Application methods, techniques and kinematics

As discussed above, two different methods of applying the flint strike-a-light to the sulphuric iron contact material were employed in this study: the percussion method and the friction method. The utilized edge on every experimental piece was the dorsal edge of the striking platform, save for one where a naturally rounded edge was worked. The reasoning behind selecting the proximal dorsal edge of the striking platform as the primary working edge for the experiments lies primarily in the fact that this edge on average tends to be thicker than the lateral and ventral flake edges and has a higher relative platform-to-dorsal surface angle, which creates a sturdier working edge more resistant to edge failure, an important feature when being applied to a hard contact material like sulphuric iron with the amount of force necessary to create sparks.

To account for variations in usewear traces caused by gesture differences, some experimental pieces were held so the working edge was brought across the contact-surface transversely to the edge, while others were applied longitudinal to the edge. This creates four groups of experiments based on the method applied and the positioning of the tool edge: friction/longitudinal, friction/transverse, percussion/longitudinal, and percussion/transverse. Experiment 2006 was placed into a fifth category – the percussion/natural group – due to the very different character of the naturally rounded surface employed by that strike-a-light.

Prior to experimentation, ‘practice runs’ were conducted using the abovementioned methods to determine what hand grip and body position was the most comfortable and effective in generating sparks, while still being easily visible during video recording. Every attempt was made to be as consistent as possible within and between each experiment group, though given that not all the strike-a-lights were of the same size or shape, some minor differences were inevitable. All experiments were conducted while kneeling on the right knee, left elbow resting on the left knee, the strike-a-light held in the right hand and actively applied to the sulphuric iron nodule held passively in the left hand.

For the friction/longitudinal method, the sulphuric iron nodule was firmly gripped in the left hand with the contact-surface positioned slightly tilted off-vertical (ca. 10-20 degrees) away from the body (see Appendix VII for video of the various techniques applied for each experiment). The strike-a-light was gripped firmly between the thumb and forefinger with the working edge of the tool in a vertical position. For a single stroke, the working edge was placed near the top of the contact-surface applying moderately firm pressure. Using a linear vertical wrist and forearm movement, the tool was brought sharply downward for the length of the contact surface, with the stroke generally progressing to around 10-cm beyond the edge of the contact surface.

For the friction/transverse method, the sulphuric iron nodule was firmly gripped in the left hand with the contact-surface positioned slightly tilted off-vertical (ca. 10-20 degrees) away from the body. The strike-a-light was gripped firmly between the thumb and forefinger with the thumb on top, the tool itself held at an approximately 45 degree angle to the length of the forearm with the working edge in a horizontal position. For a single stroke, the working edge was placed near the top of the contact-surface applying moderately firm pressure directed into the surface. Using a slight twisting wrist-action and straight vertical forearm movement, the tool was brought sharply downward for the length of the contact surface, directing the stroke across the top of the surface of the striking platform, with the stroke generally progressing to around 10-cm beyond the edge of the contact surface.

For the percussion/longitudinal method, the sulphuric iron nodule was firmly gripped in the left hand with the contact-surface positioned slightly tilted off-vertical (ca. 10-20 degrees) away from the body. The strike-a-light was gripped firmly between the thumb and forefinger with the working edge of the tool in a vertical position. For a single stroke, the working edge was positioned approximately 10-cm above and away from the contact surface. Using a linear vertical wrist-action and forearm movement, the tool was brought sharply

downward striking near the center of the contact surface, with the stroke generally progressing to around 10-cm beyond the edge of the contact surface.

For the percussion/transverse method, the sulphuric iron nodule was firmly gripped in the left hand with the contact-surface positioned slightly tilted off-vertical (ca. 10-20 degrees) away from the body. The strike-a-light was gripped firmly between the thumb and forefinger with the thumb on top, the tool itself held perpendicular to the length of the forearm at an approximately 45 degree down-angle from horizontal. The tool was brought sharply downward with the forearm and slight wrist-action at an approximately 45 degree angle directing the blow more ‘into’ the center of the contact-surface (verses more across the surface as in the other experiments), with the stroke generally progressing down and away from the contact-surface after the impact and terminating around 10–20-cm beyond the edge of the contact surface. This grip and positioning direct the blow across the dorsal surface of the strike-a-light as opposed to across the top of the striking platform. The reason for this was that during the ‘practice experiments’, it was determined that striking across the top of the platform resulted in a higher incidence of fragments being detached from the strike-a-light (i.e. edge-removals and edge-failure) and projected towards the operator’s face, making the method appear too unsafe to be a practical.

The percussion/natural group (Experiment 2006) - a tool type unique to the data set - required a striking technique that employed a grip similar to that used for the percussion/longitudinal group, but the blow trajectory corresponded more closely to that of the percussion/transverse group.