A slip for band-casting contains, on a weight basis, 100 parts alumina powder, 9 parts non-volatile organics and 35 parts toluene. The thickness of the dried film which adheres to the band on which it is cast is 0.6 of the cast thickness. What is the porosity of the tape
(i) after drying and
(ii) after the binder has been removed? On firing the shrinkage is a further 5% in thickness and the final total porosity is 5%. Estimate the shrinkage in the plane of the film.