Measuring the elastic properties of a green ceramic as it is being fired can be difficult and often requires sophisticated non-destructive testing (NDT) techniques. One effective method is called the the impulse excitation technique (IET).
IET is described in more detail in several standards (e.g., ASTM E1876 and C1259), but essentially involves measuring the natural frequencies of a test piece after it has been excited by a sharp mechanical impulse (light tap with a small hammer or impulse tool). The sample is supported and excited in such a way that a standing wave is produced in the sample. By supporting the sample at the nodes of the standing wave, external damping is minimized, and more accurate frequency and internal friction measurements can be obtained.