IR cameras see the differences in temperature. If you are wearing a skin piece, I could see how IR cameras will show the skin material, not because scalp under it is warmer, but because the skin material blocks IR radiation so the camera will actually see it as cooler.

If you have a lace unit, IR cameras should not see anything. I have a FLIR thermal camera and this is what I see. Notice how my glasses show up very dark because the lenses are blocking IR radiation.

---