This unification concerns the method for determining the corrosion resistance of a refractory material, i.e. its ability to resist penetration and/or destruction at high temperatures by aggressive substances, solid at room temperature. 2 The test consists of placing the aggressive substance inside a cavity made in the material under examination, heating it at a given temperature for a certain time and finally detecting the effects after cooling. 3 The type, composition and quantity of the aggressive substance, as well as the duration of permanence at the maximum temperature, are not established by this unification, but must be established on a case-by-case basis. 4 The method is applicable to formed refractory products (see UNI 4450, points 6 to 10).