What is Infrared Radiation?

The IR signature can still be detected because the cool air does not inhibit the radiation. Assuming the second plastic cube was not opaque, then the IR would pass through mostly undisturbed.

In order to completely erase one's IR footprint one would have to have a "cube" that is conductive, as conductive materials impede radiation: something like copper foil, aluminum foil, mylar etc. However, this shielding would only prevent an IR camera from being able to discriminate objects that are obscured by the foil; it would not hide the fact that the foil is at a temperature warmer than normal(if in fact it is). A second layer of foil (spaced apart from the first) would need to be employed.

Eventually, the heat from the first cube would reach the second via convection and so an IR camera could potentially detect that the outer shield is at above average temperature. Circulating cool air between shields would prevent the outside shield from ever becoming warm enough to be detected.

The first shield will not re-radiate IR (such is supposed to be the case with mylar) but will still convect heat, which may still result in an IR footprint, depending on the setup.

So, one shield of foil is fine to conceal visual information but it will not prevent the shield itself from appearing warmer than it should, which for some people may be a concern. A second shield with cooling air running between the two shields is necessary to both conceal discriminating features and the actual temperature of the room.

Since the heat never convects (because it is cooled), neither convection nor (much)radiation makes it to the second sheet of mylar.

For those wanting to protect themselves from rogue IR camera fiends, the aforementioned setup is unrealistic but ideal.

How does infrared technology work? thank you.

@ Amphibious54- People might like to know how to prevent detection by IR sensing cameras in certain military situations as well. Insurgents in Iraq and Afghanistan have used some of the tactics I will list below to prevent IR detection.

Water is a good insulator; dispersing heat very quickly. In some environments, staying in or near water when IR cameras are suspected can help to avoid detection. In arid environments, lying prone and covering yourself with a wool blanket can mask your heat signature from planes or drones flying overhead since they will trap the heat given off by your body.

Light color clothes also reflect incoming IR so it can keep the subject cooler, requiring less to mask their IR signature. Mylar can also prevent a camera from picking up an IR signature, but beware the reflective nature of Mylar can give away your position just as easily.

@ Anon13625- Infrared radiation can be reflected by many materials. The earth's atmosphere is a good reflector of IR, and is what regulates the earth's surface temperature. This is why an overcast day is cooler than a sunny cay and an overcast night is warmer than a cloudless night. The clouds act as insulation, either preventing IR from penetrating to the surface or leaving into space.

One could apply this concept to other situations as well. Retaining IR can be the difference between survival and death in some situations. A person in a survival situation could use certain materials like Mylar and plastic sheets to reflect IR waves for warmth.

Creating pockets of air can also help to create a barrier to IR waves. For example, a clear plastic cube filled with hot air placed in a dark room would show up on an IR camera. If you were to enclose that plastic cube inside of another plastic cube with cool air, the camera probably would not pick up the IR signature.

what absorbs ir and what are the reflectors of it? thanx