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New Conservation Methods for Outdoor Bronze Sculptures -

Objective

The aim of the project is the development of a new type of coating designed to protect outdoor bronze sculptures from corrosion and deterioration.

Coatings designed to protect outdoor bronze sculptures from corrosion and deterioration are being tested, in particular organic inorganic copolymers (organically modified ceramics (ORMOCER)). Different substrates, untreated or with artificial patina, are protected with different kinds of ORMOCER coating and compared with corresponding samples with conventional coatings (eg wax) and with untreated samples. Artificial weathering methods are used, including exposures close to natural weathering as well as exposure conditions which accelerate the corrosion (exchange in humidity and temperature, continuous condensation, ultraviolet (UV) test, atmospheres with high sulphur dioxide content). The corrosion progress of the samples is analysed by light microscopy (LM), scanning electron microscopy (SEM) (surface and cross section), X-ray microanalysis and infrared (IR) spectroscopy. The experiments are completed by several adhesion tests and investigations of the reversibility of the lacquer as well as electrochemical measurements.
Environmental impacts on works of art accelerate their degradation. Objects such as bronze sculptures, placed outdoor and thus vulnerable against weathering and air pollution, are particularly heavily affected. Currently available coating systems have proven to have only a limited period of protection (about 5 to 10 years) which is not ideal from a conservation point of view and does not conform to what might be expected from the state-of-the-art of coating systems.

A novel attempt is made by introducing a new class of material in this field. Organic-inorganic polymers (ORganically MOdified CERamics), containing as they do combinations of properties of organic and inorganic components are modified, in order to meet the needs of conservators.

The efficacy of various types of ORMOCERs as protective coatings is tested on a large number of substrates simulating corroded bronze surfaces.

The different steps of the project methodology can be described as follows:

- simulation of bronze patina on metal substrates
- comparison of the surface conditions of samples with original objects
- cleaning/pretreatment of the samples using a variety of traditional methods
- synthesis of different organic-inorganic lacquers (ORMOCERs)
- application of the coating on samples
- characterization and testing of the coated samples to evaluate the protective effect.

The first trial applications on originals are carried out only after very broad material/scientific testing is completed. It is anticipated that one or more coatings are developed within the duration of the project.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG E.V.*
Address
Neunerplatz 2
97082 Wuerzburg
Germany

Participants (3)

Danish Technological Institute
Denmark
Address
Gregersensvej
2630 Taastrup
Nationalmuseet
Denmark
Address

2800 Brede, Lyngby
Naylor Conservation
United Kingdom
Address
Unit H3, 19 Halesfield
TF7 4QT Telford