Glass - Back to the Future!



Presenting Author:
Stephen P Koob
<koobsp@cmog.org>

article posted 15 Dec 2015


Stephen P Koob received an MA (1976) in Classical Archaeology from Indiana University, and a BSc (1980) in Archaeological Conservation and Materials Science from the Institute of Archaeology, University of London. He spent 5 and a half years as conservator of the Agora Excavations with the American School of Classical Studies in Athens, Greece. From 1986-1998 he worked as conservator, specializing in ceramics and glass, at the Freer Gallery of Art and Arthur M. Sackler Gallery, Smithsonian Institution, Washington, D.C. In 1998 he came to The Corning Museum of Glass, where he is now Chief Conservator. He also continues teaching archaeological conservation at the site of Samothrace, in northern Greece, and has numerous conservation interns at Corning. He has recently published a book, "Conservation and Care of Glass Objects" .








Materials and Techniques for Filling Losses in Broken Glasses

Stephen P. Koob
Chief Conservator, The Corning Museum of Glass, One Museum Way, Corning, NY 14830, USA


Losses in glass can be very difficult to fill and there are numerous options for materials and techniques. It is almost impossible to reheat damaged glasses and use hot glass for repairs and restoration, so the conservator has to rely primarily on synthetic resins. Over the past 50 years, epoxy resins have become the material of choice for repairing damage and for filling losses. New developments in casting and moulding, as well as new techniques of application, provide the conservator with easier and more successful results. Indirect castings, such as detachable fills, also pose less risk of damage to the original glass, and are also much easier to redo, should the fills need to be replaced over time, usually as a result of the epoxy yellowing.

Acrylic resin fills are also very useful for filling losses in certain glasses, especially thin, archaeological glasses that need to be handled as minimally as possible. New techniques for casting stable acrylic resins, such as Paraloid B-72, sometimes provide a better alternative than using epoxy resins.

Some additional materials, such as mixtures of wax and resins, can also be successful as fill materials for hard-to-imitate glass surfaces such as Tiffany glass.

Whatever materials are used, patience, manipulation, and control of the materials used is critical to making effective and accurate restorations.