Bronze Casting: How Nick’s Sculptures Are Cast
All Nick’s sculptures are cast in small limited editions of between 3 and 25, by Pangolin Editions Foundry, Chalford, Gloucestershire, chosen for their outstanding artistry, craftsmanship and commitment to quality. Pangolin cast each sculpture by hand, using the lost wax, or cire perdue casting method (with the exception of very large pieces which are cast using a hybrid, wax, sand, casting method). First used over 5500 years ago, lost wax casting today remains essentially unchanged from lost wax casting in antiquity. It continues to be an enormously skilled and labour intensive process.Read more...
Pangolin Editions are probably the best Fine Art Foundry in Europe. In addition to casting Nick’s sculptures, they also cast the works of Rembrandt Bugatti, Lynn Chadwick, Geoffrey Dashwood, Antony Gormley and Damien Hirst, to name but a few. Nick has used Pangolin exclusively for nearly 25 years. He needs a foundry as exceptional as Pangolin to reproduce the extraordinary detail and subtlety of his original sculptures.
Hand casting, finishing and patinating each sculpture is an incredibly involved and technically challenging process, requiring years of experience and many, many, hours of hard work by a team of highly trained and talented foundry men and women.
The casting process begins when Nick’s original clay, or wax sculpture arrives at the foundry. A multi-piece mould of the original sculpture is made, using several layers of silicone rubber, with outer ‘jackets’ of plaster or fibreglass to support the soft, flexible rubber. Once the mould has cured, the mould is opened and the original sculpture removed.
Next, the silicone rubber mould is used to cast a hollow wax copy of the original sculpture, made by painting repeated layers of special wax into each section of the mould, before reassembling the mould pieces and slushing molten wax inside the mould, to fill any gaps between sections. Once the wax has cooled, the hollow wax cast is removed from it’s mould, checked for any damage, or loss of detail, which has to be modelled back into the surface. A window is cut into the hollow wax sculpture, which is then filled with special plaster. A network of wax rods are joined to the surface of the wax sculpture. These will eventually become channels to feed in molten bronze and let exhaust gases escape during casting. Then the whole wax assembly is remoulded (invested) in more of the special plaster mix, which is able to take the high temperatures of the casting process. Once the plaster has dried, this ‘investment’ mould is gently heated in massive kilns until all the wax melts out of the mould, leaving a hollow void in the shape of the eventual bronze casting – hence, “Lost Wax”.
The next stage is to heat the bronze, until it is molten – over 1100 degrees C. Once the bronze is hot enough, it is skimmed to remove any impurities, then poured slowly and carefully into the investment mould. When the mould is filled it is left to cool, before the bronze casting hidden inside is carefully broken out of the plaster which encases it, and the plaster core blasted out, using a high pressure water jet. To the untrained eye, the resulting bronze looks like a piece of scrap metal, discoloured and surrounded by a web of bronze runners and risers attached to it’s surface – the casting feeds mentioned earlier.
Next comes the metalworking stage. The bronzes are often cast in several sections, due to the complexity of Nick’s original sculptures, and these sections must be welded together, using the same bronze alloy used for casting. All the runners and risers must be cut away, and any pits or other casting flaws have fresh bronze welded in to them. After this, the areas of fresh weld and any areas of lost surface detail need to be carefully carved and chased back into the surface of the bronze casting, until it exactly matches Nick’s original. Finally, the whole surface is given a thorough cleaning with wire brushes and methylated spirits to prepare the surface for the final stage – patination.
Patination is the process of treating the surface of the bronze casting with special mixes of chemicals that react with the surface of the bronze to build up layers of translucent colour. Different chemicals react in differently with the bronze, to produce different colours. But it is not that simple! The dilution of the patinating chemicals, the composition of the bronze that they are applied to, the order in which the different chemical mixes are applied and the mixes used (they react with each other as well as the bronze casting) even the temperature and humidity on the day that the casting is patinated can effect the final result. Once the layers of colour have been built up, the surface of the bronze is sealed and protected with multiple layers of protective wax. This halts any on-going chemical reactions and seals the surface of the sculpture, protecting and preserving the surface of the sculpture. Patination is pure alchemy – transforming bare bronze into something magical!
Bronze is a wonderful material; strong, beautiful and durable. There are 5000 year old bronze sculptures that look as good today as the day they were cast! Nick Bibby’s sculptures carry on that legacy.
Prices from £1,450.
If you would like to order a sculpture, enquire about availability, or commission something new, Nick would love to hear from you! Please use the Contact form, or look at our Ordering page for more information.