A non‐destructive technique for gauging the chemical composition of the surface layers of materials such as pottery and glass. A sample is bombarded by a collimated beam of electrons from a weak radioactive beta source. The sample is arranged at 45 degrees to the beam with the backscatter particles counted using a Geiger counter. The whole system is portable and being nondestructive can be used on museum specimens in the field. The drawback is that the system is unable to identify specific elements responsible for the backscattering; it can only measure the presence of known elements of high atomic number within a matrix of low atomic number (for example, lead in glass).