Summary | Introduction | Method of Analysis | Sample for analysis | Results of the functional analysis | Analysis of the functional results | Statistical analysis of use-wear data | Ethnographic data | Users | Change in edge angles | Relations between the four phases | Discussion

6.9 Change in edge angles

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.

Table 16. Edge angles before and after tool use and changes as a result of use on different materials
material worked angle before use angle after use difference rate of change in angle (°s-1)
bone 38.6° 39.6° 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