Porcelain slabs are very resistant to heat and scratching. The surface does not burn or melt under a hot pan, and everyday knives and utensils rarely mark a matt finish.
They are not indestructible. A sharp, local temperature change can crack a slab, especially near a cut-out. Hard grit and ceramic or diamond tools can scratch it, and polished surfaces show marks more easily than matt ones.
Heat resistance
Porcelain is fired in the kiln at temperatures well above anything a kitchen produces, typically around 1,200 °C. It contains no resin binder, so heat does not scorch or yellow it the way it can mark resin-bound surfaces.
The weak point is thermal shock. If one small area heats quickly while the rest of the slab stays cool, the slab expands unevenly and can crack. The risk is highest at sink and hob cut-outs, narrow strips and edges with small chips.
- Advise customers to use trivets under very hot pans, especially cast iron straight from the oven.
- Ask fabricators to leave the gap around hobs that the hob and slab makers recommend.
- Do not place portable gas burners or hot plates directly on the slab.
Testing for heat
Thermal shock resistance is tested to ISO 10545-9. Ask for that report if you sell slabs for kitchens. Our guide on tests for countertop slabs lists the others.
Scratch resistance
Porcelain is harder than most things it meets in a home, including steel knives. That is why matt and textured slabs rarely show cutting marks. Mineral hardness is explained in the Mohs hardness of vitrified tiles.
Finish changes what you see. A high-polish or glossy glaze reflects light, so very fine scratches and wear paths become visible. A matt or soft finish hides them. Sand and grit carried on shoes or under heavy pots are the most common causes of scratching.
- For worktops and busy floors, matt, satin or soft-polished finishes show less wear.
- For glazed slabs, ask for surface abrasion results to ISO 10545-7, often reported as a PEI class.
- For unglazed full-body slabs, ask for deep abrasion results to ISO 10545-6.
- Advise customers not to cut directly on the slab, partly to protect knives.
Stains and chemicals
Because porcelain absorbs almost no water, most food and drink stains wipe off. Polished slabs can have tiny surface pores opened during polishing, which some factories seal. Ask whether the slab is treated, and with what.
Stain resistance is tested to ISO 10545-14 and chemical resistance to ISO 10545-13. Strong acids or hydrofluoric products can damage the surface, so give customers a short list of cleaning products to avoid.
What to tell your customers
Honest guidance protects you from claims. Describe heat and scratch resistance as high, not unlimited, and explain the few things to avoid. Put the factory's care guide in every crate or on your website.
Most worktop complaints about cracks trace back to fabrication, such as sharp inside corners at cut-outs. Our guide on cutting, drilling and edging slabs on site covers this.
Next step
We check that test reports cover the finish and thickness you buy, and collect care and fabrication guides from the factory. To plan a worktop range, book a free sourcing review.