Minecraft wiki entry for Armor, associated text: Armor can be repaired by placing two pieces of the same type (e.g., iron helmets) in a grindstone or in the crafting grid. The resulting item has 5% more durability left than the original items combined, if the total durability of both of the armor pieces is more than the total durability that a piece of armor would have fresh from a crafting table, but any enchantments are lost. Repairing armor with an anvil preserves and combines the enchantments, with a rising experience cost for subsequent repairs on the same item.