Lost Wax Bronze Casting

Cari Amici (Dear Friends),

I recently got the opportunity to cast bronze in Austin, Texas, at the Atelier 3-d with artist and teacher Steve Dubov. Always interested in process, Steve uses a different kind of investment mold and alters his technique for the lost wax bronze casting method.

So, I created a couple of new sculptures in wax. In my art post on April 15, you saw an image of me creating the sprue, the wax sculpture connected to a wax funnel that will all ultimately become bronze.

While I need my wax welds to be strong, these things are a bit fragile and oddly shaped, each sprue being individual. My bumpity dirt driveway that is almost a mile long helps nothing. So, I have transported the wax floating in a bucket of water. This greatly diminished the vibration and shock on the piece, although I still had water sloshing around in my car. Sheesh, I must continue to fill the driveway potholes with stone chips!





In this third image, air conditioning metal tubing has been used to create a “mother mold” (the outer supporting mold). I am holding my sprue to keep it from floating, pour funnel at the top opening with the sculptures deeper, parallel to the side walls. Steve is pouring a mixture of plaster, playground sand, and water into the mother mold. Once this mold has set, holes will be lightly punched into just the metal tubing to release steam later during the pouring of the molten bronze.


After the mold is ready, it will be heated and all of the wax will be melted out. Now the sculpture is then only an air space. Bronze will be heated to about 2000 degrees F so that it becomes a liquid. Then it will be poured into the funnel-shaped opening, travel down the air space, follow the sprue space to fill the sculpture space, and then chase air out the vents. The bronze begins cooling as soon as it is poured, so everything in the pour moves fairly quickly.

I did not attend the bronze pour since I was working in my studio on my stone carving. This fourth image shows you the bronze pieces after Steve cut away the mold and then cut apart each sculpture from the cooled bronze sprue parts. He left some of the sprue on so that I could put the art into a vice as I chase the metal.


“Chasing” means cleaning up all of the metal sculpture so that it looks as I intended. This often means grinding off all sprues and vents and re-sculpting those connection points as desired. On larger artworks, “chasing” also includes welding all parts of the sculpture together, and then grinding out all evidence of the weld in the visible areas of the sculpture.

In this last image, you may see that the investment mold cracked and allowed bronze to leak out beyond the sculpture and into the crack. It is too bad that I did not plan ahead for this… this bronze has a cool pattern. It is a bit nautical, like a merman’s fins, eh? I also like this photo because of the way the light is bouncing off of the various facets that I carved into the original wax sculpture. One of the things I enjoy about bronze is the ability to create a texture that is quite different from what I can create in stone.


This is likely to take me days to clean up to my satisfaction and later add a patina to my new sculpture. So, stay tuned . . .

*******

Please join me on Sunday in Austin, Texas, for the release party for Origin Magazine. Origin features articles about quality living, such as yoga and fine art.


Whole Foods Rooftop Downtown Austin,
5th and Lamar
Sunday May 1st, 2 - 6 p.m.

Art, Music, circus, One of the largest Free Yoga Classes ever held in Austin led by National Teacher Christina Sell at 4 p.m. Costumes welcomed, Performers, Artists, Sponsors, Vendors, Connection, Celebrating 152 pages of Art+Community. We are debuting the same issue in 6 cities within 3 weeks. WOW! Djembabes play at 5:30pm.

This issue features 60+ artists, 90+ yogis and 152 pages of art, philanthropy, beautiful photography, conscious articles and a lotta love. It’s all free!
For more information, contact Maranda Pleasant at: Editor@originmagazine.com.

Lost Wax Bronze Casting

I received a wonderful gift this month. A new collector with a vision and trust is helping me to realize one of my most personal artworks in bronze. I first created “Against the Dying of the Light” in 2001. I originally sculpted most of the clay in a week in my Texas studio and then later added the large hands at night at my site at the MARBLE/marble Symposium in Colorado. After I returned to Texas that summer, I hired several different models to assist me in getting details such as the veins in the arms and, as I told one model Todd, “quads like diamonds.”

For various reasons, this sculpture was put on hold and finally finished in 2005. Then in August 2007, a mold was made. While I had received wonderful comments and several inquiries about this sculpture, it was only while I was in Italy this past fall, that a serious collector contacted me. So my foundry created the wax from my mold in time for me to arrive back in Texas and work the waxes that will later become bronze.

For those unfamiliar with the bronze casting process, most bronzes are created hollow, like a chocolate bunny. Smaller pieces can be cast solid, but if very thick, that is not practical. Not only because of the ever-increasing price of the metal, but mostly because of the chemistry of cooling molten metal. Bronze is poured into a mold when it is around 2000 degrees hot – after the metal has become a beautiful liquid. Thin sections cool faster than thick sections, and this unevenness, if you will, causes problems in “shrinkage.”

In the case of “Against the Dying of the Light,” the arms will be cast separately, and solid. The upper body will be cast hollow, but as its own piece. And the hips and legs of the figure will be cast as one hollow piece with the large hands. After the sculpture has been cast into bronze, the parts will be welded together and then “chased,” resculpting details in the metal where all the connected parts require it. Then I will add the patina and carve the stone base.

Here you see my original work in plastilina (an oil-based clay) and later the wax pieces that my foundry poured from the mold that was made from the plastilina original. I am spending this week “chasing the wax” or removing mold lines, bubbles or holes in the wax, and checking that every detail is true to my original idea. The first step I do is examine the wax and thicken thin parts. My goal is to have a wax of consistent thickness, to minimize the effects of bronze shrinkage after the pour. It is difficult to pour a hollow figure, and often (internally) protruding parts (receding parts in the outer surface) must be reinforced from the inside. (One image shows how transparent the wax looks in the crotch area of the figure. I can clearly see where the wax is too thin.)

I will finish these waxes and return them to the bronze casting foundry before I return to Italia soon. I cannot wait to see “Against the Dying of the Light” in bronze!