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



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



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



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



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



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



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



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



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