After working as a chemist at a biotechnology company, I enjoy writing about science, travel, and gardening.
Silver Tarnished by Sulfur: Why It Happens
Silver is elegant and beautiful, but it also has a rather unsightly problem: tarnish. Silver tarnishes because it reacts with sulfur in the atmosphere and forms a compound called silver sulfide. Silver sulfide is black, and it's the ugly coating that develops over time on silver jewelry, dishes, and silverware. To prevent this problem, some silver items are coated with a very thin layer of another metal (often rhodium) to prevent the natural oxidation process when silver meets sulfur in the air.
The official chemical process for creating silver tarnish is:
H2S + 2Ag --> Ag2S + H2
Hydrogen sulfide gas makes contact with silver, creating silver sulfide tarnish and hydrogen gas.
Removing Silver Tarnish: The Chemistry
There are technically two ways to remove silver sulfide from silver objects. The first is through physical force - while this may be effective, it often damages the silver item and leaves ugly scratches on the surface.
A better method is to use chemistry to remove the silver sulfide from the object in question. Since the silver is oxidized, you need a reducing agent to return the blackened silver sulfide to shiny, metallic silver. Aluminum is a wonderful reducing agent and comes in the convenient (and affordable) form of aluminum foil. For those interested in the chemical reaction, the process is:
3Ag2S + 2Al --> 6Ag + Al2S3
Silver sulfide + aluminum reacts to form silver + aluminum sulfide.
Unfortunately, you cannot simply place a silver item on top of aluminum foil and add hot water to start the reduction process. Another agent is needed to help the chemical reaction along.
Since aluminum foil is coated with aluminum hydroxide, sodium bicarbonate is required to eliminate the film to expose the aluminum metal. Adding the sodium bicarbonate to the water also ionizes the solution, which helps speed the reduction process.
How to Clean Silver Tarnished by Sulfur
Cleaning silver requires a few items:
- Inert basin or bowl (i.e., a plastic or glass container or sink)
- Aluminum foil
- Sodium bicarbonate (also known as baking soda)
- Boiling water
Follow these steps:
- Add about a gallon of boiling (or very hot) water to the inert basin. In the images above, I used our plastic kitchen sink. Use plastic or glass as the reaction vessel: if you have a stainless steel sink, find another place to do your silver cleaning.
- Add one cup of baking soda to the hot water solution and stir until dissolved. Place a sheet of aluminum foil at the bottom of the sink. Place the silver object in the sink and wait for a few minutes as the tarnish begins to disappear.
- For very heavily tarnished items, the process may need to be repeated more than once.
- When the silver object is removed from the hot water bath, simply wipe the item with a dry, soft cloth. This will help to wipe off any excess tarnish sitting on the surface of the object.
The bowls were extremely tarnished in the images above and took two "baths" in the sodium bicarbonate/aluminum foil solution. After wiping with a dry cloth, the bowls were returned to a shiny, silver state.
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3 Cautionary Notes About Cleaning Silver
- Removing silver tarnish will eliminate the silver sulfide (black film) that develops on all silver objects, but it will not remove dirt or oil from the item. Wash your silver before removing the tarnish to get the best results.
- The aluminum foil/baking soda method works very well with silver. The higher the purity of the silver, the better the results will be. Unfortunately, this method does not work well with tarnished brass or copper - other methods are required for cleaning those oxidized metals.
- For highly valued silver coins, contact a professional prior to performing any cleaning: you do not want to devalue a rare coin by cleaning it the wrong way (or by cleaning it at all)! For very high-value items, let a professional do the work!
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
Questions & Answers
Question: Can the "silver basin" be washed and used for food storage or baking after being used for this process?
Answer: Yes, the basin may be washed and used for food storage after this process is complete.
Question: Would this tarnish remover process affect the diamond in my silver ring? Is it still advisable to do this?
Answer: This process should not affect the diamond in your ring in any way. If the ring is extremely valuable and antique, I would take the jewelry to a professional jeweler to have it cleaned.
Niveditha on July 28, 2020:
After black marks disappearance, for drying the silver item, we keep it outside for sometime, will it cause any black marks again?
Leah Lefler (author) from Western New York on March 07, 2018:
It really does work, RLaMarr! Of course, heavy tarnish will take more than one treatment. I have a silver-plated tureen given to me for my wedding and it becomes tarnished very easily. I have to treat it about twice per year, but it is maintaining its gleam!
RLaMarr on March 05, 2018:
I always wear a sterling silver chain, unfortunately I had a skin infection that required that I apply a sulfa ointment to my neck and chest. This caused my chain to become heavily tarnished. I've used this treatment twice and will need to do it again, but each time the tarnish has lessened so the treatment is working.
Taylor on November 22, 2017:
Found a lot of pins from Pinterest recommending this for tarnished silver costume jewelry. I was SO excited, followed the instructions to a tea. Unfortunately, every single piece of my jewelry is ruined. I have NO idea why? I'm so sad I'm searching Pinterest now to see if I can find another solution as my current wedding rings are also ruined (unfortunately lost my rings during pregnancy so wearing a pretend diamond for now)....Just would recommend using a test piece!!!!
Leah Lefler (author) from Western New York on August 06, 2013:
Yes - you would never want to remove the finish from a valuable antique. You could destroy its value! I have two silver dishes (modern dishes) that I clean myself - if I had anything of value, I would get a professional to do it. Excellent point, Weldon Jewellers.
Weldon Jewellers from Ireland on August 06, 2013:
great hub, and your point is well made about rare or antique pieces: never clean them unless you have received professional advice! it's very east to harm the patination and devalue the item.
Leah Lefler (author) from Western New York on July 01, 2012:
I only own a few silver items, Thelma (mostly silver plate, though some are pure silver). I was excited to discover this method of removing the tarnish, because it doesn't involve any toxic chemicals, and is pretty easy to do!
Thelma Alberts from Germany on July 01, 2012:
Eureka! Now I´ve found it! How to remove the tarnish out of my silver. I have been looking for the way I could get off the tarnish. I´ll apply this to my silver. Very well done. Thanks for sharing. Voted up and useful.
Leah Lefler (author) from Western New York on May 11, 2012:
It really works well, bellahurst. Just make sure the silver is in contact with the aluminum foil and use hot water. You may have to buff with a soft towel to get the residual tarnish off (it will be loose, but still on the dish). It is interesting to smell the sulfur as the solution does its work!
bellahurst from Australia on May 10, 2012:
Really useful. I really need an effective method to clean my silver stuff. Thanks for sharing this information.
Leah Lefler (author) from Western New York on April 27, 2012:
Thanks, friend! I don't own many silver things, but we do have the silver plated dishes and I own a very old silver baby spoon. It's an easy way to remove tarnish without scratching the silver!
hi friend from India on April 27, 2012:
very useful and informative
Leah Lefler (author) from Western New York on January 03, 2012:
Thanks, Peggy! It really does work - I have some jewelry that I need to clean up. I doubt I will get to it today, but it is a simple process to perform.
Peggy Woods from Houston, Texas on January 02, 2012:
I had heard about this a long time ago and had forgotten about it. Thanks for the reminder and explanation of why it works. Nice touch actually showing the process with your video. Voted up and useful.
Leah Lefler (author) from Western New York on January 01, 2012:
Thanks, Dirt Farmer! The method is really easy to employ, and completely non-toxic.
Jill Spencer from United States on January 01, 2012:
Very, very helpful! Vote up & useful.