You may notice that over time your silver jewellery will change colour. The first thing you’ll observe is a yellowish tinge, which may change to a subtle purple colour before eventually turning black.
What you’re observing is a process known as tarnishing, a natural and inevitable chemical reaction between the silver and other chemicals in close proximity. Thankfully, tarnish can be easily removed from silver, restoring it to its original white luster.

The Causes of Tarnishing

There are a number of chemicals that will react with silver to cause tarnish, and by far the most common culprit is sulfur, which is present in many forms around us. Hydrogen sulfide (H2S) and sulfur dioxide (SO2) exist in the air around us, particularly in urban or industrial areas (and volcanoes!). Hydrogen sulfide, which is known for its “rotting egg” odor when it occurs in high concentrations, reacts with silver to form silver sulfide, the substance that tarnish is made of. Even when hydrogen sulfide occurs in low concentrations, this chemical reaction can occur.

There are many other possible points of contact with sulfur in daily life. Bore-water, for example, can be very high in sulfates or sulfides. Many soaps, facial cleansers, shampoos, detergents, perfumes and foods, such as onions and eggs, also contain sulfur compounds. So, washing in sulfur-rich water or using skin products, soaps or detergents made with sulfur can all lead to the quick tarnishing of silver. Even eating foods containing sulfur may cause silver to blacken, as the sulfur is secreted through the skin in perspiration.

Another factor that will accelerate tarnishing in silver is the presence of moisture in the air. In fact, in dry air, silver will not tarnish. The higher the level of humidity, the faster the rate of tarnish. This is further compounded in warm conditions.

Other than sulfur, another common chemical that will react with silver is chlorine. Pool water, the air around an indoor pool, bleaches and fabrics washed with bleach will all contain traces of chlorine, which will react with silver to produce a black layer of silver chloride.

Sterling silver is usually a mixture of silver with a little bit of copper. The copper content itself will also tarnish through the process of oxidation. Copper reacts with oxygen to form black copper oxide. This may also blacken the surface of your silver.

Various acids will also cause silver to tarnish. People often report that when their silver is wrapped in tissue it quickly blackens. This is because tissue paper often contains acids. Another consideration is the acidity levels of the skin. Some people report silver blackening on them overnight, whereas others can wear it for years without a reaction. Different skin PH levels will result in different rates of tarnish.

In a nutshell, there are many things in daily life that can cause your silver to tarnish, and the speed at which it tarnishes will vary depending on the specific conditions: the sulfur content of the water in your area, the amount of industrial pollution, the chemicals you’re exposed to at home or work, including detergents, shampoos and soaps, some skin cleansers, foods…the list goes on.

Removing Tarnish

There are dips, cloths and other techniques for removing tarnish from the surface of silver.

Polishing Cloths

Perhaps the simplest method is to use a microfiber silver polishing cloth, available from most jewellers or jeweller supply shops. These are usually impregnated with a silver-polishing compound, and are a must for any silver jewellery owner. Simply rub the silver surface with the cloth by hand to remove the layer of tarnish and bring the jewellery back to its original shine – you’ll notice that the cloth itself will be covered with black residue – this is the tarnish you’ve just removed from the silver. This method is very good for maintaining clean silver, but may be hard work for heavily tarnished pieces. What’s more, if the silver is somehow textured, it won’t be able to remove all of the tarnish. Brushed silver, for example, has many tiny grooves, which are inaccessible to a cloth

Chemical Cleaners

An alternative is to use silver polish paste or liquid. The paste is rubbed on the silver piece, or the silver item is immersed in the liquid. The drawback of both of these methods is that they’re a bit fiddly and messy, and they potentially expose you to unpleasant chemicals.

Ionic Cleaner

A very effective and safe method is to use an ionic cleaner, which uses the process of electrolysis. Some jeweller supply shops carry these electrolysis kits specifically for the purpose of cleaning silver. Two electrodes, one with a silver point on it and the other with a stainless steel one, are attached to a battery pack and immersed in a solution of pure water mixed with an electrolyte powder, along with the item to be cleaned. Within seconds, traces of tarnish disappear. (Note that with  jewellery that has an intentionally oxidized or painted black surface, immersing for too long will remove all traces of black). After cleaning, rinse in water. We recommend finishing off this process by rinsing your jewellery piece in a bowl of warm water and alcohol (you can use methylated spirits). This will cause the water to bead, and your jewellery piece will dry almost immediately.

A Home-made Method

If you want to try something homemade, line the bottom of a clean glass or plastic container with aluminum foil. Combine hot water with 2 teaspoons of baking soda and 1 teaspoon of salt and add to the container. Immerse your jewellery, making sure that it’s in contact with the foil. An electrolytic chemical reaction will occur, transferring the tarnish from your jewellery to the foil (Beware with stones in boiling hot water. Some may crack!).

Slowing Down the Tarnishing Process

Though it may be impossible to totally prevent the natural occurrence of tarnish, there are things you can do to slow down the process considerably.

Put your jewellery on, only after applying perfume, deodorant, aftershave or cologne – not before. Avoid wearing silver when swimming, as chlorine and seawater will both react with it. Avoid exposure to household or industrial cleaning chemicals when possible.

When removing your silver jewellery, ensure it is dry and wipe with a silver polishing cloth. Store your jewellery wrapped in a cloth or in a sealed plastic bag and keep in a dry place – the bathroom is not a suitable storage environment. In jewellery boxes or cabinets, you can use silica gel to remove excess moisture. Be aware that jewellery in cabinets that are in direct sunlight will usually tarnish faster, because heat speeds up the chemical reaction. Don’t wrap your stored jewellery in tissue paper or in contact with rubber, unless you can confirm these are acid free.

If you believe your jewellery requires some cleaning before storage, you can wash it in a mixture of warm water (not hot) and a gentle detergent (phosphate free), using a soft cloth or a brush with soft bristles. Dish washing liquid is suitable, but NOT for pearls! Ensure that you use a soft, non-abrasive cloth or brush, as silver is a soft metal and prone to scratching. With purposefully oxidized surfaces,  be mindful of not brushing out the black oxidation.

Ensure your silver is dry before storing.

Above all, monitor your silver jewellery, and be prepared to regularly polish or clean it with any or a combination of the methods described above.
The reward? The beautiful white light of sterling silver revealed!