What's the Difference Between a Patina Finish and Tarnish?
Let's face it: When it comes to antiques, differentiating between a patina and tarnish can be tricky. "Rust is one form of patina. It is the result of corroding steel after the iron particles have been exposed to oxygen and moisture, like humidity, vapor, or immersion," explains Jane Henry of Jane Henry Studios, a full-service antique conservation and restoration shop based in New York City. "Tarnish is another form of corrosion that occurs in many metals other than steel, it typically causes a dull film on the metal."
How can you determine whether or not a patina is rust, tarnish, or simply an age-induced finish? "Patina doesn't flake on metal and is mainly just a color change, such as bronze turning green," explains Eileen Fulton, a restorer for O'Sullivan Antiques in New York City. "Rust is an iron oxide usually red in color and usually on iron only, while tarnish is a thin layer and is often black or grey and it's on many different metals."
How to spot and remove rust.
Henry says that when iron or steel is exposed to water, the iron particles are lost to the water's acidic electrolytes, which in turn causes rust. "It appears in orange with a flaky texture, and is generally considered an eyesore, but in the right circumstances can give an object a look of age and authenticity," she explains. While the surface of more recently rusted objects can sometimes be flaked off, Shay Oron of Heirlooms Antiques & Art says that if it's been a while, you might be stuck with it. "It is very difficult to remove rust," she says. "If a piece has rust for a long period of time, it can actually cause the metal to deteriorate and cause damage beyond repair."
How to prevent rust in the first place.
According to Oron, a steel or iron item that is painted or oiled will take longer to develop rust. "Less exposure to the elements will prevent both tarnish and rust," she explains. Additionally, Henry suggests storing your precious steel and iron pieces in a cool, dry place, to safeguard them from moisture. "To avoid rust and tarnish, keeping metal dry and storing it properly is key," she says.
Be cautious when polishing tarnished pieces.
While rust is usually considered an eyesore, Oron says tarnish on metals is often highly sought-after, which is why you should be careful when polishing. "Some silver or bronze decorations should never be polished to a high luster as it will decrease the antique's value. It is always better to err on the side of caution and consult a reputable dealer before polishing any antique items. Because good patina takes many years of exposure to build up, it is very important to preserve it."
How to preserve a patina.
A little wax or lacquer can go a long way in preserving the patina of an antique object. "Don't heavily clean any desirable patina," Henry says. "For metal, a coat of lacquer can prevent corrosion, and also can seal in the patina. For patina on wood, a protective layer of wax is a handy non-invasive way to keep your pieces safe without making them look new."
How to fake a patina.
Good news: If an antique doesn't have a natural patina, Henry says you can try to apply a faux finish. "In some cases, whether an object is an antique or a new piece, an applied patina can be added to create a desirable effect," she explains. "There are commercial solutions that can be purchased to help speed up the oxidation process on metals, and certain wood glazes can add the look of years of hand oils and wear."