1 Department for Conservation of Antiquities and Works of Art, Technological Educational Institute of Athens, Greece.
2 Athens University of Applied Sciences, Athens, Greece.
Appl Spectrosc. 2018 Oct;72(10):1511-1527. doi: 10.1177/0003702818778319. Epub 2018 Aug 30.
The question for discriminating iron gall inks is addressed by correlating their infrared (IR) spectra in liquid and dried states with the materials used in their formulations and considering their possible interactions. A series of laboratory inks were prepared according to historic recipes, mainly found in 19th-century documents, and were accordingly studied using Fourier transform infrared (FT-IR) spectroscopy. All ink formulations were based on Aleppo galls, ferrous sulfate, and gum arabic at variable proportions, with various added components, such as alum, vinegar, glycerol, sugar, silver nitrate, cloves, and white wine. Ingredients of the corresponding inks were recognized by means of their IR fingerprints in both their liquid and dried states, respectively. Although a few inks of distinct formulations showed discernible differences in their spectra, the majority showed quite similar absorptions. Principal component analysis and discriminant analysis were employed to successfully discriminate inks, based on their IR peaks. Spectra recorded in the liquid state, despite their broad absorption features, led to satisfactory discrimination of certain types of inks as most of their ingredients are reflected in their IR peaks. Spectra from dried inks contained similar information, which equally worked in a sufficient discriminatory way. Key IR peaks in the recorded spectra of inks made with the addition of special ingredients, such as vinegar, wine, alum, glycerol, and sugar, as well as those prepared with specific tannin-enhancing procedures, such as gall boiling, were located and used in the discrimination basis.
用于鉴别铁胆墨水的问题是通过将其液态和干燥状态下的红外（IR）光谱与其配方中使用的材料相关联，并考虑它们可能的相互作用来解决的。根据主要在 19 世纪文献中发现的历史配方，我们制备了一系列实验室墨水，并使用傅里叶变换红外（FT-IR）光谱对其进行了相应的研究。所有的墨水配方均以阿勒颇（Aleppo）胆为基础，硫酸亚铁和阿拉伯树胶的比例可变，并添加了各种成分，如明矾、醋、甘油、糖、硝酸银、丁香和白葡萄酒。通过分别在其液态和干燥状态下的 IR 指纹识别相应的墨水成分。尽管少数具有不同配方的墨水在其光谱上表现出明显的差异，但大多数显示出相当相似的吸收。基于它们的 IR 峰，我们采用主成分分析和判别分析成功地对墨水进行了分类。尽管液态下的光谱具有广泛的吸收特征，但它们仍然可以对某些类型的墨水进行令人满意的区分，因为它们的大多数成分都反映在其 IR 峰中。干燥墨水中的光谱包含类似的信息，同样可以以足够的区分方式工作。记录的加有特殊成分（如醋、酒、明矾、甘油和糖）的墨水以及采用特定单宁增强程序（如胆煮沸）制备的墨水的记录光谱中的关键 IR 峰被定位并用于鉴别基础。
