This research presents a set of methods for obtaining measurable data on yarns in historical textiles, addressing a gap in conservation and conservation science. A systematic analysis was conducted on 26 specimens, primarily from historical paintings of known provenance, all including a selvedge. Techniques for measuring crimp, twist, yarn width and yarn thickness were developed. Methods for the measurement of thread count, fabric thickness, weight, and pH are also discussed. By quantifying these characteristics, this study enhances our understanding of traditional textile production. Numerical data enable direct comparisons between different fabric structures and allow correlations with the tensile properties of historical textiles. Correlations have been established between the measured characteristics of the interlaced yarns and the warp and weft directions, which appear to be uncontroversial within this group of samples. This improves the ability to distinguish warp and weft in a textile when a selvedge is not available. The set of methods is largely non-destructive, as only a few yarns need to be extracted to measure their crimp and thickness. The data needed for textile engineering research are made available for historical woven structures, providing new opportunities for their analysis and for predictive digital simulation. The next steps in this ongoing research are to explore correlations between the measured characteristics and the tensile response of the analysed textiles, and to extend the study to a wider range of historical fabrics to obtain more broadly representative data.

Twist and crimp values are of paramount importance to the textile industry in understanding the properties and performance of a textile, and their quantification has been a subject of study since the early 20th century. Twist and crimp are the result of how the fibers have been modified from the original bundle to shape the textile, so the industrial methods used to measure them are based on mechanically reversing such deformations. The same information is needed to study the mechanics of historical fabrics such as canvas paintings supports and historical textiles, but they are more difficult to obtain because these are often brittle and impregnated with foreign materials, less homogeneous and very limited in availability for sampling. Therefore, such fundamental parameters are usually unavailable for conservation studies.

This paper examines the protocols used in the textile industry and proposes new methods, developed from previous research, for the reliable measurement of twist and crimp in historical textiles. The twist measurement method is non-destructive as it is based on observing the textile and the fibers on the surface of the yarn. Crimp is the undulation of the interlaced yarns and its measurement is an invasive examination of the internal structure of the textile, as it requires the observation of individual yarns. Both methods, applied here to a group of historical textiles, provide data in accordance with the current parameters of the textile industry, and their use is relatively simple and inexpensive.

The mechanical aspects of canvas painting conservation and the study of the effects of conservation treatments benefit greatly from quantifying the mechanical characteristics of the materials. However, this is seldom possible as only few labs have the necessary equipment. This paper presents the development of a biaxial tester to be used for samples of canvas paintings which exhibit orthotropic behavior under biaxial loads. The machine was built as the first step of ongoing Ph.D. research on the mechanics of canvas paintings. An effort was made to create a system that is easy to assemble, with parts that are easy to source and with an overall cost well below the commercial units available. The control software includes the function of automated pre-tensioning to improve the accuracy of the measurement. Our broader purpose here is to make an easy-to-replicate machine available to help conservators and conservation scientists perform tensile tests to make informed choices in materials science.