Cleaning silver - the science behind it?

Just caught a piece on the TV about cleaning silver. Went like this:
about a tablespoon each of salt and "water softener" (Probably meaning
Calgon or similar?) per quart of hot-as-you-can-stand water, well mixed,
then sink a piece of standard aluminum foil in your container - any type.
Now take any tarnished silver you want cleaned up, and dunk it, making
certain to make contact with the foil. The demo I caught used a nearly
black teapot. The demonstrater dunked it, swished it around while
counting seconds, and at five, pulled it out. Everywhere the
salt/softener solution touched looked like it had been polished on a
buffer wheel.
OK, what's the secret? Obviously, it's an electrolytic reaction going
on, but I'm not seeing which one. What's in water softener to make it
happen? Anybody got the scoop?
Reply to
Don Bruder
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From a site presented by the Society of American Silversmiths:
"Electrochemical (Galvanic) Reduction
"This process uses an aluminum or aluminum alloy plate and warm solution of sodium carbonate (washing soda). When the object comes in contact with the plate in the solution, it removes only light tarnish, not the thick, black tarnish produced by years of neglect.
"Pitting of the object can occur if the aluminum plate is not periodically cleaned. Another not-so-obvious problem is scratching of the object when in contact with the plate.
"Objects cleaned by this method may tarnish more quickly than silver that has been polished, for the object's surface will act like a sponge and more readily absorb tarnish-producing gases and moisture. The solution can also seep into hollow areas such as coffee pot handles, unsoldered spun beads around the tops of lightweight holloware, weighted pieces with minute holes, and any porous attachments. For these reasons, this cleaning technique is not recommended."
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Reply to
John Ings
You can also use baking soda or an other mild alkali with the foil, I use Sulfamic Acid as a quick dip to clean the copper parts in the induction furnace, I noticed it is the active ingredient in "Tarnex" Alan Black
Reply to
Alan Black
Silver tarnish is silver sulfide. The sodium carbonate is a basic electrolyte which lets it penetrate the oxide layer on the aluminum to reach fresh aluminum metal which is more electrochemically active than silver. The aluminum oxidizes while the silver reduces to silver metal, so you wind up with aluminum sulfide. The silver deposit is usually a little rougher than the silver surface, so manual polishing really helps to make it look its best. If you just polished the tarnish away you would lose that silver, so this puts it back on the surface, and for mildly tarnished stuff it can look plenty good enough to skip the polishing totally. Really ugly, pitted silver will need lots of elbow grease after the electochemical cleanup.
-- Regards, Carl Ijames carl.ijames at verizon.net
21, 2004.
Reply to
Carl Ijames
This is not exactly the same thing, but close enough to possibly add to the topic. I have a very old, in the original box, "Maggie Pan," for cleaning silver. The pan is said to be magnesium, and instructions are to use "any detergent."
Reply to
Leo Lichtman
The secret is the aluminum. You can use sodium bicarbonate and water instead of the water softener.
Reply to
Unknown
As others have said, this is an electrolytic reduction of the silver compounds making up the tarnish. You're making a short-circuited electrochemical cell. The salt acts as an electrolyte(but I wouldn't use it) and the water softener probably keeps the calcium in hard water from interfering. Most of those products also have some sort of detergent in them, which would help with wetting the surfaces. The reason I wouldn't use salt is that it'll attack silver all by itself, chloride just loves to combine with silver.
We've used this method for many years in my family, my folks and relatives have some "Dowmetal" griddles that were purchased shortly after WWII. These are largely magnesium and work for this quite well. They're just small enough to sit on the bottom of the kitchen sink. A little squirt of detergent and a couple hours immersion usually brightens up the silverware to the point that it doesn't need further polishing. I've never heard of aluminum being used, but any metal more active than silver could be used as the other plate of the cell. There have been some magnesium-containing products sold over the years to do the same thing, some at very fancy prices. You will occasionally find these griddles at rummage and garage sales for fifty cents or so, they're worth grabbing. They also work very well as griddles. They look like aluminum, but the weight and the "Dowmetal" stamp gives them away.
Stan
Reply to
Stan Schaefer
Note that it says detergent, not soap. Gerry :-)} London, Canada
Reply to
Gerald Miller
Soaps are usually detergents (so is sand , in the right circumstances:-)
Mark Rand RTFM
Reply to
Mark Rand

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