Original Sculpture
Our Fat Boy project started with the creation of a small model of the sculpture measuring just 11 inches long. This was created in clay over a wire frame.

The model was handed over to our foundry which then had the job of producing the full size sculpture.

In this case we asked the foundry artisans to scale up our model 20 times to produce a twice life size Fat Boy.

The scaling up process starts with producing technical drawings of our model to ensure that the proportions and dimensions are correct.

Skilled artisans are able to produce an exact facsimile in every detail of the original small 11 inch model.

Rubber Mould
Our foundry uses the “lost wax” process which requires making a mould of the full size sculpture. This is done by “painting” several layers of liquid silicon or rubber on the sculpture.

The rubber mould captures every sculpted detail. This mould is subsequently coated in a plaster “jacket” before being removed.

The plaster provides the mould with rigidity holding the original contours of the rubber mould firmly in place.

Due to the size of the sculpture the mould was cut into 20 sections before being removed.

The Wax Casting
Several layers of liquid wax are now poured into the rubber mould. Once the wax has cooled it is removed and an artisan corrects any errors in the wax so that it remains true to the original sculpture.

Sprung
Wax rods, called gates, are attached to the wax pattern to allow the even flow of molten metal and to prevent air and gas from being trapped when the molten bronze is poured in.

Ceramic Shell
A ceramic shell is now created around the wax. Eight layers of ceramic are applied to the wax mould both inside and out and left to cure for several days. Once fully cured the ceramic encased wax is placed in a kiln. This bakes the ceramic and at the same time the wax is lost hence the term: “the lost wax” process.

Once this process is complete a ceramic mould is all that is left with a cavity into which the molten bronze will be poured.

Casting
After being heated in a kiln the molten bronze is poured into the mould at a temperature of 2100°F. (Bronze is an alloy which is 95% copper, 0.2% lead, 0.2% tin, 0.6% zinc and 4% silicon).

Breakout
After it has cooled the ceramic shell is carefully removed revealing a rough casting. The gates (rods) are cut off and the casting is sand blasted and cleaned up ready to be welded to the other parts of the sculpture.

The various parts are now carefully aligned and welded together. The welds are then “chased” out so that they are invisible to the naked eye.

Patina
Next the finished bronze was coloured using chemicals and heat.

Clive and I wanted a very dark bronze finish to give the sculpture depth and texture. We are keen that the finished sculpture will be touched giving certain areas a worn look. This process will add new dimensions and interest to the piece as time passes by.

Internal Structure
Although hollow, the sculpture weighs approximately 3 tons. The thickness of the bronze varies between ½” to 1”. Bronze is an alloy and has tremendous intrinsic strength, however, because we want to take it on a 2,500 mile road tour starting at the foundry in Braintree and then across the Atlantic by ship to Baltimore and on by road to Milwaukee, we needed to allow for the unusual stresses and strains that it will be subjected to.

We employed a structural engineer to design a special internal support framework and base to enable the sculpture to safely undertake this unique journey.

The sculpture appears to have no support other than the base allowing the public an unimpeded view whilst it is travelling on the back of an open trailer.

In reality the sculpture has two large stainless steel discs which have been tig welded to the inside of each wheel. These discs have a steel post which goes through the bottom of the wheels and into the base securing the sculpture.

The side stand provides the third point of support. It has a steel rod through it which is welded to the base at one end and a large steel plate inside the bottom the sculpture at the other.

Skilled Craftsmen
Up to 10 skilled craftsmen worked on our sculpture at any one time. Some of them are accomplished artists in their own right and without their help and support our project would not have been possible.

Trivia
Clive and I did not know anything about Harley-Davidson when we embarked on this project in 2002. About three months into it we discovered that it was their 100th anniversary in 2003.

Once we knew this fact we decided that the sculpture had to be ready to be taken to Milwaukee to be part of the celebrations. The only problem was time.

The foundry we had chosen undertakes Royal commissions and we had to persuade them to set aside a commission for the Queen in order to complete our sculpture in time to get it to Milwaukee for 31st August.

Permission was sought and duly received allowing the foundry to delay the completion of a magnificent sculpture of the Queen on horseback.

We would like to take this opportunity to thank Her Majesty for her help and support.