Question:We cannot see infra red radiation so what can we tell about a surface by looking at it?
If a surface appears shiny or mirror like, then they are reflecting visible light effectively. Usually, these surface will be good at reflecting infrared too. Remember that infra red is right next to red on the electromagnetic spectrum so it is reasonable to assume as just a rough guide that what a surface does to visible light it will also be doing to some degree to infrared radiation. So shiny surfaces are usually also shiny to infrared radiation.