→ 3. Metal Hardness

The four pinpoints are from the hardness tests. These are the points of resistance from the diamond-pointed pins pressing into the surface of the metal. The pressure of indentation is an indication of the alloy’s ability to keep a cutting edge. The harder the alloy, the greater the penetration and effectiveness of the arrowhead in battle. The alloying of 1% tin changed the micro-structure and grain size thereby doubling the hardness of the alloy. The harder the metal, the greater the resistance of the diamond points to penetration.