The homogeneity of filter media is important for material selection and quality control. Cloudiness or formation is a term that describes deviations from homogeneity.
There are different image analytical methods to measure cloudiness reproducibly. However, cloudiness measured with different instruments is usually not comparable. We have developed a theoretically based cloudiness index and a method to measure it from the power spectrum. Our paper »Assessing Cloudiness in Nonwovens« (FILTECH, 2022) covers more practical aspects of estimating the cloudiness index. We applied the cloudiness index in the project »ProQuIV« (Production and Quality Optimization of Nonwoven Infection Control Clothing).