PLAY IT SAFE BEFORE USE
Take time to find out what’s lining your old metal moulds, writes Jeanne Huber.
Q I was given five metal moulds, each two inches high and four inches across on the top and two inches across on the bottom. They are tarnished, perhaps from baking? Is it possible to restore them for baking?
A Yes, it’s possible, but you might want to take the pieces to a metal plating shop to figure out first what you’re dealing with.
Allison Fishbein, owner of Metro Plating and Polishing in Kensington, Md., and Jim Hamann, owner of East Coast Tinning in East Greenwich,
R.I., both said that it’s hard to determine just from the (reader-submitted) photos whether your moulds are silver-plated or tin-plated. But people who work in metal-plating shops can tell at a glance whether a silvery-coloured metal is tin or silver, Fishbein said. If your moulds are coated with tin, there’s a chance the tin has merely discoloured from heat, or perhaps bits of food are stuck to the surface. In this case, you may be able to use them as is.
“Tin will change colour,” Hamann said. “It will become mottled, battleship grey, even black. But that’s what tin does. If you try to scrub it away, you just wear the lining away.”
If the moulds were plated with tin but the tin has worn off in spots, whether they are still safe to bake with depends partly on whether the underlying metal is copper or steel. Test with a magnet, which won’t stick to copper but will stick to steel (assuming it’s regular steel and not certain types of stainless steel). Cooking in steel containers that have a little rust isn’t a health hazard, however, cooking acidic food in a container with exposed copper can, in sufficient quantities, allow enough copper to leach into the food to cause nausea, vomiting and diarrhea.
Lining copper with tin makes a copper container safe for cooking food because tin doesn’t react with acids. That’s why it has been used for years to line steel cans, as well as a wide array of cooking utensils and moulds. Copper pots, which are prized by many cooks because the metal transmits heat so well, are typically lined with tin. There are whole businesses that specialize in restoring the lining of pots.
Lining a pot with tin basically consists of ridding the surface of oxidation and other contaminants (recipes for this include diluted muriatic or sulphuric acid) and heating the metal to about 450 F (230 C), the melting point of tin. Molten tin is then ladled in and swirled around to coat the surface, or it’s rubbed on with a soft cloth, which is why the process is also called “handwiped” method.
“You’ll see some wipe marks in the finished product, but it will last much, much longer than electroplating,” Fishbein said.
If your moulds turn out to be silver-plated, Fishbein recommends having them tin-lined on the interior if you want to use them for baking. Silver plating, which her shop does, is fine for decorative pieces. Little has been written about baking in silver-plated containers, so she’s uncomfortable recommending it for cooking. She has no reservations about tin lining.
The one caveat, though, is that tin melts at 450 F, so don’t overdo the oven setting.
For The Washington Post