An assessment of the ranges of edge-angle difference indicates that the average increase in angle size after use for all tools was 3.6° (Table 16). The increase varied according to material worked on.
| material worked | angle before use | angle after use | difference | rate of change in angle (°s-1) |
|---|---|---|---|---|
| bone | 38.6° | 39.6° | 1° | 0.0118 |
| tree fern | 40.2° | 44° | 3.8° | 0.0084 |
| grass | 34.9° | 37.8° | 2.9° | 0.0051 |
| wood | 49.9° | 52.5° | 2.6° | 0.0042 |
| bamboo | 39.3° | 43.8° | 4.3° | 0.0060 |
| rattan | 33.1° | 37.5° | 4.4° | 0.0051 |
| vine | 24.8° | 30° | 5.2° | 0.0045 |
| butchering | 24.5° | 30° | 5.5° | 0.0045 |
Table 16 suggests a wide difference in edge-angle alteration related to raw material. In fact, rather than the raw material itself altering the edge angle, it is the sharpness of the original angles that vary. This table reflects the degree of selection of tools according to the material to be worked on, with softer, pliable materials worked with a sharp, low-angled edge, which wore down more quickly. The harder materials were worked with wider broader-edged pieces which wore down less quickly and were used for a longer time (Table 15).
Edge-angle differences were found to have no significant effect on the length of time a tool was used. The sixteen tools which had been used for the shortest time had an average edge-angle increase of 3.6° while the sixteen tools which had been used for the longest time had a smaller average increase of 3.2°. This may be due to differences in the material being worked by the tools and to the sharpness of the original edge angles. Selection of tools for use on different materials was strongly based on the tool thickness (P<0.001) and edge thickness (P<0.01).
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Last updated: Wed Oct 8 2003