The Laboratory for Scientific Restoration of Precious Metals (LSRPM) of the State Hermitage Museum was established in 2004. A characteristic feature of the workshop is the use of modern scientific and technological achievements and the Laboratory is equipped with the latest restoration and jewellery equipment.
Today, laser welding and laser cleaning of works of art have become routine techniques which are successfully used in the restoration of masterpieces in museums around the world. Thanks to modern laser technology it has become possible to restore unique exhibits, including the ones made of precious metals, which were in a poor state of preservation and previously could only be preserved by traditional methods such as gluing, tin soldering, etc. in order to strengthen the parts and not to disintegrate them further.
The State Hermitage Museum became the first museum in Russia to use laser welding of the latest generation in restoration, meeting all the museum requirements and allowing welding of the most complex parts, from the finest filigree to thick-walled objects. Unique units with welding and laser cleaning parameters adapted for restoration were developed especially for LSRPM.
Among the advanced technologies used in the restoration of exhibits note should be made of the use of advanced polymers, 3D modelling and rapid prototyping, as well as sub-proportional electroforming.
The Hermitage collection of gold and silver antique, medieval and oriental ornaments is one of the best in the world. Miniature items are made of the finest gold and silver wire, sometimes fifty microns thick. Many items require urgent restoration.
Only now, thanks to long-term research to create test patterns and software for laser welding of metals of all types, it is possible to recover this jewellery.
In order to restore the fragile items the decoration of which uses mineral paints, pearls, enamel, feathers, fabric, mastic compound and other organic materials, the Laboratory staff uses laser welding which allows restoration of the museum objects without detaching stones and breaking down organic materials.
The Laboratory uses three types of units: with fixed working chamber, with industrial open lasers, and with fibre-optic cable. Mobile systems for movement and suspension are also used.
Fibre-optic cable allows restoration work at a distance of 3 to 10 m from the unit. The machine can not only remove dirt with direct light, but also with reflected light using a special mirror. Lasers are capable of removing tin, copper, iron oxides and evaporating almost any organic layers which sometimes cannot be removed by conventional chemical reagents and are totally harmless to the exhibit. The unit allows cleaning of a dirt layer five microns thick without damaging the metal base. The use of laser welding and laser cleaning in the museum restoration can dramatically reduce the time of restoration and significantly improve the quality of work. In order to restore exhibits with enamels, the experts use reversible ceramic-reinforced light-hardening composites. Especially complex enamel inserts are restored in glycerol using high-pressure machines.
All restoration processes are documented using digital cameras and video equipment. Almost all the microscopes have built-in digital recording devices connected to a computer. In order to carry out visual control, the restorers use ocular-free stereo microscopes, stereo magnifiers and 3D video microscopes. This technique can improve the quality of restoration measures and expands the range of capabilities of a researcher.
The Laboratory staff successfully restores museum collections, treasures found in the ground and archaeological complexes. When restoring these complexes, restorers enrich their knowledge and get an indispensable restorative experience. This experimental experience is especially important in the development of new technologies, such as laser cleaning of materials.
Research is of great importance. An exhibit is scrutinized prior to restoring. Imaging units, X-ray equipment, electronic and 3D microscopes, XRF analyzers of metals and coatings, as well as other physical and chemical studies are used for this purpose.
Art restorers who have mastered most of the up-to-date jewellery techniques work in the laboratory. They conduct workshops at restoration exhibitions and in museums, improve their knowledge in archaeological expeditions and study the best museum collections. They participate in international conferences and seminars, conduct internships for specialists from other museums, and collaborate with universities and research laboratories in America, Europe and Australia.
Many aspects of restoration of precious metals are being developed experimentally. Facing complicated restoration cases and large complexes of objects, experts gradually develop their own techniques which will further help to solve various problems.
