1. A test procedure to measure a test specimen comprising the steps of applying a first casting compound to a surface of a test specimen; maintaining the casting compound on said surface for a time sufficient for the compound to cure into a self-supporting casting having a negative impression of said surface; removing the casting from said surface of the test specimen; applying a second casting compound of a contrasting color to that of the first casting compound over the negative impression on the casting; allowing the second casting compound to cure into a protective covering on the negative impression on the casting while forming a positive impression in the covering as a negative image of the negative impression on the casting; cutting the casting and protective layer thereon in a plane corresponding to a surface of interest of said test specimen to obtain a test piece having a profile characterised by showing a casting layer and a covering layer sandwiching the negative impression therebetween; and measuring the negative impression in the casting to determine the geometric feature of said surface of the test specimen corresponding to said plane of cutting.