Filter Bag Finishes

Sly’s finish treatments can greatly improve your filter bag life, cake release, resistance to abrasion, static dissipation, and protection from harsh application conditions. Our fabric treatments combined with various medias of different types and weight can provide the best possible filter media choice for your demanding application. How a fabric filter media is finished depends upon the desired physical specifications, surface finish and requirements of the application.

Types of Finishes for Fabric Media

Plain: (PL) No finish added

Singed (SI) This process involves exposing the surface fibers to an open flame to melt back the loose fiber ends to which dust particles could adhere. The singing improves dust cake release and adds very little cost to the product. This is the most popular type of finish used today.

Glazed (GL) Known as calendaring, this process involves putting the felt through two heated rollers that melt back the loose surface fibers and can also compress the felt to smooth the surface and improve dust cake release.

PTFE membrane / Pristyne® PTFE / Tetratex PTFE: A thin laminate of Teflon® is thermally bonded to the outside of the filter bag. PTFE membrane is used to greatly improve both the filtration efficiency and the cake release ability of the filter bag. The membrane is relatively expensive, extremely fragile and care must be taken when handling and installing this type of filter bag. The PTFE membrane can be added to most types of fabric filter media and offers the optimum filtration efficiency.

Fire Retardant: (FR) Chemical sprayed on surface treatment designed to reduce the probability of a spark igniting the filter media that has been treated. The treatment does not “fire proof” the filter media, but offers a modest level of protection against an occasional spark.

Acid Resistant: (AR) Sprayed on treatment improving media fabrics ability to resist acid attacks.

SlyCharge (EX) A stainless steel grid patterned scrim is manufactured inside the felted fibers of the media. Anti-static design exceeds standards for static dissipation media below 10⁶ resistivity. Due to the unique design and proprietary needling technology used by our media supplier, the potential for product contamination is eliminated. SlyCharge has been accepted by major U.S. users within the food, power generation and plastics processing markets. The static conductivity capability is durable and works like new, even when covered with dust.

  • SlyCharge is available in a variety of felt designs and finishes such as ST-01, SlyHE (high efficiency) and ST-04 (Code 9).
  • Some successful applications of SlyCharge (EX) include: calcium fluoride & silica, aromatic hydrocarbon resin, silica dioxide (fumed silica), paper, and barite w/polypropylene glycol coating.

SlyTech-01 (ST-01) An Oleophobic dust release fluorocarbon resin treatment that is engineered for the efficient separation and release of wet, oily, fatty, sticky and agglomerating dust. Because the base felt is totally submerged in the chemical bath during the manufacturing process, each fiber is encapsulated with the treatment providing excellent dust release from both the surface, as well as the depth of the filter media. SlyTech-01 is also good for non-continuous processes, where the temperature may drop near to the dew point. The ST-01 finish helps prevent the uptake of moisture by the needle felt, thus reducing the danger of excessive dust deposits and caking.

  • Advantages of ST-01: Superior release of difficult dusts; reduced blinding and clogging; higher flow rates; longer bag life; lower pressure drop
  • Available medias: Polypropylene, Polyester, Homopolymer Acrylic, Aramid, PPS (Ryton®), P-84 (Polyimide) felts. For high temperature felts, see SlyTech-03 (ST-03).
  • Some of many successful applications include: prill, poultry manure, granulation, sugar, synthetic silica gel, single super phosphate (Fertilizer) and many more.
  • FDA approved version available (SlyTech-02) for food processing industries. ST-02 is able to effectively release dust cakes with natural fats and oils, including cheese whey, powdered milk, yeast, starch, flour, sugar and egg.
  • Information sheet

SlyTech-03 (ST-03) PTFE surface treatment is a solution for cake release problems associated with high temperature felts. ST-03 provides a high degree of surface separation with excellent cake release. PTFE resin is thermally bonded to the cake side fibers to form a smooth, high temperature, chemically stable surface. By promoting surface cake formation, the ST-03 treatment prevents clogging and blinding of the felt media and extends filter bag life.

  • Advantages of ST-03: Promotes surface cake formation; facilitates dust cake release; higher flow rates; longer bag life; lower pressure drop; high separation rates
  • Available medias: ST-03 is normally applied to the four major high temperature fibers. These are Aramid, P-84® (Polyimide), PPS (Ryton®), and PTFE. Pure PTFE resin is used as the base for ST-03 in order to resist high temperatures and withstand aggressive chemistry.

SlyTech-04 (ST-04) Commonly known as Code 9, this finish is a non-stick cake release treatment which provides resistance to abrasive dusts.

SlyTech-05 (ST-05) Teflon finish for high temperature applications when using woven fiberglass fabric. Works well for difficult corrosive gases because of very good chemical resistance and for its ability to resists clogging while enhancing bag life.

SlyTech-08 (ST-08) An extra heavy coating of ST-01 (Oleophobic) for extremely difficult, agglomerating dust.

SlyTech-09/SlyTech-10 (ST-09/ST-10) Spark resisting surface treatment for polyester felt. ST-10 adds a bath treatment of ST-01 (Oleophobic /see above) for additional repellency and cake release.

SlyTech-11 (ST-11) Reduces the adverse effects of hydrolysis on aramid. SlyTech-11 is highly effective when used with PTFE scrim support.

SlyTech-12 (ST-12) Stainless steel fibers added to the base felt fibers before the media is manufactured to conduct static electricity (Anti-Static). Often used in conjunction with a ground wire to dissipate static accumulation on the filter to the tube sheet of a grounded baghouse.

SlyTech-15 (ST-15) Powdered polymer surface repellency coating designed for sticky and/or oily fibrous dust. This treatment is the optimum surface release available for fibrous dust.

SlyTech-16 (ST-16) Provides a silicon treatment to the surface of the filter bag. Often called “siliconizing” or “egg shell” finish (similar to glazing), this is a heat treatment designed to provide a smoother bag surface to assist in cake release for sticky and difficult to remove materials.

SlyTech-17 (ST-17) Acrylic-foam treatment that is applied to the surface of the media. The foam is spread on the surface and cured to provide a smoother and licker surface for sticky dust release and also provides sealing of pores in the bag to create a slightly better efficiency for fine dust collection. Acrylic foam treatments are rarely used in today’s applications since PTFE membrane technology has come down significantly in pricing and provides much better overall efficiency and dust release performance.