Monday, March 31, 2008

Sonic Fabric

I found this video by Alyce Santoro - cool to hear the sound the fabric makes when a cassette is run over it playing in the background as the soundtrack in the beginning of the video. The Fresh Design Ideas blog took to me the sonic fabric website where I read that Phish percussionist Jon Fishman wore and "played" a sonic fabric dress on stage so I wanted to find a video on this because I was half expecting to hear actual songs played. I had to know for sure what kind of "music" the fabric can "play." Turns out it's not actual music, but funky sounds that made me think of martians. Very cool.

Saturday, March 1, 2008

Lost Wax Casting - Steps with Pics

(wax pattern)

1. The figure is carved in solid wax by the sculptor (in this case, M. A. Dabritz). This is called the "wax" or "pattern".

(wax pattern with casting sprues)

2. Sprues (wax "wires") are attached to the pattern. These will burn away to form channels through which the wax leaves the mold and also through which the molten metal enters it.

(ceramic mold made from investment - cut-away view)

3. A ceramic slurry ("investment") is poured around the wax pattern and allowed to harden around it like plaster. This surrounds the pattern completely, the picture shows a cut-away view so you can see what is happening on the inside of the mold.

(ceramic mold after wax evacuation - cut-away view)

4. The wax is "burned out" in a kiln at 1250° F (orange hot), so that it goes up in smoke and leaves its impression in the ceramic. This creates the mold. Hence the term "Lost Wax" because the wax is gone.

(picture is taken with a flash so that you can see the cylinder that used to contain the wax pattern, before it was burned away - now it is the mold into which the metal is forced)

5. Metal is melted and to be forced into the cavity left by the wax.

(unfinished bronze figure with sprues - just out of the mold)

6. The hot mold is plunged into cold water to disintegrate the investment so that the bronze figure(s) can be removed.

(finished piece)

7. The metal figure goes through several finishing and polishing steps to complete it.


Lost Wax Casting

Lost wax casting, also known as cire perdue (French for “lost wax”) is a method that has been used for centuries to make many of the intricate metal objects we see in museums today.

“People used this technique all over Europe, Asia and North Africa. It was used by the Sumerians in 2500 BC when bronze was first discovered. It was then used in Shang Dynasty China (1700 BC) to make goblets for sacrifices to the gods and in medieval Europe (1200 AD) to cast the bells for the cathedrals. Lost-wax casting seems to have been independently developed in West Africa around 900 AD, too.”

Lost wax casting is used to make objects in metal that can’t be made any other way because of how complex the form is. Wax is used to make a model of whatever object you want to ultimately be made from metal.

Wax models can be made by hand and then cast to make one object or a mold can be made to produce multiple copies of the same form.

Once the wax model has been touched up and is ready for casting, the first step the form undergoes (and the most important) is spruing. Spruing is a process in which sprues (wax rods) are permanently attached to your wax model which will provide paths for molten metal to flow and for wax to escape.

The sprued model must then be secured to the bottom a steel tin flask, keeping in mind that there must be ample room between the model and the walls of the can (about a half an inch from the top and a half an inch on the sides).

The next step is pouring in the investment. Investment is a type of plaster that won’t burn or crack when subjected to the extremely high temperatures that molten metal can get up to. The investment is mixed with water to form a slurry which is poured into the can to completely submerge the wax model.

The can with the sprued wax model and the slurry is placed in a debubblizer which sucks the air bubbles up to the surface of the investment so that when the model is cast there won’t be any cavities formed by bubbles.

The can is placed in a kiln to undergo the burn-out process. After this, all that remains of the original model is a negative space inside the hardened investment. Now molten metal can be injected into these spaces in the investment that were once occupied by wax.

Once the injected metal hardens, the cast piece must now be released from the can. This can be done by hammering or sandblasting the investment away.

The final cast piece will be dull and have many imperfections. The last process then is to polish the piece.

Since I have not actually cast something yet, I’m not sure if what I have written here is correct. This is a summary of my notes from class, some books and some websites on lost wax casting. As the semester goes on and I learn more about casting, I will edit this post.

5. Modeling in Wax for Jewelry and Sculpture, 2nd Edition by Lawrence Kallenberg

Blood Diamond Pics

Blood Diamond Research

Diamonds that fund devastating civil wars, diamonds used by warloards and rebels to buy arms, diamonds associated with bloody violence, human rights abuses, terrorism, and environmental damage - these are blood diamonds, also known as conflict diamonds.

They have funded conflicts in Africa that have displaced and killed millions of people. These illegal diamonds have also been used by terrorist groups like al-Qaeda to finance their terrorist activities all over the world.

Workers in the blood diamond trade are subject to exploitation, brutality, poverty, dangerous working conditions, torture, maiming, and death. Many workers are children, unprotected by any child labor laws.

Legitimate or fair trade diamonds, which promote community development and higher incomes for diamond diggers, are supported by the Kimberley Process, where member countries pledge not to import or export conflict diamonds, as well as by organizations such as PRIDE Diamonds, a socially responsible mining organization in Sierra Leone.

However, blood diamonds are still being smuggled into the diamond market, as the diamond industry has failed to create an auditable tracking system with a solid chain of custody to ensure that diamonds are conflict free.

1. Blood Diamonds and How to Avoid buying Illicit Gems, John Roach for National Geographic News, Dec 8, 2006,
2. Website for Stop Blood Diamonds, an organization pleadged to stopping the exploitation of the diamond trade by human rights abusers,
3. Website for the World Diamond Council,
4. Wikipedia on Blood Diamonds,
5. Website for the Conflict Free Diamond Council,
6. Webiste for Global Witness, the first organization that sought to break the links between the exploitation of natural resources, and conflict and corruption,
7. Website for Brilliant Earth, Conflict Free Canadian Diamond Jewelry,
8. Website for United Nations,