Can Caesarstone quartz counter tops be Kashered? Do you have recommended materials for a new kitchen’s counters (other than granite, which is expensive), that would be easy to be Kashered if necessary in the future?
Engineered quartz resin counter tops is a man-made material made to look like granite or marble. They are made from a combination of stone, synthetic resins and pigments and is different than natural stone in that it is not porous and thus the surface does not need to be sealed. Common brands are Cambria, Silestone, Zodiaq, and Caesar Stone. These may be Kashered, as they are made from stone (see Shulchan Aruch Orach Chaim 451:8).
There are differences of opinion whether one may Kasher synthetic materials, especially for Pesach. Even those that are stringent not to Kasher synthetic materials, may be lenient in this case, since the primary material used in the counters is stone. The synthetic resins are a small amount in order to bind the stones together. Even though not all follow the majority material regarding Kashering (See Minchas Yitzchak 4:114:4), in this case there is room for leniency. Nonetheless, some are stringent not to Kasher quartz counter tops. Generally, many have the custom to cover counter tops even when Kashered, since it is difficult to properly clean and Kasher, in addition to other reasons.
Other materials available mainly for commercial usage are stainless steel, copper, and zinc, which may be Kashered, though not usually used for home use today.
Some people have counter tops made from butcher block or wood which may be Kashered, but only if there are no cracks, and therefore not practical.
Natural stone, though somewhat expensive, is easy to clean and may be Kashered, regardless of the sealant used for coating the stone. Common materials are granite, marble, limestone, soapstone, slate, and onyx.
Plastic laminate is a hard plastic material laminated on a thin piece of wood. Common brands are Formica, Pionite, Wilsonart, and Nevamar. Many maintain that these cannot be Kashered, aside from the fact that often there are seams combining pieces of laminate together where food often collects and is therefore difficult to clean before Kashering.
There is another popular counter top material which looks like stone but is acrylic or polyester. Common brands are Corian, Staron, Swanstone, Gibraltar, Surrell, and Avonite. Not all agree that these may be Kashered, and even if they are Kashered, one has to make sure there are no cracks, scratches, or stains.
Glass, ceramic, cement, and porcelain counter tops may not be Kashered.