A structured product, comprising: at least two layers comprising a first layer and a second layer; wherein: the first layer comprises at least one material having a temperature-dependent (e.g., a positive temperature-dependent or a negative temperature-dependent) wavelength-integrated emissivity (ε); the second layer comprises at least one reflective material that is reflective to light in an 8-14 μm wavelength range; and the structured product has a positive temperature-dependent wavelength-integrated emissivity. The structured product is useful in a method for thermal image sensitizing, the method comprising imaging, in an infrared spectrum, the structured product.