In the case of POV test paper which we have made before (this journal, 28, 403 (1975)), the effect of glass fiber seems to depend on its acids properties. Because, the surface of glass fiber forms Lewis acid, and it was capable of being acid catalyzer for hydroperoxide-potassium iodide reaction. Similarly, silica, alumina, asbestos, etc. can also be used as the acid catalyzer by applying them on a piece of paper or plastic film together with potassium iodide and starch.