the same question that can be asked regarding the pot in which you heat the water. The answer is the same. Make sure not to use it with hot chametz for 24 hours before you do the koshering, and whatever flavor is there is considered to be be distasteful (pagum). Reply

FrumbutSane Uk April 21, 2016

Ridiculous suggestion to run hot anything over counter top. How does the rabbi propose to kasher the electric iron first - assuming it's been used for ironing and may have been in contact with starch and such like. Reply

Yoni May 29, 2023

in response to FrumbutSane:

I've kashered many kitchens. Breifly, in the real life situation where everything of cleaned first, not used 24 hr, plus the iron vibrates as the boiling-bubbles fiercely escape from the heat of the iron, there is no such kosher concern for the iron itself. Plus, IF YOU ARE SUFFICIENTLY CAREFUL, using an iron is tbe best for a few reasons, immediately apparent to those who use them for kashering. One of these points answeres your first comment: because of the fierce bubbling, even as one presses down, there remains a separation between the formica's Surface and the iron itself. That separation is the water that is literally at the boiling point, bubbling, which makes it kosher - and does not allow the formaica to heat beyond 100 / 212 degrees (centigrade/fahrenheit - at much higher elevations, like in mountainous regions, water bubbles at slightly lower temperatures, and that is okay in those places, it's the rolling boil [fierce bubbles] that one is looking for) . Reply

Lawdoc June 10, 2024

in response to Yoni:

Is Formica actually kasherable (the branded named product — though it has become a “generic” term for similar products which may not be manufactured from the same “récipé”)? Reply

Menachem Posner Chicago February 22, 2016

To BB Imagine this website were one that dispensed information and tips for people living with terrible allergies. Would you wonder why they care how to remove allergens from their food? We Jewish people have a soul allergy to anything forbidden by the Torah, and it is important for us to keep our souls healthy. This means going to whatever lengths needed to ensure that we only consume 100% kosher (and on Passover, kosher for Passover). Reply

BB lexington February 20, 2016

brother why do you care? I am seriously asking this. Perplexed, not anti-kosher. What does this have to do with modern day life? Sorry it popped up on my email and I just don't get it.... Reply

Anonymous Far Rockaway, NY April 21, 2011

Other Counter Tops The Star-K Pesach Directory says that those other counter tops mentioned in your query cannot be kashered but must be cleaned and covered with some impermeable material that does not conduct heat (slabs of wood or thick plastic but not aluminum foil). Check with your local Orthodox Rabbi for more guidance on kashering the kitchen for Pesach. In advance of Pesach next year, get the Star K or O-U kashrus organizations guidelines for kashering the kitchen and preparing for Passover, they are very helpful and detailed with practical advice for the modern Jewish homemaker. Reply

Yoni May 29, 2023

in response to Anonymous:

Star K seems to stand alone in their view, adding this note to its discussion of countertop materials: "Star-K policy does not allow kashering of plastic or materials with plastic components." There are other long-standing reputable kosher certification agencies that follow the majority opinion which is more lenient by far, when it comes to counter top materials. Look at CRC, OU, OK to see this for yourself. Reply

Anonymous Portland, or April 21, 2011

Other counter tops What is the situation with respect to counter tops like Zodiac or Silestone, which are made of crushed rock embedded in some matrix? (I believe the matrix is a very hard plastic like acrylic) Reply

Zev Melbourne, Australia March 21, 2010

Bench top is not a 'Kli' It appears to me that in the passage you referenced, Tur is talking about a stone vessel (Kli) used for cooking and not a bench top. A vessel has a much more stringent status because food is cooked in it. A bench top may have hot food put on it, but it never serves as a 'Kli rishon'(the vessel food is cooked in). As such, i don't think it would require such stringent kashering. Reply

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