Stoneware Dinner Set

Details

Stoneware thrown and fired to 1,220 C in Khurja, glazed in a plain matte that is fired into the body rather than printed onto it. This is the most consequential item on this shelf, because a glaze can release lead and cadmium into food and there is no way to see it, smell it or wash it off. So start with the numbers. Tested to ISO 6486-1, which is a 24 hour soak in 4 percent acetic acid at 22 C in the dark, the flatware here releases under 0.05 mg of lead per square decimetre and under 0.01 mg of cadmium, against ISO 6486-2 limits of 0.8 and 0.07. The katoris are hollowware and are measured the other way, per litre, at under 0.1 mg lead and under 0.02 cadmium against limits of 4.0 and 0.3. Every figure is measured on the eating surface, which is the only surface that matters. The mechanism is worth knowing because it tells you what to avoid everywhere else. Lead and cadmium in tableware sit almost entirely in on-glaze decoration: bright reds and yellows come from cadmium sulfoselenide pigments carried in a lead-borosilicate flux that has to melt at 750 to 800 C, well below the temperature the pot was fired at, so it sits on top of the glaze where the food is. These pieces carry no on-glaze decoration at all. The colour is in the glaze and it went through at 1,220 C, four hundred degrees above the temperature at which such a flux could survive. The second cheat is earthenware fired at 950 to 1,050 C and sold as stoneware. It is porous, it holds curry and odour, and its glaze crazes, and a crazed glaze is exactly where release starts. Water absorption tells you which you have: ours is under 1 percent by ASTM C373, earthenware runs 8 to 15 percent, and you can approximate the test at home by weighing a plate dry, soaking it overnight and weighing it again.

• Lead and cadmium release measured on the eating surface to ISO 6486-1, against the ISO 6486-2 limits, on every glaze lot
• No on-glaze decoration of any kind, which is where lead and cadmium actually live
• No decals, no printed rims, no metallic banding, no gold lustre
• Fired to 1,220 C, vitrified, water absorption under 1 percent by ASTM C373
• Glaze fit matched to the body and thermal-cycle tested, so it does not craze, because a crazed glaze is a leaking glaze
• Microwave, oven to 180 C, and dishwasher safe, all of which the fired-in glaze survives and a printed one does not
• Open stock forever, so one break is a plate and not a set
• Tone and speckle vary between pieces. That is the kiln, and it is not a fault
• It is heavy, 780 g for the 27 cm plate, and it chips if you knock it against a steel sink
• The foot ring is unglazed vitrified body, so it will mark a glass table. Felt pads or a cloth