Granite, Marble, or Stainless Steel – To kasher (for year-round and Pesach), clean the countertop, wait 24 hours after its last use, and then pour boiling water over each part of the countertop. You may need to refill the pot several times. (It is not sufficient to pour on one spot and let the water run over the counter.) Make sure the material is a pure granite or stone. Sometimes they are really “composites” and therefore CANNOT be kashered.
Wood may also be kashered as stainless steel if it has a smooth surface and no cracks.
Porcelain Enamel, Dupont Corian® Solid Surface and Corian® Quartz Surface (formerly called Zodiaq®), Formica, Silestone – Star-K policy does not allow kashering of plastic or materials with plastic components.
- Year-Round Use: As long as the countertop is clean, it may be used for cold pots and food. Hot food should not be placed on it. If inadvertently hot food was put on the counter, the food will not become treif.
- Pesach Use: Clean and cover for cold food. Use cardboard or thick pad for hot food and utensils.
- Corian Solid Surfaces® : Certain types can be sanded down to take off a layer (the thickness of a piece of paper) and this would kasher the counter. This is because the non-kosher hot food penetrates only a thin layer of the counter. We suggest hiring a kitchen contractor to do the sanding.