Sterling silver is a popular metal used in jewelry, flatware, and other decorative items. Its affordability compared to pure silver and its attractive shine make it an appealing choice. However, sterling silver is prone to tarnishing and discoloration over time. Understanding what causes sterling silver to tarnish and how to prevent it can help you keep your sterling silver looking beautiful.
What is Sterling Silver?
Sterling silver is an alloy composed of 92.5% silver and 7.5% copper. The copper provides strength and durability to the relatively soft pure silver, while maintaining its attractive white color and shine. This combination of qualities makes sterling silver ideal for jewelry, cutlery, and ornamental items.
While sterling silver is more affordable than pure silver, it does require some care and maintenance. Pure silver is extremely resistant to tarnishing and oxidation. The copper content of sterling silver, however, causes it to gradually tarnish and darken with exposure to air and substances like sulfur.
What Causes Tarnishing?
There are a few key causes of tarnishing and discoloration in sterling silver:
- Sulfur – Sterling silver naturally reacts with sulfur compounds in the air. This causes a darkening effect called tarnish. Sources of sulfur include air pollution, rubber bands, wood, felt, and more.
- Oxygen – Extended exposure to oxygen in the air can cause oxidation leading to tarnishing.
- Salt and Acids – Salt, food acids, skin oils and lotions can react with sterling silver causing corrosion and pitting.
- Impact – Repeated impacts and abrasion over time degrades the surface leading to a loss of shine and luster.
- High Temperatures – Exposure to high heat can accelerate tarnishing and chemical reactions.
Does Sterling Silver Tarnish?
Yes, sterling silver does naturally tarnish over time when exposed to air and common sulfur compounds. Tarnish appears as a dark, muted gray or black coating on the surface of sterling silver items. It is caused by a reaction between the small amount of copper in sterling silver and the sulfur gases present in the atmosphere.
Sterling silver tarnishes faster than pure silver because pure silver is more resistant to tarnishing. Even high quality sterling silver will gradually tarnish with regular use and exposure to air. The rate of tarnishing depends on factors like air quality, storage, and care.
Tarnishing Process
Here is an overview of the chemical process of how sterling silver tarnishes:
- Sulfur compounds in the air interact with the copper content in sterling silver
- This interaction causes copper sulfide deposits to form on the surface
- The copper sulfide coating results in a dark “tarnished” appearance
While unsightly, tarnish only affects the very surface layer of sterling silver and does not damage the underlying material or cause deterioration. It can be easily removed through polishing and buffing.
What Causes Discoloration?
In addition to tarnishing, sterling silver can develop other types of unsightly discoloration over time. Common causes include:
- Oxidation – Air exposure over time triggers an oxidation reaction, causing a buildup of black silver oxide coating.
- Firescale – A dark discoloration caused by heat during soldering and other metalwork. Composed of copper oxide.
- Corrosion – Prolonged contact with salt, lotion, or skin oils can “eat away” at the silver, causing pitting.
- Denting/Scratches – Repeated impacts create small dents and abrasions that reduces shine.
While less common than regular tarnish, these forms of discoloration and damage need to be repaired by a professional jeweler or silversmith in some cases.
Does Sterling Silver Change Color?
Sterling silver does not normally change color outside of tarnishing to a darker, muted shade. However, there are a few circumstances where the color of sterling silver may alter:
- Patina – A patina is a thin darkened layer that gradually develops on sterling silver surfaces from extended handling and wear. This can impart an vintage, antique look.
- Oxidation – As oxidation increases over years, the black silver oxide layer becomes more prominent and may permanently color the metal.
- Extreme Tarnish – If allowed to tarnish for extremely long periods, sterling silver can develop very thick layers of black, blue, or purple tarnish that act as new colored surface.
- Alloy Mixing – If sterling silver is melted down and re-worked multiple times, uneven mixing can cause color variations throughout the material.
Aside from these scenarios, the underlying bright white color of sterling silver does not typically change, fade, or alter. Proper maintenance and care keeps it looking its best.
How to Prevent Tarnishing
While some tarnishing is inevitable, you can help prevent or delay it by:
- Storing in air-tight containers to limit sulfur exposure
- Using anti-tarnish strips and cloths in storage containers
- Avoiding contact with rubber, felt, wood, and paper
- Cleaning regularly with a sterling silver polish
- Applying a thin lacquer coating for very long-term storage (years)
Taking steps to limit air, sulfur, and chemical exposure will help slow the tarnishing process and extend the beautiful shine and luster of your sterling silver items.
How to Clean Tarnished Sterling Silver
There are a variety of effective methods for cleaning tarnished sterling silver:
Silver Polishing Cloth
Specialized cloths impregnated with mild abrasives easily remove light tarnish. Gentle rub the cloth over the sterling silver surface to restore shine and luster. Works well for maintenance cleaning.
Silver Dip
Chemical dips quickly dissolve heavy tarnish for a deeper clean. Submerge or soak sterling silver pieces for 1-3 minutes. Rinse and dry thoroughly afterwards.
Baking Soda and Aluminum Foil
A homemade approach using baking soda and aluminum foil. The chemical reaction helps lift tarnish. Line a pan with aluminum foil, coat with baking soda, place silver pieces in, and heat 250°F for 1-2 hours.
Silver Polish Paste
Polishing pastes contain mild abrasives to effectively buff away tarnish buildup. Apply paste with soft cloth and rub gently in direction of any engraved patterns.
Ultrasonic Cleaner
Uses ultrasonic waves and solution to deeply clean silver. Especially effective for cleaning in engraved areas and crevices.
Electrolysis
Uses an electric current in a chemical bath to reverse the tarnishing process and remove discoloration. Typically used by professional jewelers and silver repair shops.
Always avoid immersing sterling silver pieces with gemstones in cleaning solutions. It’s best to have jewelry professionally cleaned to avoid potential damage.
Does Sterling Silver Permanently Tarnish?
No, sterling silver tarnish does not permanently ruin the metal. Tarnish only affects the very top layer of atoms on the surface. It can be removed through regular polishing and buffing to restore the original pristine shine and brilliance.
No matter how dark and discolored sterling silver becomes from tarnish buildup, the metal underneath remains undamaged. With the proper cleaning method even very old, heavily tarnished antique and vintage silver can be revived to look as good as new.
To prevent permanent damage, be sure to periodically clean and polish your sterling silver. Letting tarnish accumulate for too long can make removal more difficult. With ongoing care, sterling silver will maintain its beauty and luster for many years of enjoyment.
Does Sterling Silver Tarnish Faster Than Pure Silver?
Yes, sterling silver tarnishes significantly faster than pure silver. There are two key reasons for this:
- Copper Content – The 7.5% copper mixed into sterling silver readily reacts with sulfur to form tarnish. Pure silver has no copper to react.
- Purity – The higher purity of fine silver makes it more resistant to chemical reactions like tarnishing.
Silver naturally has anti-bacterial and anti-tarnish properties. By diluting the purity to 92.5% in sterling silver, these properties are reduced allowing more chemical reactivity with the environment.
Here is a comparison of how fast different silver alloys tarnish:
| Silver Type | Purity | Tarnish Resistance |
|---|---|---|
| Fine silver | 99.9% | Excellent |
| Britannia silver | 95.8% | Very Good |
| Sterling silver | 92.5% | Moderate |
| Coin silver | 90% | Fair |
So while sterling silver tarnishes faster than purer silver alloys, it provides the best balance of affordability, durability, and resistance for most applications. With proper care it can still retain its shine and luster for many years.
Does Sterling Silver Tarnish in Water?
Sterling silver alone does not normally tarnish in pure water. However, sterling silver jewelry and items can still gradually tarnish and discolor when exposed to water over time. The factors that contribute to water-related tarnishing include:
- Impurities in the water like chlorine and minerals
- Soap, shampoo, and other residues left on the metal
- Saltwater accelerating corrosion and pitting
- Stagnant or polluted water allowing buildup on the surface
These aspects introduce new chemicals, dirt, oxidation, and opportunities for gradual damage from prolonged exposure. Therefore, sterling silver is best kept away from water outside of quick cleaning and rinsing.
To help prevent water-related tarnishing of sterling silver jewelry:
- Avoid wearing in baths, pools, saunas and hot tubs
- Take off sterling silver jewelry before showering, bathing, cleaning, etc.
- Thoroughly dry sterling silver pieces after any contact with water
- Store sterling silver in a cool, dry place away from humidity
With some care, sterling silver can maintain its shine and appearance while still being worn and enjoyed regularly.
Does Sterling Silver Tarnish in Sunlight?
Direct sunlight does not cause sterling silver to tarnish. In fact, a small amount of UV exposure can help keep sterling silver clean and bright by inhibiting bacteria growth.
However, there are a few indirect ways that sunlight can contribute to tarnishing over time:
- UV rays accelerating oxidation of the metal surface
- Heat from sunlight increasing tarnish-promoting chemical reactions
- Discoloration of surface residues and dirt under sunlight
Silver itself does not react with sunlight energy and solar radiation like other metals. But the warming effects of UV and infrared light can indirectly worsen tarnishing from heat and oxidation.
To minimize sunlight-influenced tarnishing:
- Avoid leaving sterling silver unattended in direct sunlight for very long periods
- Clean and polish sterling silver regularly to remove oxidation and residues
- Store in cool, dry places away from sources of heat and light
With basic care, sterling silver can be enjoyed outdoors and in daylight without significant tarnish or color change in most cases.
How to Store Sterling Silver
Proper storage is key to keeping sterling silver tarnish-free. Here are some tips for ideal sterling silver storage:
- Use air-tight containers or bags to limit air and sulfur exposure
- Place pieces individually in anti-tarnish cloth bags or acid-free tissue.
- Include desiccant packs or oxygen absorbers to maintain a moisture and oxygen-free environment.
- Avoid paper, wood, rubber bands, and other sulfur-containing materials in the storage container.
- Store in cool 60-70°F temperature away from heat sources.
- Keep pieces dry and avoid humidity which accelerates tarnish.
- Clean and polish silver before long-term storage for added protection.
With proper storage and care, sterling silver pieces can maintain their like-new quality and appearance for many years before ever needing to be polished.
Conclusion
Sterling silver is prone to gradual tarnishing when exposed to air, sulfur, and humidity over time. But it does not permanently change color or become damaged underneath the tarnished surface layer. Regular cleaning and careful storage can help minimize tarnish buildup and keep sterling silver looking its best. With the proper care, sterling silver maintains its beauty and is a classic, timeless metal to enjoy for generations.
