A kashered worktop may be used as it is and need not be covered. Where it cannot be kashered, it must be covered — with a material that is not porous and will not easily rip or tear. Some have the custom to do both.
Because the laws here are genuinely complex, the sound general advice is to cover unless you are confident the surface was properly kashered, and to have someone who knows the laws oversee the process.
The dispute behind the modern materials
One disagreement runs underneath most of this. There is a difference of opinion as to whether a material not mentioned in the Torah can be kashered at all — and plastics and most modern composites are exactly that.
One ruling holds that plastic may be kashered for Pesach. With an important qualification: if it is a plastic that might be damaged in the process, it may not be kashered — because someone afraid of ruining their worktop will not kasher it properly. The concern is about the person, not the plastic.
That reasoning is worth noticing. A material can be theoretically kasherable and practically excluded because of how people will behave around it.
Material by material
| Surface | Position |
|---|---|
| Plastic laminate | Subject to the dispute above; seams between the laminate and the board beneath collect chametz through the year |
| Acrylic solid surface | May be kashered in theory — but it scratches and stains, and where there are scratches or stains kashering does not help and it must be covered |
| Wood and butcher block | May be kashered, provided there are no cracks that could trap chametz. In a butcher's shop the surface was sanded down; that is not practical at home |
| Natural stone — granite, marble, limestone, soapstone, slate, onyx | May be kashered. Check the surface is not finished with a synthetic, which would need to be kasherable in its own right |
| Quartz resin | May be kashered. Unlike natural stone it is not porous and needs no sealing |
| Glass, ceramic and porcelain tile | Must be covered — the grout between tiles is porous |
| Concrete | Must be covered |
| Any surface held down or joined with caulking | The caulking is its own problem |
What actually decides it
Reading down that list, the material matters less than three things:
- Seams and joins. Anywhere two pieces meet is where chametz collects and where kashering does not reach.
- Cracks and scratches. A surface that is sound can be kashered; the same material scored or damaged often cannot.
- Grout and caulk. Porous filler between hard surfaces is frequently the reason an otherwise kasherable worktop has to be covered.
So the useful question is not "what is my worktop made of" but "what condition is it in, and where are the joins".
What your surface needs is a question for your rav, ideally with a look at the actual worktop. See also the three methods of kashering.
Where this comes from
- Shulchan Aruch, Orach Chaim 451, on kashering surfaces
- Guidelines on kashering countertops and stovetops; ruling of Rabbi Gedalia Dov Schwartz on plastic