The Foundry in the hills

We visited in May, after a day spent with one of our Italian lighting houses. We wanted to see where the metal comes from. Not the supplier of the metal, but the place where raw bronze becomes a finished object, because in Italian lighting that transformation still happens by hand, in workshops like this one, using a process that predates the Roman Empire.

Naples, by way of antiquity

The business is 51 years old. The craft behind it is far older. The family came north from Naples, in Campania, a region whose metalworking tradition runs back through Magna Graecia, the Greek colonies of southern Italy where bronze casting was already a refined art two and a half thousand years ago. The current owner learned the trade from his father, who learned it from his father, who learned it from his. The technique they use, lost-wax casting, is essentially the same one the Greeks used. Where plaster moulds were once pieced together in sections with animal glues, silicone rubbers and resins do the job today. The tools are better. The method is not different.

How a sculpture is cast

Everything begins with a positive model, usually worked in plasticine because it never dries out. The artist can keep adjusting, keep refining, and the material holds every fingerprint of detail. From this a negative mould is taken in silicone, plaster or resin. Once closed, the mould is ready to receive the wax.

Liquid wax, melted in large pots, is poured into the negative mould and the excess drained away, leaving a hollow wax replica of the final piece with walls of uniform thickness. This matters more than it sounds. The thickness of the wax becomes, exactly, the thickness of the final bronze. Too thick and the piece is needlessly heavy and expensive. Too thin and it loses structural integrity. Judging that balance is one of the foundry's core skills, and the arithmetic is unforgiving: one kilogram of wax becomes roughly ten kilograms of bronze.

The waxes themselves are colour-coded by behaviour. A flexible green wax forms the main model, supple enough to survive being peeled out of a silicone mould without cracking. A softer red wax is reserved for detail work, retouched with hot irons and spatulas, sometimes by the foundry workers, sometimes by the artist's own hand, until the surface is exactly as intended.

To the wax model the founders attach a feeding system, a tree of wax channels, runners and vents that will let the wax escape and, later, the metal flow in and air flow out. Small spacer nails are pressed into the wax at this stage. They look like nothing, but they hold the empty cavity stable between core and shell once the wax is gone, and if this step is done badly it can compromise everything that came before it.

The whole assembly is then encased, inside and out, in a refractory mixture of gypsum and crushed brick, forming a solid block with a single opening. The block goes into an oven. The wax melts and drains out through its channels, leaving a perfect cavity where the sculpture used to be. This is the lost wax of the name, although the wax is collected and reused, so nothing is truly lost except the model itself.

The pour

Once baked, the moulds are packed in sand or wrapped tightly in cloth bands to withstand the pressure of the casting. The metal, bronze, brass, silver or aluminium, is melted in crucibles at around 1200 degrees, and the foundry judges the pouring temperature not with instruments but by the colour of the molten metal.

The pour itself is a three-person operation. The crucible sits in a metal cradle with two long rods extending from it, one worker on each, while a third skims the slag forming on the surface. In smaller foundries the crucible stays in the burner and the metal is scooped out with great ladles instead. Either way the rule is the same: the pour must be fast and continuous, because hesitation or stoppage at this moment can irreparably compromise the casting. Watching it, you understand why this knowledge takes a generation to transfer. There is no margin in it.

Once cooled, the refractory shell, now crumbly from the kiln, is broken away by hand to reveal the rough casting, and most of the material is gathered up to be used again. Every trace of refractory residue inside the piece must also be removed, because left in place it will slowly corrode the metal from within. The channels are cut off, the burrs ground back, and then the long work begins: sanding, polishing and hand-finishing until the surface is exactly what the artist intended.

No upper limit

Small pieces are cast solid. Large ones are cast hollow, in sections, then welded together with the seams polished until they disappear, often around an internal steel armature. Worked this way, there is effectively no size limit. The foundry has produced monumental sculptures ten metres high using the same process, the same waxes, the same judgement by eye.