US Patent 9377424 Methods of detecting latent stains on a surface

Methods for identifying chemical contrasts on a common surface are generally provided. The presence of a stain on a surface can be detected by applying a testing vapor, such as water, onto the surface and monitoring the surface with an infrared camera that detects wavelengths of about 700 nm to about 1 mm and/or a microbolometer that detects wavelengths of about 7.5 μm to about 14 μm. The surface may be at room temperature or preheated during the detection method.