How do you keep copper shiny?

The question that comes after the first polish

You polished your copper, it shone like new, and a week later that shine has already softened. This is the moment when a lot of people wonder whether they are doing something wrong. You are not. You are looking at the only common material in the house that visibly responds to the air around it, and that is exactly the material you chose.

Below is how to bring the shine back and, more to the point, how to keep it.

In short

• Pure copper is salmon pink by nature. The warm reddish brown you know is a very thin layer of oxide on top of it.
• That layer comes off with acid: half a lemon with coarse salt, or citric acid dissolved in lukewarm water.
• Baking soda is not acidic but mildly abrasive. It smooths the surface, so it shines more, while the oxide stays put.
• Always treat the whole object at once. Doing one part and not another is exactly what creates blotches.
• Rinse under running water rather than wiping, especially on hammered and twisted copper.
• A very thin layer of microcrystalline wax after polishing stretches the shine from days to weeks.
• Without air almost nothing happens: store what you are not using in a closed pouch.

Why copper changes colour

Copper is one of the few metals with a colour of its own. Freshly polished that colour is salmon pink, and within a few days a very thin layer of copper oxide grows on top. That layer is the warm reddish brown most people call "copper coloured". Leave it alone for years and it deepens, eventually turning green. What happens then, and what it means, is in why copper turns green or black.

That change is the visible proof that you have solid copper in front of you. A product with a lacquer coat over it never changes colour, because air and water never reach the metal. Ours is independently measured at 99.21% pure copper, with no coating and no inner lining, and you can watch that happen in the colour. What was measured, and by whom, is in what our copper products are made of.

What sets the pace

How fast that layer grows depends mostly on oxygen and moisture. A bottle you rinse and dry straight away stays bright far longer than one left standing wet. Heat speeds it up, so a mug sitting in the sun all day will colour sooner.

And skin plays its part. Sweat carries salt and acids, and hand cream, perfume and chlorinated water add to that. This is why a bracelet colours faster than a jug in the cupboard, and why it colours faster on one person than on another. That says nothing about your care; it says something about the circumstances.

Step 1: even first, shiny second

Never polish only the spot that bothers you. Always treat the whole object, because doing one part and not another is exactly where the blotchy look people worry about comes from.

On a smooth surface half a lemon with coarse salt (not too hard: salt is mildly abrasive and dissolves well in the lemon juice) does the job: fine scratches show up more easily on a smooth, mirror-like surface than on a hammered one. On hammered and twisted copper, citric acid works better: dissolve a teaspoon in a cup of lukewarm water and apply it with a soft cloth or an old toothbrush. A solution reaches everywhere equally, and on a relief that is the difference between even and blotchy.

Leave it for a couple of minutes at most and never let it dry on.

Then rinse it under running water rather than wiping it off. This is the step that gets skipped most often. Acid left behind simply carries on working, and a cloth does not reach into the grooves of a hammered or twisted surface. A trace stays there and keeps working on that one spot, which produces exactly the blotchy pattern you set out to remove. Twenty seconds under the tap, turning the piece as you go, then dry it completely with a soft cloth straight away.

Which household remedy does what, and what to avoid, is in cleaning copper: soda, vinegar, lemon or citric acid.

Step 2: the layer that makes the difference

This is where almost every set of instructions stops, and it is where most of the gain sits. If you want the shine to last, you keep the air off the metal.

You do that with microcrystalline wax, the stuff museum conservators use on metal objects. After polishing, apply a very small amount with your finger or a soft cloth, including in the grooves, then buff it out until you can no longer see or feel it. What is left is a layer thinner than a fingerprint that shields the copper without changing its colour.

On a bottle or a pyramid in a cabinet that layer lasts months. On a bracelet it slowly wears away where it rubs against your skin, so there you repeat it every few weeks. If your skin is sensitive, try it on a small area first.

One thing to skip is clear lacquer or clear nail polish, a tip that circulates online. A coat like that wears through at the edges within weeks, and then you get shiny and dull patches side by side. It is also very hard to remove without damaging the surface.

Step 3: wearing and storing

The rest is habit, and it makes more difference than you would expect.

• Take a bracelet off before showering, swimming, exercising and washing up.
• Let hand cream, sunscreen and perfume soak in before you put it back on.
• Rinse drinkware with warm water after use and dry it straight away. Leave a bottle open to dry so the inside does not stay damp.
• Store what you are not using for a while in the velvet pouch it came with, and press the air out. Without oxygen almost nothing happens.

The full routine for drinkware, storage included, is in caring for a copper bottle.

How often is it needed?

Needed, never. Polishing is there for the shine and not for safety: copper with patina is no less clean than copper that gleams. So it comes down to what you find beautiful.

Someone who wants to keep the shine crisp and works with wax spends about five minutes on it every three to four weeks. Someone who only polishes, without wax, does it more often, roughly weekly or fortnightly. And someone who lets the colour deepen does nothing at all, and is just as right. On hammered copper, incidentally, early patina shows less than on smooth, because the facets break up the light; that difference is in smooth or hammered copper.

Why this always works with copper

On a gold-plated or lacquered piece of jewellery, the colour that comes off is gone for good. That layer is thin, it wears, and another metal appears underneath. Polishing it back is not an option.

With solid copper you polish into the material itself, because there is no layer: inside and outside are the same. That is why you can bring a ten-year-old bracelet back to the colour it arrived in, and do it again ten years from now. With copper the shine is yours to set, over and over. What the metal does over the long run is in copper objects that outlived the centuries.

Have a look at the copper bracelet, the water bottle, the mug and the jug, or browse the full range.