Polyester Felt is nominally rated. The fabric is singed to prevent breaking of fibers during filtering. Polyester felt is not as easy to clean as mesh but can still be cleaned. Generally, this felt is meant to be thrown away after it is clogged. Polyester has an excellent rating with water, vegetable oils from animals and plants, petro-oils, organic solvents and micro-organisms. Polyester has a good rating with Alkalis, Organic acids, mineral acids and oxidizing acids.