Ivanova Yulia – Ph.D., The State Research Institute for Restoration, Leading Researcher.
E-mail: vostrapeppa@gmail.com

This paper deals with potential utilization of enzymes for removing of undesirable compounds evoking material destruction and distortion of esthetic characteristics of painting. Criteria of enzyme selectivity for clearing, specificity of restoration methods that should comply exact balance of conditions required for enzymes activity and security of painting are discussed. The enzymes properties are analyzed from the viewpoint of their attractiveness and undesirability in restoration. The enzymes effectivity, specificity, nontoxicity and rapid results obtaining make enzymatic clearing very attractive. This approach is more magnetic than traditional methods of clearing with utilization of acids, alkaline or organic solvents and therefore corresponds to the modern trend of minimal meddling in the work of art. However, some enzymes properties restrict their utilization. For instance, all enzymes are very labile and require high degree of purification. All enzymes can be utilized only under strict conditions such as temperature and pH. Finally, after enzymatic clearing additional steps of washing with surfactants and light organic solvents are required.

Restoration, enzymes, properties of enzymes, selection criteria, methods.

Pogorelova (Freed) Nina – Paper & Parchment Conservation, LLC, Conservator.
E-mail: nina.freed@paperandparchmentconservation.com

The article provides an overview of the reagents, materials and equipment for enzymatic treatment in paper conservation. Amylase, protease, and lipase are discussed. Although the author revues North American (USA and Canada) experience, almost all of it is well suitable for Russian conservation labs. The focus is on the practical and not the theoretical part, but the article offers a list of English-language literature where the reader can find detailed discussion on some reagents and processes, their physical and chemical properties and application in the conservation field. The author provides information on popular in United States manufacturers and suppliers of some materials and reagents, gives advice on their choice, acquisition, and storage. The article mentions some important points for drawing up a conservation treatment plan: it should be taken in consideration that an enzyme treatment might alter the artifact’s original binding, and that the buffer solution’s pH will be influenced by the native pH of the artifact. The article lists various methods of enzyme treatment: bath, gel poultice, application with a brush or a cotton swab. Also, the author provides a brief information about a pre-packaged α-Amylase poultice system Albertina-Kompresse manufactured by the German laboratory Klug Conservation and offers some literature that gives its detailed description. In conclusion, a valuable online resource “AIC Wiki Conservation Catalogs” is introduced.

Conservation, paper, enzymes, enzyme treatment, amylase, protease, lipase, trypsin, reagents, equipment, materials.

Ermakova Nina – Candidate of Historical Sciences, The State Research Institute for Restoration, Leading Specialist.
E-mail: nvl-ermakova@mail.ru

The article analyzes publications by foreign conservators on problems of removing impurities of various kinds and old restoration adhesives from museum fabrics by means of enzymes. Enzymatic purification makes it possible to soften the treatment of dilapidated textiles by temperature and pH. The focus is on the impact of a range of enzymes (α-amylase, lipase, pectinases, pancreatin, transglutaminase, superoxide dismutase) on the surface morphology, mechanical properties and color characteristics of fabrics made of natural fibers. Tests on model samples allowed to establish the nomenclature of enzyme preparations that can be recommended for use in museum conservation. The inclusion of enzymatic purification in the restoration program is limited by conditions affecting enzymatic activity: enzymes are incompatible with many chemical reagents, have limited shelf life and strict operating conditions. Effective enzymatic purification is possible only at a not high stable temperature. Currently, new equipment has been developed that maintains a stable temperature in a soft range with uniform heat distribution over the surface. Enzymes are used not only for clearing. The method based on the use of transglutaminase (the enzyme that promotes the formation of bonds between various protein molecules) makes it possible to strengthen the old silk. A new field of application of enzymes is their use in archaeology to determine the age of cellulose textiles.

Enzymes, museum tissues, removing dirt, restoration glue.

Malachevskaya Elena – The State Research Institute for Restoration, Head of the Laboratory of Chemical and Technological Research.
E-mail: elemal34@mail.ru

Khrebtova Yuliya – The State Research Institute for Restoration, Head of the Department of Scientific Restoration of Works of Applied Art.
E-mail:julia_pgr@yahoo.com

Starch adhesives have been widely used and are still used today both in the manufacture of arts and crafts and in their restoration. They penetrate deep into the fibers of the fabric, which, because of this, eventually lose their elasticity, become brittle and collapse. Therefore, during the restoration process, it often becomes necessary to remove such glue. Mechanical and water cleaning cannot completely solve this problem, besides, they cannot be applied to all exhibits to the full extent. Properly selected enzymes can help solve this problem. Enzymes as catalysts can accelerate the chemical reaction of the decomposition of glue molecules, completely eliminating or minimizing the mechanical impact on the exhibit, remove glue from the fabric structure and even partially restore the elasticity of the fibers. The article describes the results of studies on the effect of the α-amylase enzyme on aged fabrics made of linen, cotton, wool and silk glued with starch glue. For each type of fabric, the preservation of strength and elasticity was determined which is necessary for the preservation of museum textiles. In addition, studies were carried out for possible changes in fabrics structure. The parameters of the technological process for removing aged starch glue are selected. First of all, these are specific preparations of alpha-amylase, as well as the concentration of the working solution, exposure time and processing temperature. Based on the results of the research, a technique of removal the aged starch glue in the re-restoration of museum fabrics has been developed.

Enzymes, removal of aged glue, re-restoration, historical textiles, starch glue, α-amylase.

Khrebtova Yuliya – The State Research Institute for Restoration, Head of the Department of Scientific Restoration of Works of Applied Art.
E-mail:julia_pgr@yahoo.com

The article describes the experience of re-restoration of a silk banner of the early 19th century, where the alpha-amylase enzyme was successfully applied for removal the aged starch glue. During the previous restoration of the forties and fifties of the 20th century, the banner panels were duplicated on a large cotton tulle with starch glue. This method of duplication was very popular in the early-mid 20th century, many exhibits restored at that time now need to be re-restored, it makes the problem very relevant. Aged glue destroyed historical textiles so much that in the catalog data the state of preservation of the banners was characterized as corresponding to the state of preservation of archaeological textiles. It was impossible to remove it mechanically or with the help of water cleaning. The purification method using enzymes was chosen. Enzymes as catalysts can accelerate the chemical reaction of the decomposition of glue molecules, completely eliminating or minimizing the mechanical impact on the exhibit, remove glue from the fabric structure and even partially restore the elasticity of the fibers. The effectiveness and safety of the restoration was based on the results of the research work “Applying of enzymes for removing starch adhesives in museum textile restoration”. Particular attention is paid to the selection of an enzyme preparation, and a program for its testing was developed. The sequence of technological operations of the re-restoration of banners duplicated on tulle is described.

Enzymes, removal of aged glue, re-restoration, historical textiles, starch glue, α-amylase.