ART AND GEOSCIENCE OF PIETRE DURE – FLORENTINE STONE MOSAICS

This presentation describes the process of researching, designing and creating a Florentine stone mosaic or Pietre Dure (hard stones) based on the traditional methods of Italian stone inlay craftsmanship, but using softer stones and modern technology. This credit-bearing project by an undergraduate student majoring in Studio Art and minoring in Geosciences aimed at exploring connections between geology and Pietre Dure with the goal of evaluating their usefulness in geoscience education.

Inspired by the traditional motifs of birds and the appearance of stones donated by a local distributor, a ruby throated hummingbird was designed. The hummingbird drawing was divided into 16 sections incorporating 12 different kinds of stone chosen for their color and texture. Petrographic thin sections were made to provide geologic information (i.e., age, formation, composition, texture) about the stones used in the mosaic and to investigate how their origin and properties played a role in their selection.

The design was printed on transparency paper and cut into individual pieces, which were placed on cut and polished stone surfaces to help choose the areas for the hummingbird design and to guide stone cutting. The project also involved making and testing of a traditional wire bow saw, but the stones for the final mosaic were cut on a computer controlled OMAX waterjet after a chipboard prototype was made with a laser cutter. These modern technologies required the original drawing to be traced using AutoCAD and CorelDRAW, respectively.

The cut stone pieces were glued to each other and onto an aluminum background plate using EpoThin 2 epoxy. After drying, the mosaic was hand polished to remove extra epoxy and flatten the surface using grit sizes 100, 180, 220, 400, 600 and 1000. The mosaic was then buffed with a hand-held diamond pad polisher, and coated with Ager Tiger to seal and enhance its color and shine.

This endeavor provided unique insights into the traditional methods of making stone mosaics, and ideas for modifying conventional practices to suit modern technology and available materials. This was in part accomplished through consultation with experts from a restoration lab in Florence, Italy. The project concluded that creating Pietre Dure can be an engaging and effective tool in learning and communicating geologic information.