Q: I bought a box of white ironstone china at an auction. Some of the older pieces are in good condition, but they have brownish stains that I’d like to remove. Is there a way to make ironstone white again? — J.T., Ossining
A: Congratulations on a nice auction find! Ironstone, a glazed earthenware that was developed as a cheap alternative to fine porcelain, was first made around 1813 in Staffordshire, England, where potteries have been turning out goods since the year dot. (Or the 1600s, anyway.) Most of the white stoneware produced there wound up on our side of the Atlantic, where it was popular because it was so durable and affordable. These days, old, marked pieces in good condition are highly collectible.
There’s actually no iron in ironstone — it was probably sold under that name to suggest how tough it is. Early pieces often have a blue-ish cast from the cobalt that was part of the mix; later ironstone is usually more cream-colored.
If the brown stains on your ironstone haven’t deeply penetrated the clay itself, you can remove them by soaking the pieces in 3 percent hydrogen peroxide, available at your friendly local drugstore. You’ll need a container with a lid, like a plastic storage bin, big enough to hold the piece completely submerged in hydrogen peroxide. Put the lid on to stop the peroxide from evaporating and leave the china to soak for two or three days.
Wait for a sunny day, then remove the ironstone piece and put it in sunlight. The hydrogen peroxide will vaporize and the brown stains should disappear and leave the piece white again. You can put the ironstone into a cold, electric oven and let the temperature rise to no more than 200 degrees. Turn off the oven and let the piece cool before washing it. Do not use a gas oven for this step. Although a solution of 3 percent hydrogen peroxide isn’t flammable (like the higher concentrations that hairdressers use), after the water content evaporates, the fumes plus a flame can cause an explosion. It’s unlikely, but still, I’d stick with sunlight.
A few more tips: