Bronze, brass and copper: what you are actually buying

Three words get used loosely in this trade, and the looseness costs money at the point where a customer compares two pieces on a shelf.

The short version

• Copper is the pure metal: soft, reddish, and rarely used on its own for cast décor because it is difficult to pour into fine detail and dents easily.
• Bronze is copper alloyed mainly with tin. It pours well, holds fine relief, and ages to the familiar dark brown-green. It is what most temple and memorial work is made from.
• Brass is copper alloyed mainly with zinc. It is yellower, brighter when polished, and common in decorative hardware and lighter altar pieces.

In Vietnamese the distinction is made differently again — dong do, dong vang and dong cat tut describe colour and stock origin as much as chemistry — which is one reason specifications get lost in translation between a buyer's office and a workshop.

What actually matters on your order

Rather than argue about a word, put four things on the purchase order:

1. Colour reference. A signed-off physical sample beats any name. Colour is the thing your customer sees first.
2. Wall thickness. This is where cheap work hides. Ours is 5 mm, 8 mm at load points. A piece at 2 mm will look identical in a photograph and feel wrong in the hand.
3. Cast weight. Weight is the honest proxy for metal content. If two quotations for the same piece differ by 30 %, compare the weights before you compare the prices.
4. Finish and its maintenance. Antique patina, reinforced patina, polished, lacquered. Each ages differently, and a polished piece in a coastal house needs waxing.

Patina, and why two pieces in one set should be cast together

Patina is a chemical finish applied by hand and then stabilised. Two castings finished in different weeks, or in different workshops, can be a shade apart — visible when they stand side by side on an altar, invisible in separate photographs. If a set is going to be sold as a set, have it cast and finished as a set, and say so on the order.

Questions worth asking a supplier

• What is the wall thickness, and at the load points?
• What does this piece weigh, cast and packed?
• Is the piece cast solid, or spun or pressed from sheet?
• Will the colour be matched across the whole order, or item by item?
• If my market requires a lead-content declaration, what can you support in writing?

Any workshop that casts its own metal can answer all five in a sentence each. A trading company will need to go and ask.