What is the difference between lost-wax casting and sand casting?

Sand casting uses a packed sand mould pressed with a master pattern. It is faster and less expensive, but the mould surface is grainy and dimensional accuracy is lower. Lost-wax casting uses a ceramic shell investment taken from a wax replica, capturing far finer surface detail. For decorative sculpture and figurative work where texture, expression, and edge sharpness matter, lost-wax is the correct process. Sand casting is appropriate for mechanical and architectural components where precision of detail is secondary.

What is the difference between lost-wax bronze and cold-cast bronze?

Lost-wax casting produces an object made entirely of metal alloy. Cold-cast bronze is a different process: polyester resin mixed with bronze powder, moulded at room temperature. Cold-cast pieces are not metal castings. They are resin composites with a metallic appearance. They are lighter, less durable, and do not develop a true patina over time. Classic Art Collection produces only true lost-wax cast bronze and brass.

How long does a bronze sculpture take to make?

At Classic Art Collection, a custom bronze cast from the client's own design takes 2 to 3 months, and most clients commission custom work. The shorter lead time of 3 to 5 weeks applies only to Classic Art Collection's own designs or to stock on hand, which traders can order directly. A single piece or prototype waits for space in the furnace, so allow up to about 3 months. Ordering a lot avoids that queue because the pieces are cast together: for an edition of 99, for example, order 20 at once rather than one at a time. Wholesale orders of Classic Art Collection's own designs start at a minimum of 20 pieces per order. Custom work from the client's own design has its own minimum, set per design: roughly twenty pieces for small items and ten for larger ones.

Why is cast bronze expensive?

Every step in the lost-wax process is labour-intensive and cannot be significantly accelerated. The ceramic shell is built by hand, one coat at a time. Chasing, the most skilled stage, is performed entirely by hand and takes longer than casting. The metal itself is not cheap, and the choice of alloy affects price: silicon bronze (used for museum editions, collector pieces, and artist projects) commands a premium over brass (used for functional objects, hobbyist editions, and real estate installations). The process also generates unavoidable waste: sprues, failed shells, and pieces that do not pass inspection.

Can lost-wax casting reproduce fine detail accurately?

Yes. This is one of the defining characteristics of the process. The wax pattern picks up every detail from the rubber mould, including the original sculptor's tool marks, fingerprints in the clay, and surface transitions measured in fractions of a millimetre. The ceramic shell captures these from the wax. The poured bronze inherits them. The limiting factor on fine detail is not the casting process. It is the chasing and patination stages. At Classic Art, preserving the sculptor's surface is the first standard against which chasing is judged.

What Is Real Bronze? Why You Should Ask Your Foundry for the Alloy Percentage

classicartcollection

7 days ago

6 min read

Real bronze is a cast metal alloy made mostly of copper, with tin or silicon as the main partner metal. Brass is copper with zinc. "Cold cast bronze" is not cast metal at all: it is resin mixed with bronze powder. All three can look similar on the day you unwrap them. They do not behave the same over the next twenty years.

That is why the single most useful question you can ask a foundry is simple: which alloy is this, and what is it made of? Then ask for the answer in writing, on the quotation and on the invoice.

What does "bronze" actually mean?

Bronze is a family of alloys, not one fixed recipe. What they share is copper as the main metal. The partner metal changes the character of the alloy.

Tin bronze is the classic version: copper and tin. For example, one standard cast tin bronze, UNS C90500, is listed by the Copper Development Association at 86 to 89 percent copper, 9 to 11 percent tin and 1 to 3 percent zinc.

Silicon bronze swaps tin for silicon. One standard cast silicon bronze, UNS C87300, is listed by the same association at a minimum of 94 percent copper, with 3.5 to 4.5 percent silicon and a little manganese.

These are typical industry figures for standard alloys, published so engineers and buyers can compare like with like. They are a reference point, not any particular foundry's recipe. Every foundry chooses its own alloy, which is exactly why you should ask which one you are getting.

Is brass the same as bronze?

No. Brass is copper alloyed with zinc, and it is a different metal. Zinc, not tin or silicon, is its main partner metal, and that gives brass its own colour and behaviour.

Brass is not a lesser material. It casts beautifully, takes a patina, and reaches a finish very close to bronze at a more approachable cost. For functional objects and large architectural quantities it is often the right choice. It is simply not bronze, and it should never be sold as bronze.

What is "cold cast bronze"?

Cold cast bronze is resin (a type of plastic) mixed with bronze powder and poured into a mould at room temperature. The powder gives the surface a metallic look, and it can be polished or tinted to resemble a patina.

It is not molten metal and it is not a bronze casting. You can usually tell by weight: a cold cast piece feels much lighter than a metal one of the same size. It is also far less durable, especially outdoors. If a listing says "bronze" and the price looks too good, ask directly whether the piece is cast metal or resin.

Why does the metal mix matter so much?

Because the alloy decides almost everything about how the piece looks, lasts and holds its value.

Colour. More copper gives a warmer, deeper tone. Zinc pushes the colour toward yellow. The raw metal is the base every finish is built on.
How the patina takes. A real patina is a reaction with the metal itself, not paint on top. Different alloys react differently, so the same finish applied to two different metals can come out two different colours.
Strength. The alloy affects how tough the piece is and how well thin or delicate parts hold up.
Outdoor life. Copper-rich bronzes are known for standing up well to weather. How any metal ages outside depends on its composition and its setting, so tell your foundry where the piece will live.
Weight and feel. Solid cast metal has a weight in the hand that resin cannot fake. Collectors notice.
Value and resale. A buyer, appraiser or insurer will want to know what the piece is made of. "Bronze, alloy stated on the invoice" is worth more than "bronze, probably."

Why can an unknown alloy look fine on day one?

Fresh out of the foundry, with a patina and a coat of wax, almost any copper-based metal can look like bronze. The differences show up later.

A low-copper mix, or metal melted down from unsorted scrap, has a composition nobody can state with confidence. Because a patina is a chemical reaction with the metal, an unknown mix can take colour unevenly, shift tone over the years, or age differently from piece to piece in the same edition. You will not see this in a photograph. You may see it in five years.

This is the honest reason to ask for the alloy: not because cheaper metal is always bad, but because you deserve to know what you are paying for, and to choose it on purpose.

What should I ask any foundry before I commission?

Keep it short and put it in writing:

What is the exact alloy? A name like "silicon bronze" or "brass" is the minimum. A standard designation or a stated composition is better.
What is it made of? Ask for the main metals and their approximate proportions.
Will the alloy be named on the quotation and the invoice? If a foundry will not write it down, that tells you something.
Is it the same alloy for every piece in the edition? Consistency matters for a series.
Is this piece cast metal? If there is any doubt, ask whether it is resin or cold cast.
Is this alloy right for where the piece will live? Indoors, sheltered, or fully outdoors.

A good foundry will answer all of these without hesitation.

Which metals does Classic Art Collection cast?

We cast in two metals. Classic Art Collection names the alloy in every quotation.

Silicon bronze is our metal for collectors, artists and museum work. Brass is our metal for functional objects, hobbyist pieces and real estate projects. Each one is called by its real name, so you always know which you are buying and why.

If you are not sure which suits your piece, tell us what it is, who it is for and where it will stand, and we will recommend one. For how a project runs from first email to finished piece, see How to Commission a Bronze or Brass Casting. For how the metal is poured, see Ceramic Shell, Burnout and the Bronze Pour, and for how the surface colour is built, see Chasing and Patination. If you are an artist or designer preparing your first casting, start with Bronze Casting for Sculptors and Designers.

Frequently asked questions

What is real bronze?

Real bronze is a cast metal alloy that is mostly copper, with tin or silicon as the main partner metal. It is poured molten into a mould and becomes solid metal.

What is the difference between bronze and brass?

Bronze is copper with tin or silicon. Brass is copper with zinc. They look similar once finished, but they are different metals with different colour, behaviour and cost.

Is cold cast bronze real bronze?

No. Cold cast bronze is resin mixed with bronze powder and moulded at room temperature. It is not cast metal and it is lighter and less durable than a true bronze casting.

Why should I ask for the alloy percentage?

Because the alloy decides colour, how the patina takes, strength, outdoor life and resale value. Asking for the composition in writing means you know exactly what you are paying for.

What is silicon bronze?

Silicon bronze is a copper alloy with a small amount of silicon. One standard cast silicon bronze, UNS C87300, is listed by the Copper Development Association at a minimum of 94 percent copper. It is a typical industry reference, not any particular foundry's recipe.

Can an unknown alloy look the same as bronze?

On day one, often yes. The differences tend to appear over time, in how the patina holds and how the piece ages, especially if the metal's composition is unknown.

Which metal does Classic Art Collection use?

Silicon bronze for collectors, artists and museum work, and brass for functional objects, hobbyist pieces and real estate projects. The metal is named on every quotation.

Classic Art Collection is a family-owned bronze and brass foundry in Bangkok, Thailand, casting for artists, collectors and museums since 1991. Send photographs, drawings or a 3D file with the finished size and quantity, and we will quote it with the metal named in writing.