Marking petroglyphs with chalk is a common practice to enhance them for documentation and reproduction. Although this procedure has started to be less frequently used, there is no knowledge about the interaction between the rock engravings nor about the effectiveness achieved by the common cleaning procedures of such markers considering the chalk extraction and the induced damage to the rock.This study evaluates the interaction between two chalks of different composition (calcite and gypsum) and a granite on which the majority of NW Iberian Peninsula-petroglyphs are carved. Granitic samples marked with these chalks were subjected to artificial rain events and high temperatures (700 °C) related to fires. After each aging test, chemical and physical modifications on the rock were analysed by means of stereomicroscopy, x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and colour spectrophotometry. Moreover, the evaluation of the effectiveness and harmfulness of several mechanical and chemical cleaning procedures commonly used in the field of cultural heritage conservation was carried out.Both chalks remained at different extent on the surface after the artificial rain events. Water would promote a different penetration-depth of the chalks into the stone, depending on their solubility. High temperatures led to mineral phase transformations of the chalks influencing the interaction with the rock.Regarding cleaning effectiveness, despite a few chalk remains were found in all the cleanings, chemical methods showed higher effectiveness than mechanical procedures even though some of them leave chemical contamination. Benzalkonium chloride can be considered as the cleaner with the best results to extract both types of chalk on granite.

中文翻译：

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用方解石和石膏基粉笔标记刻在岩石上的文字：在不同的模拟条件下与花岗岩的相互作用以及清洁方法的有效性和有害性

用粉笔标记刻在岩石上的文字是一种常见的做法，目的是增强它们的记录和复制能力。尽管这种方法开始不那么频繁地使用，但对于岩石雕刻之间的相互作用以及关于这种标记物的常见清洁方法所考虑到的白垩提取和对岩石造成的损害，其有效性的了解都还不为人所知。这项研究评估了两种成分不同的白垩（方解石和石膏）与花岗岩之间的相互作用，该花岗岩上雕刻了大多数西非伊比利亚半岛的岩画。用这些粉笔标记的花岗岩样品经受了人工降雨和高温（700 °C）与大火有关。每次老化测试后，通过立体显微镜，X射线衍射，傅立叶变换红外光谱，扫描电子显微镜和彩色分光光度法对岩石的化学和物理改性进行分析。此外，还对文化遗产保护领域中常用的几种机械和化学清洁程序的有效性和有害性进行了评估。在人工降雨事件之后，两种粉笔都以不同程度保留在表面上。根据其溶解度，水会促进白垩渗透到石头中的深度不同。高温导致白垩的矿物相变影响与岩石的相互作用。关于清洁效果，尽管在所有清洁过程中都发现了一些白垩残留物，但化学方法比机械方法显示出更高的有效性，尽管其中有些方法留下了化学污染。苯扎氯铵被认为是在花岗岩上提取两种粉笔效果最好的清洁剂。