Escar UK Bronze : The Art of Bronze

-:-

The Art of Creating a Hollow Cast Bronze Sculpture

-:-

Let Escar UK Bronze guide you through the Art of Bronze, a hands on process used to create Hollow Cast Bronze Statues & Sculptures using the 6,500 year old Lost Wax Casting Process

-:-

THE ART OF BRONZE : RESEARCH

 
A realistic sculpture begins with Research and as many reference photos are collected of the subject as possible

 

These will include adornments, which for a person would be items such as costume and jewellery, plus any other relevant information such as any pose required

 

Special consideration is also given to photos that capture the facial expression that the artist / commissioner wishes to immortalise in the final Bronze

-:-

THE ART OF BRONZE : MODEL MAKING

 
An artist creates an original model from wax, clay or other oil based materials that allow the medium to stay soft

 

We at Escar UK Bronze prefer to use modelling wax as there is no need to fabricate an armature (a framework that supports a sculpture when it can’t stand on its own), as is required with clay

 

Modelling wax is temperature sensitive and this is its main advantage over clay as various modelling waxes behave differently, at various temperatures

 

By using different pre-made modelling waxes, the artist has the luxury to customise the hardness of the material according to the project’s needs & creative styles, simply by mixing different types of waxes and/or using additives

 

When modelling wax is cold it is hard and rigid and can be carved, when it is warm it is soft and pliable and can be moulded

 

It can be heated in a pot and painted on, or when slightly cooled it can be applied with a spatula or a knife

 

Also, leaving it to rest will allow the wax to cool down and harden, meaning that a modelling session can be interrupted and then restarted days later if necessary, without having it dry out like it would if it were clay

 

This last aspect is particularly important when awaiting feedback on a commissioned sculpture

 

When completely cool, it captures a high level of detail that is difficult to obtain with clay

 

Another huge advantage of modelling wax against clay is that it can be reused almost indefinitely and if well looked after (kept clean and stored safely), modelling wax is an ideal substrate to rework a concept, many many times over

 

And last but not least, modelling wax can be added or removed with ease

-:-

THE ART OF BRONZE : MOULD MAKING

 
A mould of two shell like halves is made from the original wax model, with each having two layers, an inner and an outer

 

The inner is normally created using latex or silicone to perfectly capture the fine detail the artist has imparted into the wax, whereas the outer is commonly made from plaster or glass fibre to support and protect the soft mould within

 

This is done by coating the wax model with liquid latex or silicone, building it up layer by layer until a thick negative of the wax positive is created, thereby capturing all the intricate details of the artist’s work

 

Once the latex / silicone has cured, it will then be reinforced on the outside using plaster, or in our case, glass fibre

 

During this process, flanges with built-in register pegs are added on the outside of the mould around the middle, to facilitate splitting it into two halves when cured, and more importantly to ensure the two halves match up perfectly when re-assembled

 

Holes are also drilled around the flange to allow the two halves to be bolted together, to prevent any movement after they have been carefully aligned

 

When cured, the mould is then carefully cut down the middle of the flanges to produce two halves and both halves are removed from the artist’s wax

 

The two halves are carefully re-assembled and molten wax is poured inside and swirled around to allow an even layer to coat the inner surface

 

This is done as many times as is necessary until the required thickness is achieved, normally around 3mm

 

Every artist is different however and will have found their own preferred quantities of wax to make their ideal cast

 

It is then allowed to cool, resulting in a hollow wax copy of the piece inside

 

The hollow space is then filled with a “slurry” of silica to give internal support to the layer of wax created in the previous process

 

Once set, the mould is then removed from wax copy and the mould is put into storage for making duplicates

 

Each copy is then “Chased”

 

This is where a heated metal tool will be used to hide any imperfections in the wax and remove the line produced by using a mould of two halves

 

Any additional pieces that were moulded separately but need to be cast as a whole, would also be added at this point

 

The wax copy is then ‘Sprued’ with a treelike structure of wax, that will eventually provide paths for the molten casting material to flow in and for air to escape

 

The sprued wax copy is then alternately dipped into a “slurry” of silica and a sand-like stucco, the combination of these two materials being known as the Ceramic Shell Mould

 

This process is repeated until ½ an inch of Ceramic Shell Mould coats the wax copy

 

The next stage is to turn the mould upside down to retain the wax, fire it in a kiln to harden the ceramic shell, to make it strong enough to endure the heat of molten bronze, during casting

 

Once hard, metal pins are hammered through the outer shell, through the wax and into the inner core, to keep the inner and outer moulds in register once the wax is melted and poured away

 

It is then brought up to temperature and hardened, then turned upright to allow the molten wax inside to drain off through the sprued vents & tunnels, leaving a hollow space between the inner and outer ceramic moulds

 

It is at this point our process gets it’s name, the “Lost Wax Casting Process”

 

Before the molten bronze is added, the mould will first be tested using water to find any weak points or holes where leaks may occur

 

Any damage can be repaired, holes patched and if required, additional holes drilled to aid draining

 

Now it is secure and strong, the shell is heated once again in the kiln to remove any remaining moisture and to ensure it is at a similar temperature to the molten bronze to prevent shattering due to temperature difference

 

Our final mould is now ready for casting our Bronze Piece

-:-

THE ART OF BRONZE : CASTING

-:-
First bronze metal is melted in a furnace at roughly 1200 °C until molten

 

It is then transferred to a crucible for safety and ease of transport and poured into the pre-heated mould

 

Once the mould is filled with a sufficient amount of molten bronze, it is then left to cool

-:-

THE ART OF BRONZE : BREAKING THE MOULD

 
Once cool, the bronze casting is now released by drilling away the inner core, hammering away the outer shell and removing the sprues,
 
These will be melted back down and used again but the ceramic shell is lost
 
The metal chasing process is now employed, the same as with the wax chasing, to remove all casting marks and signs of casting
 
Imperfections or pits from air bubbles can be removed by filling the surface and where the sculpture has been cast in several pieces, these are welded together and re-finished

-:-

THE ART OF BRONZE : PATINATION

 
Finally you have a finished bronze cast of your original sculpted model, which is then prepared for patination

 

This is the art of colouring of the sculpture using various chemicals, different combinations of which create various colours

 

The sculpture is then protected with layers of wax applied under heat, followed by two cold applications and then buffed to reach a fine lustre

-:-

THE ART OF BRONZE : MOULD DEGRADATION

 
Overtime and after repeated use, the definition will be reduced and a new mould will need to be fashioned

 

This is something we keep a close eye on to ensure that our current moulds produce a finely detailed firing wax, to the quality of the original

 

If degradation occurs, the current wax is returned to the artist, the lost details reinstated, new moulds are created and the old moulds are scrapped

        

THE ART OF BRONZE : CONCLUSION

 
As can be seen from the narrative above, the Art of Bronze is a very hands-on process that goes through many stages before the final patinated and polished bronze sculpture is ready for delivery to the customer

 

We do hope the information contained within has been informative and we look forward to making your acquaintance, sometime in the future
 
 
The Escar UK Bronze Team

-:-

Escar UK Bronze -:- The Art of Bronze

 

Wikipedia -:- For more info on Lost Wax Casting -:- The Crucible

 

Hollow Cast Bronze Statues UK -:- Hollow Cast Bronze Sculptures UK