This issue of the Journal of the American Institute for Conservation comes in the middle of the COVID-19/coronavirus pandemic, which is arguably one of the most difficult global emergencies faced by the world in recent times. The profound impact of the pandemic across the social, economic, political, and psychological spheres is quite concerning. We are experiencing changes such as postponement of the 2020 AIC Annual Meeting, while organizing a virtual meeting this year in the current uncertain context due to the pandemic. Furthermore, this journal’s publisher Taylor & Francis has suspended print editions of journals from April 10 until further notice. Online access to journal content is not affected, and print issues of the journal will be sent to AIC members once they resume printing. Under these circumstances we present the second issue of 2020, which contains four articles that provide interesting solutions to important conservation problems evidencing once more the importance of multidisciplinary work in the cultural heritage field. The papers show that collaboration among different disciplines remains essential; a consistent use of analytical techniques applied to the study of materials and methods continue to increase our access to deeper information about key cultural heritage objects. The objects under question are all paper based and include lithographic and photographic prints as well as Leonardo da Vinci’s Codex Leicester. To enhance this paper-themed issue, we feature book reviews on Holbin Ellis’s The Care of Prints and Drawings, 2nd ed., and Banik and Brückle’s Paper and Water: A guide for conservators, 2nd ed. “Computational Watermark Enhancement in Leonardo’s Codex Leicester” by Sethares et al. comes in a very important historic moment as celebrations of Leonardo da Vinci’s great legacy continue to take place around the world as part of the 500 anniversary of the master’s death in 2019. The authors present a computational enhancement procedure to minimize surface writing and enhance the watermarks and chain lines/wires detectable in the papers found in Leonardo’s notebooks. The use of imaging techniques together with mathematical optimization procedures were able to enhance the watermarks and other features to allow deeper study of these important papers. The tools and methods developed as part of this research will be available to researchers dealing with similar signal obscuring problems as an open source package. Taylor et al. argue that physico-chemical properties of stone papers used for lithographic printing deserve more research attention as the results can provide meaningful insight on the materials, manufacturing processes, and printing methods used in the nineteenth century. The authors present a technical study conducted on Théodore Géricault’s Lion Devouring a Horse lithographic printing matrix, dated to 1820-1821. They describe multidisciplinary work using both imaging and analytical techniques, to learn more about the support, the information layer, and the coating found on Gericault’s work. The authors prepared a series of mockups to better understand the properties of stone paper and correlate the findings to the results obtained from their stone paper matrix analysis. In addition, the preservation of stone papers was investigated. An interesting finding was that the presence of casein used as a coating for printing may also be associated with losses in the image due to the formation of a fragile film. The last two articles deal with issues related to photographic prints. O’Connor et al. focus on a selection of works by Edward Steichen, an artist that broke the boundaries between painting and photography. This interdisciplinary research project involved collaboration between curators, conservators, and scientists. The scientific part of the study involved the use of X-ray fluorescence (XRF) spectrometry and Fourier transform infrared (FTIR) spectroscopy to determine the composition of the print and surface coatings, respectively. The results allowed for comparison of different processes associated with an evolution in the artist’s technique. In sum, the researchers that participated in the study were able to make significant progress on the characterization of materials and methods of Edward Steichen, an artist that continuously experimented in his works. The second article on photographic prints by McClelland et al. focuses on the analysis of the surface of photographs, specifically on coatings. This work involved the creation of a specular reflection FTIR spectral library of photographic materials used in the 19 century. Instead of focusing on individual band assignment, the authors propose to use the full spectrum measured as a chemical signature to classify a coating within a particular group. The authors found that although some coatings were used to protect the photographic image, they frequently deteriorate with aging. This situation is analogous to what Taylor et al. report in their article for coatings found in stone papers used for lithographic printing. By following a non-destructive approach, the authors were able to enhance the existing knowledge on issues pertaining to cultural and historical aspects of historic photographs as well as their attribution and preservation issues.

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社论

本期《美国保护学院学报》正处于COVID-19 /冠状病毒大流行的中期，这可以说是当今世界面临的最困难的全球紧急情况之一。大流行在社会，经济，政治和心理领域的深远影响令人担忧。我们正在经历诸如2020年AIC年度会议推迟之类的变化，同时由于大流行而在当前不确定的背景下今年组织了一次虚拟会议。此外，该期刊的发行人Taylor＆Francis已于4月10日暂停期刊的印刷版，直至另行通知。在线访问期刊内容不会受到影响，并且期刊的印刷问题将在AIC成员恢复打印后发送给他们。在这种情况下，我们提出了《 2020年第二期》，其中有四篇文章为重要的保护问题提供了有趣的解决方案，再次证明了在文化遗产领域开展多学科工作的重要性。这些文件表明，不同学科之间的合作仍然至关重要。始终如一地使用用于材料和方法研究的分析技术，继续增加了我们获取有关关键文化遗产物体的更深入信息的机会。所涉物品全部为纸质物品，包括石版印刷和照相印刷品以及达芬奇的莱斯特法典。为了增强这个以纸为主题的问题，我们在Holbin Ellis的《版画和素描的护理》（第二版）以及Banik和Brückle的《纸与水：储户指南》第二版中进行书评。Sethares等人的“ Leonardo's Codex Leicester的计算水印增强”。这是一个非常重要的历史性时刻，作为2019年大师去世500周年纪念活动的一部分，在世界各地继续庆祝莱昂纳多·达·芬奇的伟大遗产。作者提出了一种计算增强程序，以最小化表面书写并增强水印以及莱昂纳多笔记本中发现的链条/电线。成像技术与数学优化程序的结合使用可以增强水印和其他功能，从而可以更深入地研究这些重要论文。作为本研究的一部分开发的工具和方法将作为开源软件包供处理类似信号模糊问题的研究人员使用。泰勒等。认为用于平版印刷的石头纸的理化性质值得更多的研究关注，因为其结果可以提供有关19世纪使用的材料，制造工艺和印刷方法的有意义的见解。作者介绍了ThéodoreGéricault的《狮子吞噬马》石版印刷矩阵的技术研究，日期为1820年至1821年。他们使用成像和分析技术描述了多学科的工作，以更多地了解Gericault工作中的支撑，信息层和涂层。作者准备了一系列样机，以更好地了解石纸的特性，并将这些发现与从他们的石纸基质分析中获得的结果相关联。此外，还研究了石材的保存。一个有趣的发现是，由于形成了脆性膜，酪蛋白用作印刷涂料的存在也可能与图像损失有关。最后两篇文章讨论与摄影作品有关的问题。O'Connor等。重点介绍了打破绘画与摄影界线的艺术家爱德华·史提琴（Edward Steichen）的精选作品。这个跨学科的研究项目涉及策展人，保护人和科学家之间的合作。该研究的科学部分涉及使用X射线荧光（XRF）光谱和傅里叶变换红外（FTIR）光谱来分别确定印刷品和表面涂层的组成。结果允许比较与艺术家技术发展相关的不同过程。总共，参与这项研究的研究人员在爱德华·史提琴（Edward Steichen）的材料和方法的表征方面取得了重大进展，爱德华·史提琴（Edward Steichen）不断地对其作品进行实验。McClelland等人的第二篇有关摄影作品的文章。重点分析照片的表面，特别是涂层。这项工作涉及创建19世纪使用的照相材料的镜面反射FTIR光谱库。作者建议不要将注意力集中在单个波段上，而是将测量的整个光谱用作化学特征，以对特定组中的涂层进行分类。作者发现，尽管使用了一些涂料来保护摄影图像，但它们经常随着老化而变质。这种情况类似于Taylor等人的情况。在他们的文章中报道了用于平版印刷的石头纸中发现的涂料。通过采用非破坏性方法，作者能够增强有关历史照片的文化和历史方面及其归因和保存问题的现有知识。