In 2006 the commanding general of the US Marines in Iraq banned his men from wearing the most popular sports shirts in America, because of what the burns surgeons were finding. It was 50 degrees in Anbar province. The issued cotton T-shirt was soaked through in minutes, so Marines had been buying their own. Tight, light, sweat-wicking tops in polyester, the kind every gym in the country is full of. They were cooler and they dried fast. Nearly everybody had them on under the body armour. Then the roadside bombs started. A bomb under a vehicle produces a flash of fire lasting a second or two. Cotton scorches in that time. Polyester melts. The Navy doctors at the field hospitals described the result. The shirt turned to liquid and set again on the man's chest and back. A burn that should have been survivable became a far worse one, because there was now a layer of plastic fused across it that had to be cut away. In April 2006 the order went out from Camp Fallujah. No synthetic athletic clothing outside the wire. It named the brands. The Marines then went looking for something that wicked sweat, dried fast, did not stink after a week and would not melt. What they found had been grazing in New Zealand the whole time. Fine merino wool is now standard issue next to the skin for troops who expect fire. That is twice in 25 years, in two different services, that plastic clothing has been tested on young men by an explosion. Both times the answer came off a sheep.