Fig 1.
A: overview; 1: Load(20N); 2: sample holder; 3: worked material (ivory). B: close-up; 3: worked material (ivory); 4: chert bit; 5: wear track.
Fig 2.
(a) Conventional Steel ball used in pin-on-disk type of Tribology Experiment, (b) Customized Sample holder setup (on left) conventional sample holder (on right), (c) Customized sample holder, Customized sample holder with Flint sample & the stone sample on the sample holder rod (from left to right).
Table 1.
Input parameter used for the tribological experiment with the archaeological samples.
Fig 3.
Step by step procedure for calibration of the load sensor in Nanovea T50.
Fig 4.
Material reaction during the nanoindentation process.
A: Schematic drawing showing the surface displacement during indentation; B: A typical indentation P-h curve where hc is the maximum true contact displacement during loading, Pmax refers to the maximum load applied during the indentation cycle, S is the initial unloading stiffness, hf is the final plastic depth from the P-h curves, hs is the residual depth after complete unloading and hmax is the indent.
Table 2.
Raw materials average hardness and Er values.
These values are calculated by taking all the measurements into account for each sample. Materials are listed in increasing order of hardness, from the softest (Spruce) to the hardest (Flint).
Fig 5.
Visual representation of the surface parameters.
(from Martisius et al., 2018 [49] (doi: https://doi.org/10.1371/journal.pone.0206078.g004).
Fig 6.
100X pictures of the polished areas taken with the Sensofar.
A) Surface modifications formed by rubbing the stone bit on Spruce wood. B) Surface modifications formed by rubbing the stone bit on Beech wood. C) Surface modifications formed by rubbing the stone bit on bone. D) Surface modifications formed by rubbing the stone bit on antler. E) Surface modifications formed by rubbing the stone bit on ivory.
Fig 7.
Polish development after 5 hours of use.
The samples are organized by hardness order, from the softer on top of table to the harder on the bottom.
Fig 8.
Boxplots showing the evolution of flint roughness parameters Sa, Sal, Spc, and Smr1 after 1 hour, 3 hours and 5 hours of use on worked materials of various hardnesses.
The diagrams in the first column represent the expected microtopography for a high value (on the top part of the cell) or low value (on the bottom part of the cell) for each parameter (extract from Martisius et al., 2018 [49]).
Table 3.
Paired t-test results with the Bonferroni correction and their significance for the parameter Sa after five hours of use.
Table 4.
Result of the Kendall’s tau correlation test for the four texture parameters.
Fig 9.
X-ray microanalysis of the spruce wood powder.
The red square represents the scanned area. This area is mainly composed of Silicon, suggesting that the fragment (white on the picture) is a flint fragment.