A reader wants to know what to do about corrosion on a brushed nickel faucet. (Reader photo)

Q: I have a brushed nickel kitchen faucet that has developed blemishes over the years. What causes these? Can they be removed? Is there any way to prevent them from happening if I were to obtain a new faucet?

Herndon

A: Corrosion is relatively easy to prevent. But it can be difficult or even impossible to undo. The cause is usually improper cleaning — either too much (by using harsh chemicals or abrasives) or too little (by leaving spatters of acids or other harmful ingredients on the metal until all the moisture evaporates).

“Many fibrous pads or sponges contain microscopic mineral particles that can scratch a faucet’s finish,” Gary Parobek, part of the customer quality improvement group for Moen (800-289-6636; moen.com), said in an email. “In addition, cleaners that contain abrasives, harsh chemicals, alcohol or other organic solvents can cause damage and corrosion.”

On a bathroom faucet, besides cleaner residue, you also have to worry about spatter from toothpaste, acne medicine and mouthwash. These often contain ingredients such as baking soda, peroxide, sodium fluoride or phosphates, which can damage faucet finishes when they are left in contact with the metal for long periods.

Leaving cleaners or other spatter to evaporate on a faucet increases the risk of corrosion because the concentration of the cleaning chemicals increases as the water disappears. “Damage depends on contact time and concentration,” Parobek said.

That’s why his key advice is to wash faucets with mild soap, rinse thoroughly with warm water and dry with a soft, clean cloth. (Non-creamy hand dishwashing liquid, such as Dawn, works well.) To remove mineral deposits, Parobek recommends using a half-and-half solution of vinegar and water, followed by a thorough rinsing and then drying with a soft cloth. However, some faucet finishes can be damaged by any acidic cleaner, so if you know the brand and model of your faucet, read the manufacturer’s care instructions first.

For extra protection, Parobek recommends an occasional final step: “Just as a car can be waxed to protect its finish from damage, consumers can use an automotive wax to protect the finish of their faucet.”

If a faucet is already corroded, it’s sometimes possible to rub the tarnish away by using an automotive cleaner and polish. Parobek recommends Flitz Metal, Plastic & Fiberglass Polish ($12.25 for a 1.76-ounce tube at flitz.com).

Brushed nickel finishes, which are rubbed with an abrasive while still at the factory to create their special look, are especially susceptible to damage from bathroom and kitchen cleaners that contain low-concentration phosphoric acid. If not rinsed promptly, these can damage or even remove a brushed nickel finish. “Flitz will clean and protect the surface,” Parobek said.

Whatever the finish, if black spots remain after you use the metal polish, there is little else to try. Although a plating shop can redo a finish such as chrome, the most practical option is to get a new faucet.

If you opt for a new faucet, ones that are solid brass underneath are more durable than ones made of die-cast zinc or plastic.

Over the faucet body, the most corrosion-resistant finishes are applied via a process called PVD, for physical vapor deposition. The parts go into a vacuum chamber where an electrical charge is used to attract minute bits of finish to the faucet base. This results in an extremely durable bond that manufacturers often claim will last a lifetime. Moen calls these LifeShine finishes. Delta’s term is Brilliance. Kohler’s is Vibrant. Options include brushed or polished nickel, satin or polished brass, and new colors that a manufacturer might call Carbon or Graphite.

The key thing to realize is that although PVD finishes aren’t likely to peel, harsh chemicals or abrasives can still damage them. Read the warranties and you’ll see that the lifetime guarantee is void if you use almost anything other than warm, soapy water as a cleaner. But if you stick to that, the results can be excellent.

Besides PVD finishes, you can also find faucets with powder-coat finishes and metallic finishes that have a clear protective topcoat. These are even easier to damage with abrasives or harsh chemicals. Trickiest of all are “living finishes” that are designed to wear and age over time, creating a patina look. These have no protective coating, so it’s easy to scratch or wear through the finish.