Thursday, March 7, 2013

Surfaces: Ancient and Contemporary

    It’s easy to dismiss traditional methods of metalworking as primitive and crude in light of the incredible advances in materials processing techniques both on the industrial scale and at the level of the humble craftsman.  However, now that environmental consciousness, reduction of the use of harmful chemicals, materials recycling, and other altruistic values have become fashionable, the methods of the ancient metal caster have once again become contemporary.  The use of clay over resin bonded sand and natural oils and solutions over complex chemistries now give these methods an advantage over what was considered to be “advanced” techniques.  My focus for this course is to investigate and experiment with methods of surface treatment and patination of cast metals used by ancient craftsmen and try to integrate those techniques into my own work.

    The patterns I designed for myself are geometrically simple so I can focus on the surface of each piece.  I molded two patterns out of wax and molded each in dung and clay.  They were both cast in bronze.

Bronzes from Dung Molds

    In keeping with attempts to use both contemporary and contemporary methods of making, I used 3D modeling (Rhinoceros 3.0) to design a sweep for the Japanese Sogata technique of making vessels.  I enjoy the idea of using such a technologically sophisticated technique and traditional mode of making in tandem.

Sogata Mold and Rendering

    My research into surface techniques has been fruitful.  Not many sources look at surface treatment and patination of metals with a historical perspective, but I was able to get my hands on a copy of “Metal Plating and Patination: Cultural, Technical, and Historical Developments”.  The title says it all really.  This is a must have book for anyone looking to do serious research on the topic, or a very good place to jump off from.  From the articles in the text I was able to come to some broad conclusions regarding the nature of surface treatment in ancient times.  The following is a dilution of the information I was able to glean from the above book.
  1.   Metals were not often patinated deliberately in pre-classical times: By this I mean that the method of patination we are accustomed to today, with application of solutions that quickly alter to color of the metal, were not in use.  The Romans were quite fond of polished bronze as a finish, though were well aware of the tendency of bronze to acquire a different color and surface with time.  Many of the first hand accounts of techniques of the time come from Pliny the Elder, who details some techniques for protecting the surface of bronze.  In western culture, it was only during the Renaissance that patination became a standard, and that was simply to imitate the state of Greek and Roman bronzes rather than to innovate new colorations.  At that time, and long before, the natural color of bronze was considered to be black, so it was a very popular surface to emulate. 
  2. Patinas were influenced primarily by metal chemistry, and not surface treatments: This detail was quite shocking for me to learn, as it seems counterintuitive, but realizing that the production of alloys in the first place was a craft lends credence to this.  Nowadays, we buy industrially produced alloys, which, by nature of the industrial system, limits what is available to us.  Ancient metal casters suffered no such restriction, and could pay for and request certain alloys to achieve the results they desired over time.  Silver and gold were popular additions to copper alloys, as they would cause a purple-black patina to occur with the right chemistry.  This is especially true with the Japanese, who pioneered still famous alloys like shakudo (a copper alloy with gold additions) and shibuichi (a copper alloy with up to 25% silver added).  This brings me to my next point…
  3.  Of all known cultures, the Japanese have the most prolific and well documented tradition in the coloring of metals: The pure range of colors they were able to achieve by changing the alloy chemistry is amazing and, counter to my comment earlier, they pioneered chemical surface treatments of all kinds.  These techniques are still in use and produce rather stunning results.

    My intention from this point forth is test select treatments from disparate cultures and document the results and the ingredients used.  My creation process will be designed so that mass production is possible and I can move to the metal finishing process quickly.  The next form up in line is a rams horn, which I'll take a mold of and make as many as I can.  Stay tuned for more!

No comments: