Bronze and Fir
With scans and 3D printing, I made my way to a first figure in bronze. In the process, multiples were created that could even have been eaten if they hadn’t been coloured.
There are figures that I know: everything is right. I wanted to develop «Farsight» and «Selfieman» from the Balance series (here’s the story about them) further. The man with a mobile phone became my first bronze, and both are printed as 3D multiples in limited editions. Along the way I learned a few things.
Scan instead of print
At the beginning of 2022, I began to clarify options for bronze casting. What would the process cost, and what is the best way to proceed? After numerous discussions with foundries, 3D professionals and artists, I decided on a 3D scan. Classically, the path from the original leads via an impression to the castable mould. In doing so, my figures would have had to be sealed first, which leaves traces or leads to minor damage.
Saw image obtained
I first tried the scan-to-print route five years ago with «Little Doris 1 & 2». The original had already been sold, so I wanted to preserve it at all costs. But unfortunately, the scans were not detailed enough; edges and transitions were rounded, and the multiples had little of the chainsaw original. Meanwhile, the scans have not only become cheaper but also much more accurate.
Sculpture as a file
The scanner looks like a large hand torch; with it, the object is photographed from all sides. At the same time, a three-dimensional shape appears on the monitor. Where there are still gaps, the scanner passes over it again. Until «Selfieman» and «Farsight» can be turned and rotated in space without gaps using the 3D mouse. This takes about ten minutes, thanks to the powerful computer.
Scaling the shape
With this data, I ask for various quotations: The goal was a print in plastic that could be moulded precisely (i.e. thick enough) and would burn out without leaving a trace. This way, the 3D print replaces the wax mould of the classic process. I have the Selfieman printed as a test in its original size. He seems too big for a bronze figure—I decide to scale him down to 70 per cent. That is the great advantage of this process: with the data, various options open up in realisation.
Test casting in miniature
After various casting offers, I make the first tests with Andreas and Richard Bründler in Winterthur: how does the moulding and burning out work with the chosen plastic pressure? We cast a miniature figure in bronze as a test run. It looks good. Now I have the definitive mould printed, bring it to Winterthur, and the «Selfieman» waits in the production queue for his fulfilment in bronze.
The power of fire
As a first step, channels are attached to the 3D-Form for the liquid metal to be poured in and the air to flow out simultaneously. Then the Bründler brothers encase the plastic print in fireclay. It is also filled with a fireclay core, and heat-resistant nails hold it nicely in the middle. Then the mould is heated, the 3D print melts out – so it’s lost – and that’s where the space for the bronze remains.
Casting is a fascinating process, an archaic game of heat, precision, and speed. Bronze is heated to around 1100 degrees Celsius – in a crucible that can withstand this heat, even if it glows. Embedded in the floor of the casting room, all the prepared moulds are placed in sand, with the filling holes upwards. The sand provides stability and absorbs the pressure the heavy and hot metal puts on the forms.
Black patinated
The casting works: the figure removed from the mould is flawless. Bründler spends some time with the final polishing: the nails must be removed, and all traces of casting on the figure have to be sanded off. It is noisy in the workshop. Bronze is too yellow for me in the original, so we patinate it to black. This happens in several steps of applying copper nitrate and heat.
Limited small sculptures
One of the 3D printing companies I approached told me about the possibility of printing figures in spruce or beech. This involves processing sawdust with the lignin contained in the wood into long spaghetti and rolling them up like cables. These then feed the printer, which heats the whole thing and meticulously lays it down layer by layer on a plate. Where this laying down comes to nothing – for example, at the mobile phone arm of the «Selfieman» – the printer lays down a loose but stable framework. This is then meticulously removed manually.
I had «Farsight» and «Selfieman» printed in fir, the 16 cm high figures would even be edible in their original form. In a longer process, I found a way to give them their character with pigments – as a limited series of six copies each.
Read more:
«Sculpting live» shows the making of «Selfieman» in wood.
«Balance: out of gratitude» tells the story of this series.
All my Art Stories about sculptures, wood, and commissions.
