As the nanoparticles that are used to block the incoming X-ray photons are selected to have a high X-ray attenuation (with a high atomic number ‘Z’ in the periodic table of elements), our material is particularly well suited to the inspection of challenging industrial products. Where thick objects (such as steel) need to be inspected at higher X-ray energies to ensure that the X-rays can penetrate the object under test, our material offers a new alternative for non-destructive test (NDT).