Kovács Petronella (szerk.): Isis - Erdélyi magyar restaurátor füzetek 1. (Székelyudvarhely, 2001)
T. Bruder Katalin: Kerámiarestaurálás I.
decreases the binding properties of casein and eggwhite. It can change the colour of some pigments with lead and tin components. The application of the above listed gases has partly been or will shortly be banned due to their strong poisonous properties. At the same time, the use of inert gases - nitrogen, argon, carbon dioxide - has become more common. In the case of nitrogen and argon, no deteriorating effect has so far been observed on art objects. Carbon dioxide used in an environment of high humidity can cause changes in the colour of some pigments, the transparency of linseed oil varnish, gum arabic and shellac layers because of the development of carbonic acid. Fumigation is carried out in well isolated containers, chambers or in impermeable foil tents. Traditional foils (e.g. polyethylene) are inappropriate, only special, so-called laminate foils made of several layers are suitable. Foils containing a polymeric or copolymeric sealing layer of ethylenevinyl-alcohol, chlorine-trifluor-ethylene, chlorine - vinylidene or acrylic-nitrile (propylene nitrile) can be effectively used. Gas containers of liquid nitrogen or a nitrogen generator can be used as nitrogen sources. Oxygen can deteriorate art objects. The Ageless® product (with finely pulverised iron (II) oxide as agent) can be used for protection due to its oxygen absorbent property. It helps to reduce the oxidation of metal objects, the ageing of art objects made of organic materials, the growth of aerobic microorganisms and the damage caused by insects. The packets of Ageless® sold in commercial circulation must not be placed directly on the objects since in consequence of binding oxygen in exothermic reactions, the packet becomes hot. Ageless® can be combined with Art-Sorb, which helps to set the humidity of the air in the packet to the necessary value. RP System TM is a system that binds oxygen and deteriorating materials, which has more use than disinfection, it also protect art objects against oxidation and corrosion. Vital abilities of insects cease on a low temperature, while in a temperature higher than optimal (usually above 50 °C) they usually die of heat. In the case of art objects disinfection with heat can only be used if it can be solved that the humidity of the object does not change during the treatment. Fungi also survive only within limited temperatures. From the respect of protection, it is important to know the temperature at which their mycelia die. It is usually between 40-60 °C depending on the species. Freezing is not effective against fungi, but it can be applied in the case of insects. They can be killed within -14 and -20 °C. Dr. András Morgós Chemist, wood and furniture restorer artist Magyar Nemzeti Múzeum Head of department of conservation Dr. András MORGÓS Solidification of damaged wood Different methods are needed to solidify damaged wood depending on the quantity of water trapped in the wood. From the respect of water content, wood can be divided into two main categories: water logged wood or wet wood and dry wood. In the first case water fills in the walls of the cells (bound water) and partly or entirely the cell cavities (free water), while dry wood contains only bound water. The microspaces of the cell walls originating from the biological structure of the wood or from damages caused by fungi can be filled in with materials of small molecules that fill in the cell walls. The methods of filling in the cell cavities aim at the prevention of the collapse of the cells and the increase of the mechanical properties of the wood. The solidifying agents substitute the free water of the cell cavities in the case of wood saturated with water, while at dry wood damaged by insects or fungi, the materials that fill in the cell cavities build a new interior solid skeleton within the wood structure. One has to be careful at the solidification of wood that the solidifying agent does not change the colour (invisibility) of the object, if possible, it should be irreversible and have sufficient solidifying properties. The possibility of the repetition of treatment and the aesthetic appearance of the wood surface are important aspects. Before treatment, the type of damage - caused by fungi or insects - must be determined. Consolidating resins are usually applied in a diluted state. The molecule size of the resin is the most important factor from the respect of consolidation. The solvent influences the permeation of the solidifying agent. Polar solvents swell the wood fabric and thus prevent deep permeation. Quickly evaporating solvents result in the accumulation of the resin on the surface. According to chemical classification, the consolidating agents can be acrylates (Paraloids and Acryloids B66, 72, Elvacite 2013, 2044, 2045, 2046), poly(vinyl acetate)s or poly(vinyl butyrate)s (Butvar 72, 76, 98, Mowital B30H, B60H). The consolidating agents can be transferred into the wood through the butt-edge with impregnation using high pressure ampoules, with injection, with boring holes, or with impregnation using vacuum or vacuum and pressure alternately. It is suggested to preclimatise the object in 50% relative humidity and carry out solidification in 15-18 °C watching the appropriate prophylactic instructions. Dr. András Morgós Chemist, wood and furniture restorer artist Magyar Nemzeti Múzeum Head of department of conservation 95
