Shore durometer B, C, D, DO, E, M, O, OO, OOO, OOO-S, and R. Each scale results in a value between 0 and 100, with higher values indicating a harder material. Durometer, like many other hardness tests, measures the depth of an indentation in the material created by a given force on a standardized presser foot. This depth is dependent on the hardness of the material, its viscoelastic properties, the shape of the presser foot, and the duration of the test. ASTM D2240 durometers allows for a measurement of the initial hardness, or the indentation hardness after a given period of time.
North Shore (Lake Superior) efforts, many of the forests along the North Shore are now protected from deforestation, but there is still a strong paper industry that relies on pulpwood. In 1855 when a lock system first allowed steamboats onto the lake, eastern tourists began to travel onto Lake Superior for recreational purposes. They would then canoe or be ferried from Duluth up the North Shore and would stay in hunting and fishing camps. In the 1920s, the North Shore highway was built, which helped make the North Shore accessible by land. At the same time commercial fishermen began to go out of business