Abstract
It was very difficult to directly measure the roughness of heavy castings up to this time. Without preparing for the test-piece specially, the ronghness of heavy castings can be measured by means of this method. 1) After studying the plastic substances made from Gypsum and Urea-Resine, it was cleared its special qualities. 2) Studying the method of reproducing the surface of castings, it was successfully discovered to make the strong plastic test piece used for the reproduction.
