Have you ever heard of boiling silver coins in water/baking soda?

Longacre

I have never heard of this technique, although I have heard of gold coins being baking-soda’d. I read this in the Canadian Numismatic Association’s E-Bulletin. I would never clean coins, but I was curious if anyone has used this technique or heard of it. Can any of the chemistry majors comment on the chemical activity and why it works (but please don’t write any of those crazy chemical symbol matrixes).

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[A reader] received a tip from a friend about cleaning coins: “Heat a pot of water to near boiling, dissolve baking soda (sodium bicarbonate) and a pinch of salt (salt is optional) into the water. Put a sheet of aluminum into the water. Lower the silver item(s) into the water onto the aluminum sheet. Contact with aluminum is crucial as this allows the chemical process to occur. When bubbles cease to be formed off the silver, retrieve the silver and pat dry. You may want to rinse the silver under running water to clean the baking soda off. If you Google ‘silver cleaning with aluminum and sodium bicarbonate,’ you should have lots of hits.” [The reader] commented that he thought the salt would have created a chemical activity on its own. Would our chemical experts please comment?

StrikeOutXXX

I use it all the time with metal detecting finds. Works pretty good too. Only difference is, the recipe I originally found is Arm and Hammer Washing Soda (Oxy Clean is a close 2nd), not actual baking soda.

Here is a good link:
Arm & Hammer Method

pendragon1998

Well, it's been a few years since my last chem class, but here's what I think's going on:

You're creating a simple electrolytic reaction when you place the two metals (aluminum and silver) in an electrolyte bath (baking soda in water disassociates to basically make a sort of salt water solution. This is the same general principle as a simple battery. Electrons flow from one metal to another and, long story short, the tarnished silver sulfide ions transfer onto the aluminum, making the silver look nice and clean again. Boiling the water is done to add heat (energy) to speed up the reaction. The reaction doesn't require the silver to contact the aluminum, and indeed, if it was a coin providing the silver, you'd risk scratching it on the aluminum. Simply having both metals in contact with the solution suffices. This process will remove metal from the coin (fairly slowly) so consider it as being like a dip.

Baking soda (sodium bicarbonate) is usually used for this, but just about any other salt (even table salt) would work with varying degrees of effectiveness.

Cladiator

<< <i>I read this in the Canadian Numismatic Association’s E-Bulletin. >>

All hope is lost for you my friend.

ccr

I`ve done it before. I`m not an expert on chemistry but, the results I got I wouldn`t try it on really valueable silver. The toning/tarnish ( for silverware buffs ) goes away after boiling and wiping with a cloth. It does strip, or at least greatly inhibits, the luster as well. So don`t try it on really valuable items unless you`re willing to see the luster go away too. But, it really does take away the toning/tarnish fairly well.


PS - The basic battery is copper and silver layers with a water/salt mix. Copper is part of the reason it works for coins and sterling silver.

mgoodm3

I would think that you would make a buffered carbonic acid solution.

ccr

<< <i>I would think that you would make a buffered carbonic acid solution. >>



I wouldn`t really know to be honest. It has been years since I tried it on a Silver Eagle and some silverware.

Maybe I tried to much baking soda but, used a spoonful of it on the Silver Eagle. I put the boiling water into a cup with the aluminum foil, baking soda, and the Silver Eagle and it bubbled for awhile like what you see in a glass of soda pop. After it was done bubbling, I took it out and it had a film of baking soda and much of the toning gone.

Bear

Would being boiled in a backing soda

solution, remove the grime from a coin collector?

ccr

Let`s try it on some coin dealers and see what happens.

DieClash

I tried on some circulated coins with alot of ugly dark toning. I had mixed results. On average the coins looked better, but not much. I also noticed that I had to rebuild the bath after only a few coins. I had worse results with multiple coins in the same time.

I cleaned about 6 silver dollars and 7 dimes with the experiement and then gave up.

I would definitely not recommend it with valuable collectibles.

Perhaps if I used a glass to pour the boiling water in instead of a stainless steel pot and distilled water instead of tap water I might have had better results.

SanctionII

When I was 7 or 8 years old and collecting pocket change I would clean silver coins with baking soda and water. I would wet the baking soda with water, make a paste and rub the coin with the paste in between my fingers.

At the time I liked the way the coins got all nice and shiney. Since then I have learned differently.

clarkbar04

Here's my recipe:

1 morgan dollar
2 c of water
1 tsp of baking soda
1 cup of flour

boil dollar, water and baking soda, mix with flour; add cholate chips to taste

11-15 min @ 350. Cookies will be hard in center.