An original brass faucet, left alone. The colour in that metal took eighty years to arrive and about ninety seconds to destroy.
There is a particular sound I have learned to dread in an old house, and it is the sound of someone opening a tin of metal polish.
Brass and copper fixtures in a period home are not hardware. They are the closest thing a bathroom has to an heirloom. The colour on them, that deep, slightly uneven brown-gold that shifts depending on where the light falls, is patina, and it is the single hardest finish to fake. Manufacturers have spent decades trying. You can buy a brand new faucet sold as "aged brass" and it will still read as new, because what it is imitating is time, and time does not photograph well enough to copy.
So here is my position, stated plainly. If you have inherited original brass or copper in a house, your job is to clean it, not to restore it. Those are two different projects and only one of them is reversible.
What patina actually is, and why stripping it is a mistake
Patina is oxidation. Brass and copper react with air and moisture over years, and the surface layer that forms sits on top of the raw metal like a skin. That skin is doing real work: it slows further corrosion, and it is the reason a hundred-year-old fixture is often in better condition than a twenty-year-old one.
It is also the whole point aesthetically. Old things look better with new things next to them, and a patinated faucet against fresh plaster and a crisp marble slab is exactly that contrast. Strip it back to mirror-bright and you have flattened the room into one note. The fixture stops being the oldest thing in the space and starts being just another shiny object, competing with the taps in every other bathroom built since 2015.
This is the same argument I make about mixing modern and vintage generally. Contrast and intention tell a much more compelling story than things that match perfectly. Patina is contrast you did not have to buy.
The four things that destroy it
Commercial metal polish
Brasso and everything like it is formulated to take brass back to bare metal. That is its stated job. It contains fine abrasives and ammonia, and it does not distinguish between tarnish you want gone and patina you want kept. One pass, and decades are on the cloth.
Anything abrasive
Steel wool, wire brushes, green scouring pads. Brass is soft and copper is softer. The scratches these leave do not buff out, and they cut through the oxidised layer that gives the surface its depth. What is left reads flat and slightly grey, which is somehow worse than shiny.
Power tools
Sandblasting and buffing wheels are for architectural salvage that has already been ruined. On a working Victorian fixture, a buffing wheel produces a chrome-like glare that is completely wrong for the period and impossible to undo. Sandblasting will simply eat softer copper.
Confusing verdigris with patina
This one catches people out. The powdery green bloom on copper is verdigris, and it is not the same thing as a stable patina. Verdigris is active corrosion, it is soft, it comes off on your hand, and left alone it keeps eating. Green needs to be dealt with. Brown does not.
How to clean brass and copper properly
The technique is unglamorous, which is why so few people do it.
Start with soap and water. Warm water, a few drops of mild dish soap, a lint-free microfibre cloth, and a soft natural-bristle brush for the crevices and the base of the spout where grime collects. Wipe, rinse with clean water, dry immediately. Nine times out of ten this is the entire job. Most of what people read as tarnish is soap scum, hand oil and limescale sitting on top of a perfectly good patina.
For grime that will not shift, use lemon and salt. Halve a lemon, sprinkle salt on the cut face, and work it gently over the stubborn area. The citric acid lifts deposits. It also, given time, lifts patina, so this is a thirty-second job followed by an immediate rinse in cool water and a dry cloth. Do not let it sit. Do not use it as a general clean.
For verdigris, go local and go small. A paste of bicarbonate of soda and water, applied only to the green with a cotton bud, left ten minutes, then wiped off and rinsed. Working with a cotton bud rather than a cloth is the whole trick, it keeps the treatment on the corrosion and off the surrounding finish.
Test everything on the least visible part of the fixture first. The underside of a spout, the back of an escutcheon. Metals from different decades behave differently and lacquered pieces behave differently again.
Sealing, so you only do this once
Cleaning without sealing means repeating this in four months, and every repeat costs you a little more patina.
For most fixtures, use a microcrystalline wax. Renaissance Wax is the one museum conservators reach for, which tells you something about how it behaves on objects nobody is allowed to replace. A thin coat applied with a soft cloth in small circles, left about fifteen minutes, buffed lightly. It leaves a barrier against oxidation and skin oils without adding gloss.
Faucet handles and anything else touched several times a day will wear through wax. Those are the candidates for a clear metal lacquer instead. It is fussier to apply and it has to go onto a scrupulously clean, completely dry surface or it will cloud, but it lasts years rather than months.
Whichever you choose, humidity is the variable nobody accounts for. A bathroom that swings between steam and dry air will age metal, wood and textiles faster than the same room kept steady. Humidity decides how your materials age, and brass is no exception.
When it stops being a cleaning job
There is a line, and it is worth naming, because the expensive mistakes happen just past it.
Call someone in when the fixture has to come off the wall or out of the floor, when the internal workings have failed and the piece needs to function rather than just look right, when several original pieces need to be brought to a matching finish, or when the house carries a historic designation with rules attached. In a pre-war building especially, this is worth doing properly the first time. A good old-school plumber in Manhattan who works in brownstones regularly will keep the original fixture in service rather than reaching for a modern reproduction, and will know how to have a period-appropriate replacement part fabricated when something is genuinely beyond saving. That knowledge is the difference between a bathroom that reads as original and one that reads as a renovation.
The same logic applies to the rest of the room. If you are working through a period bathroom properly, the fittings and the light are a package. I have written separately about how to approach a bathroom as a whole, and about choosing fixtures for low ceilings, which older houses have in abundance.
The short version
Clean, do not restore. Soap and water first, always. Nothing abrasive, nothing marketed as a polish, nothing with a motor. Treat green as corrosion and brown as an asset. Seal with wax, or lacquer if the piece gets handled daily. And when the job moves from surface to structure, hand it over.
These fixtures were built to last centuries, which they will, provided nobody decides to make them look new.
