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This article first appeared in Conservation News 71. New Approaches to Papier-mâché ConservationDescriptionCondition Analysis Treatment Timetable Conclusion Bibliography Suppliers Health and Safety Guidelines This project, the restoration/conservation of a Victorian 'Gothic Revival' papier-mâché tray, was undertaken to fulfil the requirements of BSc (Hons) Restoration and Conservation course at London Guildhall University. Scientific research was conducted at the University of Kuopio, Finland. DescriptionA 'Gothic Revival' press-moulded papier-mâché japanned tray. Presumed to be Victorian.Dimensions: approx. 82 x 61.5 cm. No indication of maker's or decorator's name or marks. This tray was manufactured using the pasteboard papier-mâché method, first patented by Henry Clay in 1772, in which sheets of thick paper, saturated with flour and warm glue, are placed on top of a mould. After the addition of each layer, the article is pressed and dried, repeating the process until the required thickness is obtained. Then the paper surface is smoothed and several coats of lacquer are applied. ConditionSlightly dirty (dusty and greasy); missing areas around the rim; paper slightly delaminating on the broken areas, but otherwise the tray seemed to be structurally sound; small losses to the japanned surface both to the front and back. A layer of thick black paint covers the original decoration; it is possible to distinguish areas of bronze, green and red paint underneath.AnalysisTo investigate the condition and existence of original decoration, cross-section samples were taken. Despite the limitations of this technique (it provides information only of that particular spot) six cross-sections were taken from the tray. Valentine Walsh's EasySections kit was used for the sample mounting. The cross-sections confirmed that the original black japanned surface was covered with a layer of black paint. It was quite difficult to take cross-sections from the object as the japanned layer, the paint layer and the paper core delaminated from each other very easily, and the japanned layer would turn into brittle dust when subjected to pressure from the scalpel.To confirm the nature of the original finish on the tray some IR testing was conducted. The tests were done on a Perkin-Elmer 983 Infrared Spectrophotometer at the Department of Chemistry of the University of Kuopio, Finland, using a 3 min scan. The Department does not normally do analysis of furniture finishes or pigments and, as they had no relevant reference material, it was necessary to do some reference scans before analysing the finish on the tray. The reference samples, orange, yellow and clear shellac, mastic and two different dammars, were finely ground and pressed into 13 mm disks with KBr under 10 tons pressure for 10 min. The same was done to a minuscule particle of the original surface of the tray. The results confirmed that the finish was shellac. Binders that have been used for papier-mâché include starch, animal glue and gum arabic, possibly with added plasticisers. The paper tested negative for proteins (animal glue) in the ninhydrin test and negative for starch in iodine-potassium iodide solution. Thus I concluded that the likeliest binder was a polysaccharide, such as gum arabic. As gum arabic is a rather brittle adhesive on its own it is possible that some plasticiser was added before application. TreatmentAfter solubility tests the black paint layer was removed using scalpel, IMS and 10% IMS in Klucel G. During removal of the additional paint layer some scratching of the original layer had occurred, the revealed original layer had lost its natural lustre and was of a dull, brownish colour. To remedy these problems two surface polishes were tested: Microgloss and Acroglym. Both products are intended for polishing acrylic and plastic surfaces, are silicone-free and water-in-oil based emulsions. Microgloss seems to be the more abrasive of the two and, in the test, produced a shinier surface that made the tray look too glossy; Aeroglym produced a more appropriate level of shine. After inspection under a microscope, no residue showed on the test area so I proceeded with polishing the whole tray. The case of application of Aeroglym and its composition made me choose it for this job over other methods, e.g. T-Cut, or pumice powder and white spirit. Aeroglym is applied sparingly to the surface to be polished and allowed to dry. After drying it is buffed with a clean cotton cloth. It is easy to use, has a pleasant smell and produced impressive results. (You don't often get this combination in conservation!)Methods of papier-mâché restoration/ conservation are varied, but usually involve some attempt to use the original material, or even the original manufacturing technique. Various methods of using either paper pulp or layers of paper have successfully been used to repair structural loss in papier-mâché. The starting point for the tests for a new filler was an article by Marianne Webb. Using information from the article, I tried Paraloid B72 in xylene, in 25%, 30%, 35%, 40% concentrations, and microballoons, glass bubbles, colloidal silica and microfibres as fillers. I soon realised that while in lacquer restoration low concentrations of B72 are adequate, for structural filler concentrations above 40% are more appropriate. Of the bulking agents, colloidal silica was unsuitable, microballoons seemed too fine and soft for structural work and microfibres were too fluffy to have any strength. Glass bubbles seemed to be the most suitable bulking material, despite being somewhat coarse. However, the solubility of B72 in polar solvents was felt to be a serious disadvantage. To minimise the danger to the original surface from the future filler-material it was decided to pursue a further series of tests with B67, which is soluble in white spirit. While waiting for the Paraloid B67 test panels to dry, I decided to try out Primal WS-24 (an acrylic colloidal dispersion) as a binder for the filler. Primal was tried neat and in 50%, 60% and 75% concentrations in water. Primal is capable of holding a lot more filler than Paraloid and so fillers were mixed in a ratio of 1:4, instead of 1:2. As a result it was discovered that Primal provided better results more quickly than Paraloid B67. To achieve the hardness required from the filler in this case undiluted Primal was tried. Without water it is capable of holding slightly less than 1:4 ratio of the bulking materials, producing a hard material that can be sanded down satisfactorily, is touch dry in a day and achieves its final hardness in about a week when made into a layer of 15 to 20 mm thick. To give durability to the structural repair a key of laminated paper was used. Sugar paper slips were inserted into the paper substrate and 50% Primal in water was used as the adhesive. Carbon rod clamps were used to prevent dimensional expansion of the tray. Carbon rod clamps are ideal for small and/or delicate repairs where no additional weight should be placed on the object. In order to keep things as simple as possible, the same substance was used throughout the process, i.e. consolidating with Primal, filling with Primal-based filler and retouching with pigments in Primal. This way, should the material fall due to ageing, the whole repair would fall simultaneously. After the initial keys inserted into the tray had dried overnight, additional strips of paper were applied, one above and one underneath. These were not inserted into the original paper substrate as this could have caused thickening in the repaired areas. After leaving the keys to dry again overnight the edges were trimmed with scissors and scalpel so that they followed the outline of the existing rim. The filler, which had been mixed a couple of days before, was kept in a plastic bag to prevent it from drying and was applied on top of the key on the face side of the tray first. Modelling was done by hand. When the filler had dried sufficiently, it was levelled using a cabinet scraper and smoothed down with sandpaper. Then two coats of clear Primal were applied to smooth and harden the surface. The surface was then sanded down again with fine sandpaper to obtain a surface that was as smooth as the original surface. Two further coats of Primal (50%) were then applied and sanded down. Before retouching, the tray was polished again with Acroglym to re-clean the surface and to achieve a better colour match between the original surface and the inpainting. 50/50 Primal and water with hand-ground vegetable black pigment was chosen to colour in the repairs. The paint was applied in thin coats using a brush, smoothed down with sandpaper every two or three layers. This revealed some faults in the fills. To better disguise the joint between the fill and the original paper substrate Fine Surface Polyfilla coloured with vegetable black was used. This improved the appearance of the tray overall. The Polyfilla was smoothed down with sandpaper and blended into the existing repairs by an additional coat of black Primal. The application of Primal resulted in the repaired areas being shinier than the rest of the tray. Rubbing the repairs with fine wire wool, and then polishing the whole tray again (back and front) with Aeroglym solved the problem. The inpainting of decorative details on the filled areas (copied from the preserved areas) was also done using pigments and Mica-gold in Primal and a final protective surface coating of Briwax was applied. Timetable
ConclusionThe approach chosen for the conservation of the tray was one where modern alternatives were used in the conservation process instead of traditional materials. This approach was maintained constantly throughout the project.The main question arising from this treatment report is 'Was all that time spent testing for a filler worth it?'. As mentioned before, several methods of papier-mâché conservation were available for this project. I feel that in this case the experimentation was successful - even the fillers which were deemed unsuitable for this project gave me useful knowledge of the properties of different binders and fillers. Having never used a filler of this type before I have no knowledge of how it ages, which could cause problems. However, I believe this material is suitable since Primal is rated as a conservation standard material and both glass bubbles and microfibres are inert. This combination should thus create a material that remains stable through time and is easily identifiable as extraneous to the original object.
Bibliography
SuppliersEasy Sections Aeroglym and Microgloss Fillers Primal WS-24 Sugar paper Health and Safety GuidelinesAeroglym Paraloid B72 Paraloid B67 Primal WS-24 Glass bubbles, microfibres, microballoons and colloidal silica
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