The first thing I did was videotape a rabbit hanging out on a lawn.
I got more than half way around him, so I could print out lots of freeze frames to work from.

I roughed in his overall shape and dimensions using plastilina, an oil based clay which doesn't set hard or need wet rags to stay pliable.

The early stages look rather weird and creepy.
Like killer zombie rabbits from outer space.

I can tell they're coming along nicely when my wife Meridee talks to them on her way past.

Once he was more or less done I made his final ears...

...and put him with his friends.

Once at the foundry they have to make a rubber master mold, from which they cast many wax replicas of my original clay rabbit.
Each wax replica will have a hard ceramic mold or shell made for it, and the wax replicas eventually become bronze.
Then the hard shells are broken off each one.
The following description is rather non-technical, but will hopefully give you the general idea.
It's a very sad life being a rabbit at this stage. Come to think of it, it doesn't get much better until they're finished.
Let the tortures begin...
'Off with his ears'.

The first coats of rubber are applied very thinly to pick up all the fine details.
Then thicker layers are applied.
The ears are in that tall thing.

Then a tough outer layer of either plaster or fiber glass holds the overall shape of the flexible rubber once the clay is removed.

Ede, the foundry manager, shows off Scott's finished master mold for bunny#1.

And I get what's left of my beloved bunnies once their torment ends.

Thin runny hot wax is painted inside the rubber molds. It hardens as it sets until layer upon layer become about a quarter of an inch thick.

Then the wax bunnies are popped out of their molds.
This is called wax casting.
The ears are cast in wax seperately in their own little molds and stuck back on the wax rabbits.
Any blemishes are carefully attended to by skilled artisans, which is called wax chasing.
Once they get a thumbs up from the artist, the business of spruing begins.
The small blue bits of wax that look like birthday party candles between their ears ensures that the bronze makes it all the way to the ends of the ears.
Of course later those 'party candles' will be made of bronze and need to be cut off, and the ears filed smooth.
Mmm mmm. Right now they look good enough to eat.

The rabbits are hollow, just like chocolate easter bunnies.

All the wax will eventually be replaced with molten bronze, so now channels are made with more wax to let the wax run out and the bronze flow in once the hard ceramic shell is in place.
The beams of wax sitting between the rabbits and the pyramids in the picture below, are those channels.
This is part of the sprueing process.

In more complicated shapes, more wax channels are added to ensure that the bronze flows smoothly into all the areas, like you can see between the ears.
It also prevents air and gas from getting trapped as the bronze flows into the ceramic mold.
You can see up inside the rabbits in the picture below.

So it's time to make the ceramic shell. First, the wax rabbits, with the added channels in place, are dipped into a liquid, then into a very fine sand which sinks into all the tiny crevices to capture fine details. This is called the print coat.

This is repeated several times once each layer dries.

Eventually they get dipped into the goopy stuff which completes the hardened shell, or 'investment'.
The laying down rabbit below was prepared differently to the one above; the pyramid is off to the right, just out of sight.

The hard shell coats both the outside and the inside of the hollow rabbits and the hollow pyramid, and encloses the channels between them.
The bottom of the pyramid is cut or ground away, and the piece of hard shell inside it is removed.
If it were now flipped upside down the pyramid would resemble a triangular cup with an inner wax lining.
This is called the sprue cup.

With the sprue cup facing down the whole thing is heated up and the wax is melted out of the ceramic shells, so all through the hardened shell there is a narrow space where the wax used to be. This explains the term 'lost wax method'.
The heating also further hardens the shell.
The upside down sprue cup beneath the rabbits is where the wax ran out, and where the molten metal will be poured in, so as you can see they must be turned the other way up and attached to a metal frame, along with the handiwork of other artists.

The metal frame with all the ceramic shells attached is heated on one side of the room as the bronze is melted on the other side. Heating the shells prevents the bronze from cooling too fast once it's poured inside.
The bronze is poured into the crucible: a giant bucket suspended from tracks in the ceiling. Then it is moved to the middle of the room.

The freshly hot ceramic shells are also moved into the middle of the room.

This is very skilled work. The crucible has to be manouvered around to fill all the ceramic shells while it remains at 2100ºF, and while the shells are still hot, and while avoiding any accidents.
Time is of the essence during this casting phase. It's wonderfully choreographed, although if you missed your footing you might suffer much worse than a sprain.
The molten bronze is made of 95% copper, .02% lead, .02% tin, .06% zinc, and 4% silicon.

A short while later Ian, who is in charge of these very scary proceedings, carefully lays into bunny#1 with a hammer to knock off some of the shell...

...because he left his lighter at home.

Pouring is hot work. Ian leaves work 4 lbs lighter than when he arrives on pour days.
Bunny 3 here has been carefully broken out of his shell, and had the metal channels and sprue cup removed.
The metal starts to oxidise as soon as it cools, and here you can see that it's losing it's gray color already.
He's ready for a sandblasting to remove the rest of the shell.
A little more metal work needs doing before he's patinated.
In the picuture below he's two days old.


Metalwork: Nuts are welded inside for attaching a base, or for 'capping and felting' (so he can sit flush on a nice polished table without scratching it), or to attach threaded metal rods to sink into a concrete footing if they are placed outside.
Also, any blemishes are cleaned up, just like during the wax chasing stage.

Here they are, all cleaned up.

The next round of torture is about to begin, as the poor critters are dipped, sprayed and painted with nasty chemicals as well as rubbed, attacked with a rotating wire brush and blasted with fire before having wax painted all over their hot little bodies.

Vince knows what he's doing, and this little fella even seems to be enjoying it...

You can see a partially waxed rabbit below.

No two patinas will be exactly alike, but they can be kept within a certain kind of look.

And so the cycle of life continues, as it has done for countless eons: The returned clay from bunny#3 bathes in the sunshine and adds to the frame of a large toad armature which will one day become a bronze itself.
You can see some cross sections of clay from bunny #2 laying beside the amphibious innards.

I am personally amazed by the whole process of bronze casting, and greatly appreciate the care and skill which the people at Shidoni foundry in Santa Fe put into their work.
My layman's description is just a sketch as it were, in the very broadest strokes and covering a fairly simple casting in an attempt to de-mystify the process for the curious.
There's a lot more to it than I've described, especially with more complicated pieces, but hopefully I haven't done the fine foundry folks too much of a dis-service.
They really are good at what they do. A lot better than I am at explaining it.

There's lots more stuff like this on my BLOG.
In fact in THIS POST there's 24 links to other 'How to' posts I've made.

Click below if you want to...
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