Six repetitions of the Guettler diagram. To facilitate visual comparison across plots, the y-axis has been cropped to accommodate the same force values in each plot. The top-left plot is identical to Figure 6 and serves as a reference. The remaining plots depict Guettler diagrams acquired by systematically varying bowing parameters in either ascending (top row) or descending (bottom row) order during the measurement sessions. The left and centre columns show results obtained on consecutive days without removing the string from the apparatus. The rightmost column displays Guettler diagrams measured after a one-month interval, with the string having been dismounted and remounted in the meantime.