Rubidium hydroxide polyethylene glycol crown ether in the conservation of old master paintings*

The development of new, gentler methods for the conservation of Old Master paintings, with an emphasis on the removal or thinning of deteriorated varnish, is of high priority. In the course of the deterioration process, oxidative attacks lead to progressive formation of carboxylic acid groups, while many ester bondings are expected to be weakened. A stable RbOH polyethylene glycol complex was a promising tool to react with these moieties and to successfully break down the polymeric varnish layer. The remnants were easily wiped off mechanically. Control studies employing ⁸⁶RbOH and ¹⁴C polyacrylate showed the complete absence of residual cleansing components on the paint surface.     

青海汉代漆奁的脱水报告

采用聚乙二醇滴渗喷涂、真空冷冻干燥等浸饱水漆木器的脱水处理方法,对北方干燥地区槽朽漆木器进行了脱水保存。处理后器物尺寸稳定,色泽良好,保持了原貌。     

Preservation,storage and display of waterlogged wood and wrecks in an aquarium: “Project Aquarius”

A test aquarium containing water and waterlogged historical wooden material was observed during a three-year period at Vänernmuseum, Sweden, to test the feasibility of preserving and exhibiting archaeological wood or shipwrecks in a way accessible to the public. Experiments were also set up in a laboratory environment, to provide information on single factors that could influence the long-term preservation state of wood, and other processes that may occur in the water.     

New trials in the consolidation of waterlogged archaeological wood with different acetone-carried products

Some acetone-carried consolidants for waterlogged archaeological wood were tested in order to evaluate treatments able to save time and energy. In details, colophony (rosin), two esterified colophonies (Rosin 100^® and Rosin 459^®), a mixture of colophony with PEG 3400 and a vinyl acetate - vinyl versate copolymer (Vinavil 8020S^®) were tested. The treatments were carried out at temperatures of 20 and 35 °C on waterlogged maritime pine, elm, oak and beech. The materials came from the archaeological site of the ancient ships of Pisa (Tuscany, Italy) and were dated back to VII cent. BC – II cent. AD. To evaluate the processes, equilibrium moisture content and dimensional stability of treated wood samples at different relative humidity, and retention of impregnating products were measured; moreover macroscopic and microscopic examination were also run to respectively assess the shape and appearance of treated wood and the way of deposition of consolidants. The results highlighted that natural and modified colophony treatments gave the most satisfactory results both in the maintenance of shape and dimensions of samples and in the stabilization with respect to RH variations. Moreover, the equilibrium moisture contents of samples treated with R100 and R459 were much reduced in comparison to the other consolidants and to untreated archaeological wood. This fact was related to the high retention values of those products that occluded most of the porosity including the microporosity of cell walls. Therefore, in terms of higroscopicity treated wood was more similar to impregnating substances rather than to decayed wood. This fact was considered helpful in contrasting the moisture-related negative effects in cases of eventual faults in the climate control during e.g. exhibition and in protecting treated wood from the risks of new fungal attacks.     

对明代廖纪墓出土彩陶粉彩层的保护

通过对廖纪墓出土彩陶粉彩脱落原因和颜料成分分析,在多次实验的基础上,筛选出适宜的固色剂。经使用ＰＥＧ增加颜料致密性后再固色的保护方式,使固色后的粉彩层表面不泛光泽,平滑,触摸不掉色,保持了器物色泽的原貌,达到了保护粉彩层的理想效果。     

测量脆弱漆膜强度的夹具的研制及其在漆器修复中的应用

为了评价漆器修复过程中的回软程度,自行研制了一种能够表征面积微小、形态不规则的脆弱漆膜强度的夹具。该夹具与万能材料试验机配合使用,可对漆膜回软前后的强度进行定量测试。实验结果表明,陕西兴平墓葬出土的一明代漆棺残片,经聚乙二醇水溶液回软处理后,膜强度得到了明显提高,回软修复效果良好,该工作对亚浸水类型漆器文物的回软修复、保护具有科学指导意义。     

Investigations on pre-treatment prior to freeze-drying of archaeological pine wood with abnormal shrinkage anisotropy

The current research is aimed at determining the nature of changes in the dimensions and hygroscopicity of archaeological Scots pine (Pinus sylvestris L.) wood after treatment with polyethylene glycols and vacuum freeze-drying. The research was undertaken on mature sapwood with narrow annual rings and a small percentage of latewood. The experimental material used in a comparative assessment is characterised by a considerable degree of wood degradation, but low tangential and radial shrinkage and relatively high longitudinal shrinkage. The waterlogged samples were treated with aqueous solutions of PEG 300 with final concentrations: 8, 12, 16 and 20% (v/v), to which PEG 4000 with final concentration: 15, 20 and 25% (w/v) was added. After freeze-drying and seasoning of samples in the air at RH 30, 40, 50 and 65%, the water content of the samples and the degree of shrinkage of wood in three anatomical directions were determined. The dimensional stability of the samples was also determined on the basis of ASE values at RH 50%.     

To be and to continue being a cog: the conservation of the Bremen Cog of 1380

The conservation project for the Bremen Cog of 1380 took 38 years from salvage to presentation of the ship to the public in the Deutsches Schiffahrtsmuseum in 2000. The ship was salvaged from the River Weser in about 2000 pieces, and stored in water tanks. A new museum was built, and the Cog reassembled from the waterlogged timbers. The ship was reconstructed with most of the weight being taken by the ceiling of the hall via a steel-rod hanging system. Then a conservation tank was built around the hull, and a novel two-step PEG-treatment applied, especially developed for the Cog. In two consecutive baths PEG 200 and PEG 3000 stabilized lesser degraded and heavily degraded wood against shrinkage, splitting, and warping. After cleaning, the wood looks dark brown, dry, and natural. The extraordinary project is regarded a success.     

木材在PEG法处理过程中收缩原因的研究

论述了PEG法处理木质文物过程中造成木材收缩的原因。讨论了木材含水率、浸泡温度、PEG分子量以及其浓度变化梯度等因素与木材收缩的关系。还介绍了弥补PEG法不足的一些简单方法。