Break outs

Casting in bronze is a humbling experience. There is no room for hubris or false confidence. You need to be clear, work as a single mind, anticipate but not over anticipate. Like going into battle, you stay frosty, ready to respond, wary of things that could go horribly wrong, but practiced in the quick assessment and action required to still the forward motion of an "incident" , a "nonsense" and to know the difference is crucial.

Sitting at the computer yesterday wrestling with emails, the director of the foundry, Sarah, said "Are you ready to go?" "Yes", I replied. "Then let's do this while we are still fresh..."

First we set up things that require an analytical presence; weighing out the bronze, firing up the furnace, stacking and lighting the burnout kiln. Taking a look at the clock, we estimate the burnout, and melt times and then go make some coffee. And drink some water. It is one of the things I often forget. In the heat of the foundry, it is easy to get dehydrated. The swift sequencing of the many steps of pouring compresses time and I lose track of human hours as I focus on bronze hours.

We decide to pour the top portions of the two torsos first. They are fairly small and the wax burns out quickly. Astonishing, the shells are perfect. There are none of the cracks than can sometimes run along sprue vents, and edges of long planes.

We suit up. This is the part where I begin to feel my breathing change. My bandanna, (to protect my ears, thin and quickly burned if left flapping in the open(!) and my hair that can completely burn off in a wave of convection heat) goes on first. We check to make sure we have our heavy cotton shirts (duck, canvas flannel). Acrylic will melt at a low temperature and continue to burn into your skin. Shoes, leather, heavy soled are the best foot coverings. Even with the leather and fireproof gators, it is possible to step on a piece of hot bronze that can burn through a sneaker in an instant. We are taking a chance to do this with only two people. The two pourers rely most heavily on each other.
I gear up, buckle and adjust the fireproof sleeves and apron, snug so that they do not flop away at a crucial moment, but loose enough to be able to move (quickly, if necessary), adjust our masks and then pull up the gloves. The gloves are bulky and I loose the sense of my fine motor movement as the hands I know so well are lost in these clumsy mittens. I wiggle my fingers, feel for holes where the air and heat can still come in. I adjust them. I take a deep breath, realizing now, that I have been taking very shallow breaths.

Sarah takes another peak at the bronze. "Ready?" "Let's do it!"

The furnace is turned off. The preheated shell is buried in the sand. Sarah opens the furnace and we lift the crucible from the furnace. The scum is skimmed from the hot pink yellow bronze. The pouring apparatus is clamped into place and we move toward the shells. Lifting and lowering 75 pounds in unison to find optimum pouring angle. The first one goes fine. The second one has some tiny broken vents that we did not see and so we have to stop pouring and hope we got enough in to fill the mold. We place the crucible back in the furnace and recalculate the next pour.

We get the two larger pieces and burn them out. They will be poured separately to spare our backs. Each pour takes its toll in our muscles, our reflexes, our focus. The next two pours go perfectly. There is a small crack that I repair, even though it appears to be a surface crack. We do not want any more surprises today.
There is a strange bubbling in the cup, which indicates trapped air in the cast. I will remember this and be more careful constructing the next wax model.

I break out the two small piece first. And then the two bottom pieces. The above photo shows the pour cup, sprues and air vents. These will be cut off and the white residue from the investment will be picked off with dental tools and sand blasted.
the pieces have some problems where the pour was incomplete, but over all I am very pleased with the results.

It is always a shock to see how small the bronze pieces are compared to the size and weight of the casts!