Measuring Methods of Paper Formation

Abstract

One big advantage of using the β-rays in measuring paper formation, instead of light which has been commonly used, is that the distribution of basis weight in paper can be directly measured, not affected by the color or the density variation of paper. However, one of the disadvantages in this method is that the size of measuring spot must be set much larger than that in the light transmission method. So we have developed a new measuring method, using the β-rays within the safe activity to handle, in which the basis weight variation can be measured of such a small area of approximately 25×25μ as not to be measured by the light transmission method. In this method the specimen is radiographed by the β-rays plastic sheets (poly-methyl methacrylate) containing Carbon 14 ; the transmission of the β-rays is photographed by Kodak "Crystallex" X-ray film; then the basis weight variation is measured by the optical density variation in the X-ray film. In this method paper formation can be measured within the measuring error of 4 to 5% under careful operations. Some applications of this method are described.