Bronze Casting & Sculpture Processes

Arch Bronze is a fine art foundry in Putney, London, working with artists, galleries and studios on sculpture at a wide range of scales.

Our work covers the full production process, from mould making and model development through to bronze casting, fabrication, patination, restoration and installation. The methods used vary from project to project according to the original artwork, material, scale and intended finish.

This page provides an overview of some of the principal processes and materials we work with.

Lost-Wax Bronze Casting

Lost-wax casting is one of the principal methods used to produce bronze sculpture. It allows complex forms and fine surface detail to be faithfully reproduced from an artist's original model.

The process begins with a mould of the original sculpture, from which a wax reproduction is made. The wax is then prepared for investment and casting before the finished bronze is chased, assembled and prepared for its final surface treatment.

Arch Bronze uses lost-wax casting for work ranging from small, highly detailed pieces to larger and more complex sculpture.

Plaster Investment Casting

Plaster investment is used as part of the lost-wax bronze casting process. The wax model is surrounded by a carefully prepared refractory plaster investment which forms the mould into which the molten bronze is ultimately cast.

The quality of the investment stage is important in retaining fine detail and producing a clean, accurate casting.

Arch Bronze has extensive experience using plaster investment for fine art bronze sculpture of different sizes and levels of complexity.

Sand Casting

Sand casting is a traditional metal casting process in which a mould is formed in specially prepared sand around a pattern or model.

It is particularly useful for certain larger, simpler or more robust forms, and can be an effective method where the character of the sculpture, scale of the work or required production method makes sand casting more appropriate than lost-wax casting.

Where a project requires it, we work closely with a trusted specialist foundry, coordinating the process as part of the wider production of the sculpture. This allows sand-cast elements to be integrated with our own fabrication, chasing, finishing and patination work where required.

Ceramic Shell Casting

Ceramic shell is an alternative investment method used within the lost-wax casting process. Rather than surrounding the wax in a solid plaster investment, the wax is repeatedly coated with layers of ceramic slurry and refractory material to build up a strong shell.

The process can be well suited to complex forms, fine detail and certain scales of sculpture, and offers different technical advantages depending on the work being cast.

For projects where this method is the most appropriate, we work closely with a specialist partner foundry and coordinate the casting as part of the overall production process. The resulting bronze can then return to Arch Bronze for chasing, assembly, fabrication, patination and finishing.

Silicone Mould Making

Silicone rubber is widely used for mould making because of its ability to reproduce very fine detail while remaining flexible enough to release complex shapes.

It is particularly suited to sculpture with detailed surfaces, undercuts and delicate modelling.

The silicone mould is normally supported by a rigid outer case, allowing repeated waxes or casts to be produced while retaining the form and character of the original artwork.

Plaster Piece Moulds

Plaster piece moulding is a traditional mould-making technique in which a mould is constructed from a number of separate plaster sections.

It can be particularly appropriate for certain forms of sculpture, models and objects where a rigid mould provides the most suitable method of reproduction.

Careful planning of the individual sections allows the mould to be removed from the original and reassembled accurately for casting.

Gelflex Moulds

Gelflex is a flexible mould-making material that can be used for a variety of sculptural applications.

Its flexibility allows it to reproduce surface detail while being removed from forms that would be difficult to mould using a completely rigid material.

The most suitable mould-making material is selected according to the sculpture, its surface, complexity, scale and the number of casts required.

Alginate and Life Casting

Alginate is a fast-setting mould-making material commonly used where direct moulding of the body or other delicate subjects is required.

Because it sets quickly and can reproduce fine surface detail, it is particularly useful for life casting and other short-duration mould-making applications.

The resulting mould can then be used to create a positive model from which further moulding or casting processes can be undertaken.

Cold Casting

Cold casting allows sculptural work to be reproduced without pouring molten metal.

Materials such as resin, plaster and cement can be cast directly into moulds, and metallic powders or other aggregates can be incorporated where a particular appearance or surface quality is required.

Cold-cast methods can be useful for studies, editions, models, architectural elements and projects where traditional metal casting is not necessary.

Resin Casting

Resin is a versatile material that can be used for finished sculpture, models, reproductions and elements that will form part of a wider production process.

It can reproduce fine detail and can be combined with fillers, pigments and metallic powders to achieve a range of different finishes.

Resin casting may also be used where weight, cost, production method or intended environment makes it preferable to a cast metal object.

Aluminium, Brass and Pewter Casting

Although bronze is central to the work of the foundry, other non-ferrous metals can also be appropriate for sculpture.

Arch Bronze can cast in metals including aluminium, brass and pewter where the material suits the design and intended finish of the work.

Each metal has different characteristics in terms of weight, colour, surface treatment and casting behaviour, so the material is considered as part of the wider production process.

Sculpture Enlargement

Artists frequently begin with a small maquette or model before developing a work at a much larger scale.

Sculpture enlargement involves translating the proportions, form and character of the original model into a larger version while retaining the qualities of the artist's work.

Depending on the project, enlargement may involve traditional model-making methods, digital processes or a combination of both.

Model Making

Model making can form an important part of developing a sculpture before moulding, casting or fabrication begins.

Arch Bronze can work from drawings, photographs, maquettes and existing sculpture to develop models and production components for subsequent stages of manufacture.

The approach is adapted to the individual project, with close attention paid to scale, proportion, surface and the artist's original intention.

3D Scanning

3D scanning can be used to capture the form of an existing sculpture or model digitally.

The resulting digital file can be useful for enlargement, reproduction, modification, archiving and preparation for 3D printing or other manufacturing processes.

Where appropriate, Arch Bronze can incorporate or coordinate 3D scanning within a wider sculpture production project while maintaining the artist's involvement throughout the process.

3D Printing

3D printing can be used to create physical models, components or enlarged forms from digital files.

Within sculpture production, it can be particularly useful for translating a scanned or digitally developed model into a physical object that can subsequently be refined, moulded, cast or incorporated into a larger construction.

Arch Bronze uses digital production where it offers a practical advantage while retaining traditional sculptural judgement and hand finishing where required.

Sculpture Fabrication and Welding

Not every sculpture is produced entirely through casting. Larger or structurally complex works may require fabricated components, internal frameworks, armatures or supporting structures.

Fabrication can involve cutting, forming, fitting and welding metal components before they are assembled into the finished sculpture.

Where fabrication and casting are combined, the structure, weight, balance and final installation requirements can be considered together from an early stage in the project.

Bronze Chasing and Fettling

Once a bronze has been cast, the individual sections require cleaning and finishing before the sculpture is ready for patination.

Chasing involves refining the surface of the bronze, correcting casting seams, blending welded joints and restoring details that may have been affected during the casting and assembly process.

Fettling removes unwanted casting material and prepares the metal for subsequent finishing. The aim is for the completed bronze to read as a single resolved sculpture rather than a series of separately cast elements.

Bronze Patina

Patina and patination are the process of developing colour and surface character on bronze using controlled chemical reactions.

Different chemicals, temperatures and methods of application can produce a wide range of colours and tonal effects, from subtle browns and blacks to greens, blues and more complex layered finishes.

At Arch Bronze, patination is treated as part of the artistic process. Finishes are developed in discussion with the artist and can be adapted, refined or matched across an edition where required.

Polishing and Finishing

The final finish of a sculpture has a significant effect on the way its form, colour and surface are perceived.

Depending on the work, finishing can include polishing, brushing, texturing, waxing and other hand-applied treatments.

Some sculptures require a highly refined polished finish, while others retain evidence of modelling, casting or fabrication. The finishing process is therefore tailored to the character of each individual work.

Bronze Sculpture Restoration

Bronze sculpture can require restoration as a result of age, environmental exposure, accidental damage or previous repairs.

Restoration work may include cleaning, repairing damaged surfaces, structural repairs, replacing missing components, recasting elements and restoring or adjusting the patina.

Each sculpture is assessed individually, with the aim of preserving the character of the existing work and carrying out only the intervention necessary.

RepATINATION

Existing bronze sculpture sometimes requires the original surface colour to be restored, altered or matched following repair.

Re-patination involves carefully preparing the surface and developing a new patina that relates to the surrounding bronze.

This can be particularly important where only part of a sculpture has been repaired, as the new work needs to sit naturally alongside the existing surface rather than appearing as a visibly separate intervention.

Sculpture Installation

The production of a sculpture does not necessarily end when it leaves the foundry.

Installation can require careful planning around weight, balance, structural support, transport, access and the nature of the final site.

Arch Bronze can assist with the practical requirements involved in preparing sculpture for installation and coordinating the different stages necessary to position and secure a finished work.

Plinths, Bases and Structural Supports

Plinths, bases, armatures and internal supports often form an important part of the engineering of a sculpture.

They may need to carry considerable weight while remaining visually unobtrusive and compatible with the artist's intended presentation of the work.

Support structures can therefore be developed alongside casting and fabrication so that the finished sculpture, its base and its installation method operate as a coherent whole.

Working with Arch Bronze

Every sculpture presents different technical and artistic considerations, and there is rarely a single production method suitable for every project.

Arch Bronze works with artists, galleries and studios from the early stages of a project through mould making, casting, fabrication, finishing, restoration and installation.

For advice on a particular sculpture or project, please contact the foundry to discuss the work.