How hard is my material's surface?

Getting a fast, standardized number for how much a material's surface resists permanent indentation.

References

• Smith, R.L., Sandland, G.E. "An Accurate Method of Determining the Hardness of Metals, with Particular Reference to Those of a High Degree of Hardness." Proceedings of the Institution of Mechanical Engineers 1, no. 1 (1922): 623–641.