Brass burners, galleries and fittings are half the reason people like oil lamps, and they are also where enthusiasm does the most damage. Metal polish is quick, satisfying and irreversible, and a great many old lamps have been scoured down to a bright, characterless shine that will never come back.

Lacquered or bare: find out first

Much modern brass is lacquered to keep it bright. Polish applied over lacquer does nothing except cloud and streak it, and abrasive polish takes the lacquer off in patches, after which the metal tarnishes unevenly. If a fitting is uniformly bright and shows no tarnish at all after a year, assume it is lacquered and clean it with nothing more than a damp cloth.

Bare brass and the case for patina

Unlacquered brass darkens over time into a warm, uneven colour that most people find far more attractive on a lamp than a mirror finish. On older lamps that patina also carries whatever value the piece has. Cleaning it back to bright is a decision, not maintenance, and it cannot be undone.

What actually needs cleaning

The parts that matter functionally are the burner air holes, the wick slot and the threads, and they need soot and dust removed rather than shining. A soft brush, a cotton bud and warm soapy water on a cold, dismantled lamp does the job. If a burner is so corroded that the wick mechanism sticks, replacing it is easier and safer than restoring it, and stockists who list burners and galleries by size, such as https://lamplight.us.org/, make matching one straightforward.

A gentle cleaning routine

• Work only on a cold, empty lamp, dismantled as far as it comes apart easily.
• Wash with warm water and a little washing-up liquid, then dry completely.
• Use a mild paste only on bare brass, and only where you want it brighter.
• Keep polish away from the wick, the wick slot and the glass.
• Dry every thread and hole before reassembly, since trapped water corrodes.

Household remedies, honestly assessed

Lemon juice and salt, or vinegar and bicarbonate, will brighten bare brass and they are acidic enough to etch it if left on. If you use them, work in small areas, rinse thoroughly with clean water and dry at once. They have no advantage over a proprietary paste except that you already own them.

The bits that are not brass

Plenty of fittings are brass-plated steel or a brass-coloured alloy, and polishing those wears straight through the finish to a grey layer beneath. If a magnet sticks to the fitting, it is not solid brass, and you should limit yourself to a damp cloth.

Corrosion around the fount

Fuel that has been left to sit on the metal, particularly around a filler cap, leaves a dull film and eventually attacks solder joints. Wipe the fount after every fill rather than letting it accumulate. Green or crusty deposits at a seam on an old lamp are a warning about the integrity of the fount, not merely a cosmetic issue.

How often is enough

Functionally, once a season: strip the burner, clean the air holes, check the wick mechanism and dry everything. Cosmetically, as rarely as you can bear. A lamp that gets used weekly and cleaned lightly will look better in ten years than one polished to a gleam every month.