"Tufa Casting"

    Tufa (too'-fah) is a soft, porous, chalk-like material (essentially limestone).  It is formed as underwater springs rich in calcium mix with lakewater that is rich in carbonates (as in baking soda).  A chemical reaction occurs, resulting in calcium carbonate - limestone.  Over decades to centuries, a tufa "tower" forms underwater.  Tufa is found today in dry lakebeds.    The photo at left shows tufa in its natural state.  A saw is used to cut the tufa into a block and a design is carved into it, in this case, a naja. (Photo below...)
       After applying a coating of carbon to the design to ease removal of the casting, the tufa is clamped together with a "blank" cover piece as shown in the next two photos...                                       

 
 

 


 

    Scrap silver is then melted down and poured into the mold......

 

 

 

                                  Below you see the casting as it is in the mold.... after it has been "cleaned up" and filed...and finally the finished piece!  (See more naja designs here.)         Back to Techniques