When the cast piece is complete, and the sprues are cut-off, there remain scars where the grinder or saw was used. These areas need to be finished to match the look of the rest of the surface. To chase, is a metalworking term, to ornament metal by engraving or embossing. From this:

To this:

Just mess it up with chisels, punches, files, hammers, stones, whatever, it don’t try too hard to make a match of the texture. It’ll look fine when you heat the spot with a propane torch, which darkens the metal by oxidation I guess.

I leave it all outside for several weeks, and I spray it down regularly with a teaspoon of cupric nitrate mixed with 12 oz water.

..and it slowly turns this nice color. This is patina.

When I’m ready to commit to the patina, I give it a light wax to stabilize and protect it. This darkens and warms up the colors, and brings out the shiny highlights both at once. Real nice.

A and Q supply a nice rock for a base, and Eureka! It is finished & ready to show.

October 4 – November 1, 2013

Main Gallery: Joyce Brienza & Matt De Genaro
Opening Reception: Friday, October 4 – 7pm – 9pm

Paint Creek Center for the Arts
407 Pine Street
Rochester, MI 48307

Gallery Hours: Monday – Thursday 9am – 9pm, Friday 9am – 5pm, Saturday 10am – 4pm

And so, I’ve arrived at the final sprued and vented wax, complete, ready to encase in ceramic slurry and sand, the next step of preparation for the pouring of bronze.

These are the materials which make the shell. Colloidal silica slurry mix, and refractory silica sand. You dip the piece into the slurry, and sieve the sand onto the wet surface. Repeat up to eight or twelve layers. This work is taking place at “H”’s studio foundry, a place well-equipped for this. I’d not be able to do any of this without his generosity in sharing with me his superb facility, and his supportive help and advice. (Thanks)

I’m doing half the piece at a time since it is large enough to not fit in the bucket of slurry at once. It has been very warm here this past week, 90+ degrees, and as strong as I’ve tried to make the sprue system, the piece is moving and settling a bit. I want to get this solid shell going on it as fast as possible. There is a lot of difference in the way the wax behaves between 70 and 95 degrees. The first and later layers – green when wet and orange when dry. I’d rather be doing this in Winter, but I’m committed.

This is maybe three layers. many more to go, until it is solid enough to support the weight of the bronze eventually going into it.

Something else I’m doing also, unfinished from a while back. beach Stone people

Is this taking a long time? (I did go to the beach for 10 days). It was a year ago tomorrow since I completed the model for this sculpture, but for details.

A year.

A sprue is the passage through which liquid material is introduced into a mold. A system of sprues is designed to deliver metal to all areas of the mold evenly and quickly. Bronze has shrinkage as it  cools; A sprue can continue to provide molten metal to the casting, provided it is large enough to retain its heat and stay liquid, as metal in the main casting cools and shrinks.

I prepared four waxes to sprue up. I may try different arrangements and discover which work best. This is especially crafty work. There are a variety of ways that this is done, superstitious and occult, and I wish there were more people to consult about it. Much of the shop talk in a foundry is on this subject.

The instinct is to start in attaching wax rods to the obvious points where the cleanup of the sprue marks on the final bronze will be easiest, and joining them up at some single location which will be the pour cup. But working this way can make a weak and fragile system. It has got to be strongly integrated with the sculpture, and really there is no way that an attachment point of wax merely melted together will hold the weight of the sprue system through all the handling that going to follow. No, not this:

What is needed is a self supporting structure which can bear all of it’s own weight, and further lend support to the sculpture. Something like your hand securely holding onto something delicate.

Your hand is the strong thing; the sculpture the delicate. Build something as if from the wrist, being the common point where the pour cup will be, to the hand, where the fingers are rooted from, to the fingers, which aren’t glued to the thing they hold, but hold/grasp onto it by virtue of their placement alone. Like this:

Here’s how. Warm up a pot of water to gently warm, not melt the rods you’re using. Pliable, but not soft. This is lukewarm or body temp water.

In this case I’m using the largest diameter rods I can, (to move metal into the mold fast and to be a strong structure), sometimes larger than the attachment point allows. Flattening the rod into a oval allows it to be fitted onto a smaller spot while keeping its same volume. Shape the rod to the piece, directly and without angles. The liquid metal wants a smooth path to follow, without creating turbulence.

When you have it right, dunk it in cold water to hold that shape.

Your shapes good? Outline them on paper so when you do the next one you’ll have a template to follow from. Save a lot of time later, especially years or next week later, when you can’t remember anything.

Assemble these together. Not by trying to melt then together with a soldering iron or whatever, but by taking some of the warmed-up wax you have and really shaping a physical joint that makes them one piece. This is sculpture in itself. Isn’t everything?

Cool this assembled sprue system in water. It should be strong enough to stand on it own, and then some. Wrist, hand, fingers.

This super-strong thing will then be integrated with the sculpture. A hint: those connection points will always be weak points of attachment. I enhance them with small pegs I make by cutting a small wax rod to size and inserting it into a melted hole I made with a soldering iron. Later I will melt another such hole into the piece and the rod (it just happens to be red wax) will support the connection much better.