This discussion of various bag/cloth filter degradation mechanisms is mostly common sense. However, this information is occasionally lost in the subtleties of real-system operation. Although this paper is written with reference to fluidized-bed combustion (FBC) applications, the insights are generally applicable. For enumeration of particular filter fabric and baghouse experiences in FBC applications, the reader is referred to a report by Davy McKee Corporation (no date). A fabric filter is a composite matrix of fibers oriented to retain the dust particles from dust-laden gas. The cleaned gas passes through the fabric filter; the retained dust particles are deposited on the surface of (and within) the fiber matrix. The retained dust can be later removed through mechanical means. The fabric may be made of any fibrous material, spun in yarn, and then woven, impacted, needled, or bonded into a felt. Deep penetration of aggregated fine particles, lack of dust removal during filter cleaning, and chars or condensed aerosols may contribute to the increase in pressure drop across the filter. This increases the filter operation power consumption and, consequently, reduces the filtration capacity. The phenomenon of building a high-pressure drop in spite of filter cleaning provisions is known as blinding. In order to maintain an acceptable gas throughput, blinding problems must be addressed. Recommendations are given: maintain temperature above dew point, use filter aids, by-pass filter during start-up or operational upsets, etc.