Brass, bronze or copper: what is the difference?

All three are copper, more or less. Copper is the pure metal. Brass is copper with zinc added. Bronze is copper with tin (and sometimes silicon, aluminium or other elements). The alloying changes the colour, the hardness and how each one ages.

At a glance

	Copper	Brass	Bronze
Made of	Pure copper	Copper + zinc (e.g. 63 % / 37 %)	Copper + tin (around 88 % / 12 %)
Colour when new	Pinkish red	Bright yellow	Brown-gold
Colour when aged indoors	Dark brown	Warm, deep brown	Chocolate brown
Hardness	Soft	Medium	Hard
Best for	Hammered vessels, cookware, anything shaped cold	Lamps, pierced work, trays, door furniture	Castings, outdoor fittings, hinges, knockers
Magnetic?	No	No	No

Brass

Copper and zinc. The brass we use for sheet work is 63 % copper and 37 % zinc — its standard name is CuZn37. It is the easiest of the three to cut, pierce and polish, and it has the brightest colour, which is why it is the classic metal for Moroccan lamps and for raised bowls and trays.

It work-hardens as you hammer it and has to be softened by heating (annealing) as you go — we describe that in anatomy of a forged bowl.

Bronze

Copper and tin, classically; modern "silicon bronze" replaces much of the tin with silicon. Bronze is harder and resists corrosion better than brass, particularly outdoors and in salt air. It casts beautifully. We use it for anything that is cast, turns, or lives outside — a door knocker, for instance, is best bronze on bronze throughout.

Copper

The pure metal. Softest of the three, and the best conductor of heat, which is why it is used for cookware (tinned on the inside for food). It hammers very well and takes a deep pinkish-brown patina. Left outdoors and wet for years, copper and its alloys can form green verdigris; indoors they almost never do.

Copper trays and pans meant for food are tinned on the inside.

Nickel silver

The fourth metal you will meet in Moroccan work. Copper, nickel and zinc; silver-white in colour; no silver in it at all. It is called maillechort in Morocco and used for silver-coloured lamps and tea trays. It tarnishes more slowly than brass and to a greyer tone.

Solid or plated?

All of the above are non-magnetic. If a magnet sticks to a "brass" object, it is steel with a brass-coloured plating — see why we stopped plating anything, and the five checks for a real brass lamp.

Caring for them

The same rules work for all three: a dry cloth, a mild polish when you want it bright, never anything abrasive. The details are in how to care for solid brass.