This project aims to address the urgent need for developing sustainable solutions to the conservation of mosaics that have been removed, or lifted, from their original archaeological setting. The project is investigating and creating alternative and affordable backing methods and materials that will provide more sustainable solutions for the preservation and long-term care of lifted mosaics.

Background

A large number of mosaics in the Mediterranean region have been lifted from their archaeological sites and currently reside in museum collections, either on display or in storage. Mosaics brought to museums were often backed with materials that can ultimately be damaging. Many of those in storage are in extremely fragile condition due to unsatisfactory lifting and relaying techniques, lack of backing, poor storage conditions, and too few trained personnel to care for them.

The conservation of these lifted mosaics requires placing the mosaics on new backings that can support the weight of the mosaic with minimum deformation while holding the tesserae in place. Unfortunately, available low-cost backing methods, like reinforced concrete, can introduce potentially deleterious materials like salts and can suffer from rebar corrosion. Lightweight and more durable backing methods such as honeycomb aluminum panels, which are currently the standard in the field, can be prohibitively expensive. Thus, the backing or re-backing of thousands of lifted mosaics is a major conservation challenge in the region, where resources are scarce and costly conservation treatments are reserved for only the most exceptional artifacts. The result is that lifted mosaics, especially those in storage, continue to deteriorate at a rapid rate.

Project

The GCI is addressing this situation by investigating alternative backing methods that are (a) prepared using locally available materials; (b) cost-effective; (c) durable (non-corrosive, low salt content, etc.); (d) reversible; (e) rigid enough with respect to size of mosaics (no warping and sagging); (f) lightweight; and (g) constructed in a time efficient manner. While this study targets mainly mosaics stored without backings, the new backing methods being developed will also be useful for mosaics on display or for those which require the replacement of existing deteriorated or inappropriate supports.

Objectives

(1) Identification of hydraulic lime mortar types and formulations that can be used as backing material (mortar testing)
(2) Performance evaluation of low-cost panels in the backing system (mid-scale and large-scale mockup testing)
(3) Development of a finite-element computer model of the backing system
(4) Production of user-friendly design charts and/or tables using finite-element computer modeling of the backing systems to guide practitioners in choosing the best backing method for their mosaics
(5) Implementation of the developed backing method using locally available materials in selected MOSAIKON countries to validate the reliability of the computer model