What Is Patina—and How Does It Differ From Rust and Tarnish?

When it comes to metal—be it a copper pan or an antique made from bronze—differentiating between a patina, tarnish, and rust can be tricky. While natural discoloration on these pieces is often highly sought after, other color changes are sometimes seen as an eyesore. Knowing the difference between a patina and rust can help you determine the condition your metal pieces are in—and make it easier to restore their luster.

Patina

Patina is the natural color that a metal will take on over time. "Patina doesn't flake on metal and is mainly just a color change, such as bronze turning green," says Eileen Fulton, a restorer for O'Sullivan Antiques in New York City. The term is commonly used in relation to copper or bronze pieces, and while it can be removed, many opt to leave the natural discoloration.

"Personally, when it comes to copper, I say let it take on its fullest character with the natural patina that its environment will determine," says Melissa Poepping, founder of The Chemical Free Home. "It truly is part of the beauty of bringing living metals into your home and décor."

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," says Jane Henry of Jane Henry Studios, a full-service antique conservation and restoration shop based in New York City. "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 noninvasive way to keep your pieces safe without making them look new."

How to Fake a Patina

If an antique doesn't have a natural patina, 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," says Henry. "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."

Tarnish

Tarnish is a 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," says Henry. "Tarnish is another form of corrosion that occurs in many metals other than steel—it typically causes a dull film on the metal."

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."

Rust

Unlike tarnish, rust is usually considered undesirable when it builds up on metal pieces. "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," says Fulton.

How to Identify Rust

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 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," says Henry.

How to Prevent Rust

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," says Shay Oron of Heirlooms Antiques & Art Additionally. Store 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," says Henry.

How to Remove Rust

Removing rust can be very difficult. "While the surface of more recently rusted objects can sometimes be flaked off, if it's been a while, you might be stuck with it," says Oron. "If a piece has rust for a long period of time, it can actually cause the metal to deteriorate and cause damage beyond repair." Light to moderate rust can usually be removed with lemon juice, but be sure to test a small hidden area first to ensure the cleaning method doesn’t damage the metal surface. Once you know it's safe, squeeze lemon juice over the damaged area then sprinkle with coarse salt and rub with a soft bristle brush. Then rinse with water and wipe dry.