text: In the past, to construct armor leather was hardened by soaking it in boiling water.\n\nSee:\nhttp://www.daviddfriedman.com/Medieval/Articles/Perfect_Armor_Improved.htm\n\nhttp://www.dagorhir.com/HowTo/cbgryml.htm\n\nThe M1 Steel Combat Helmet, a piece of body armor could also be used (and was) used for boiling water.   See:http://www.globalsecurity.org/military/systems/ground/m1-steel-pot.htm