Differential Development of Sickle Polish Due to Moisture Content of Herbaceous Plant Material

This experiment uses four experimental sickles containing flint and novaculite blades to harvest wet, growing grass and mature, dry rye in an effort to determine the differences in the development of sickle polish and other use wear traces caused by moisture content and other plant characteristics. During harvesting, samples of harvested material averaging about two handfuls were collected. These samples were massed, dried, and massed again to determine moisture content of the plants. The sickles were each used for approximately 13 hours. Each blade was then cast using high resolution dental epoxy for microscopic inspection. An edge survey was conducted along each blade starting at 100x magnification and increasing as needed to 200x. Microscopic examination of the sickle blades shows varying development of sickle wear stages. The flint blades used to harvest wet grass show higher levels of development of sickle gloss overall, with sickle gloss continuously coating the surface of the stone. The novaculite blades used to harvest wet grass show slightly lower levels of development of sickle gloss, with gloss discontinuously coating the surface of the stone. Both sickles used to harvest dry rye show barely developed sickle gloss, with gloss existing in isolated, discontinuous patches. The blades used to harvest wet grass show increased numbers of highly rounded microplating margins when compared to the rye sickles. Additionally, the difference in the abrasive nature of the plants generated different forms of striations. The tougher, more abrasive rye heavily striated the surface of the blades. The softer, fibrous grass produced finer striations on the surface of the blades. Microscopic inspection of the blades shows the process of rounding over the edge is likely a tandem process between edge abrasion and microplating, with the abrasion occurring first. While it is clear that moisture content affects the development of sickle gloss, other variables such as plant density, hardness, and abrasiveness were not controlled for and, therefore, potentially play an important role