Conservation around the Millennium (Hungarian National Museum, 2001)
Pages - 79
ATTEMPTS TO REMOVE WATER STAINS FROM PAINTED WOODEN OBJECTS USING GORE-TEX Petronella Kovács-Edit Kővári-Csizmadi We find stains on ethnographic objects and painted wooden ceilings caused by leaks quite often. After fixing these often powdery paints, in many cases the stains become even more distinctive and thus decrease the aesthetic appearance of the object. While, there are many studies1 expounding on fixing paints not containing much adhesive agents, there isn’t much literature on the removal of water stains from painted wooden objects. Paper restorers have been using Gore-tex2, this Teflon-like poly(tetra-fluorine-ethylene) covered material laminated onto different carriers and used for wetting water-sensitive materials or for removing stains since 1980. These chemically neutral, slow aging, water repellent textile products are stable until 135 °C and provide protection against water, dust, the spores of mould, bacteria and smoke, but they allow the penetration of gases and steam. They were first used for wrapping valuable objects containing organic components and for covering vacuum tables3. MECHANISM OF EFFECTS AND APPLICATION OF GORE-TEX IN PAPER RESTORATION Gore-tex vlies and Gore-tex felt are used in paper restoration because they allow the penetration of steam. They are both tetra-fluorine-ethylene membranes laminated onto a polyester base. The only difference between them is the amount of steam they let through. When wet this membrane with very tiny, 0.2-micron size pores only allows the penetration of water contained in the polyester felt in the form of steam. Examinations showed that during treatment, in a matter of minutes the relative humidity over the membrane reaches 90%, but the art object only absorbs the amount of water, which can be kept in balance with local air pressure. At a steady temperature and after reaching this balance the membrane doesn’t let any more steam through, preventing the supersaturation of the air and the condensation of steam. Making use of the effect mechanism of Gore-tex in paper restoration practice, which makes it possible to evenly wet materials, the many different structured Gore-tex sandwiches are used for removing the end-papers of book- boards4, for removing water-stains and for straightening painted tracing paper5. In some cases paper based objects are wetted on both sides, whereas in other cases they are only wetted on one side through the membrane. Wet blotting paper and then plastic foil is placed on the laminated Gore-tex followed by a layer of thicker felt or maybe a light piece of wooden panel and then light weights are placed on them. Gore-tex is chemically neutral and resists organic solvents so it can even be used for whitening. In this case Gore-tex is directly wetted through the blotting paper with the agent used for whitening6. The Gore-tex membrane can be used for the treatment of textiles as well. In the conservation workshop of the Bundesdenkmalamt in Vienna, water stains were removed from a painted shroud on a low pressure table by the help of Gore-tex.7 79
