Fiberglass Roving & Silent Packs

ISW SILENT PACKS are used for packing internal exhaust / muffler components, auto compartments/cabins or even residential cinder blocks to provide excellent long term sound absorption.  SILENT PACKS are made from a continuous filament, single-end roving product manufactured with boron-free modified E-Glass (E-CR) composition fibers.  ISW’s Fiberglass E-CR Roving is engineered to provide excellent sound absorption in high temperature and corrosive exhaust systems.


  • ISW’s E-CR Fiberglass Roving is OEM approved and Made in the USA.
  • The sizing chemistry of the individual fibers produces pillows that are uniformly volumized with a lofty roving that has low fuzz and fly for efficient long term acoustical performance.
  • Has higher thermal and better chemical durability than basalt or standard e-glass.
  • Is less sensitive to high humidity versus other leading E-CR roving.
  • Increased fiber strength over both basalt and standard E-glass fibers even at elevated temperatures.
  • Reduces opportunities for shell corrosion caused by fiberglass mat.
  • Is designed to easily open to provide uniform and effective acoustic properties.
ISW texturized fiberglass roving


  • Are filled with leading edge volumizing equipment to precisely fill bags to the correct weight with a lofty fiber distribution to conform to OEM requirements.
  • Are an alternative to expensive direct filling equipment and tooling costs.
  • Are designed to effectively fill stamped or tubular exhaust components.
  • Offer a convenient fill that is more efficient to install than fiberglass mat without the dust and mess.
  • SILENT PACKS can be made from:
    • Woven or Mesh E-glass fabric material formed into pouches, tubes or custom shapes sewn with a fine polyester thread that will emit little to no smoke or odor at start up.
    • Low cost polypropylene bags that burn off at start up.
  • Use ISW Stainless Steel Wool Tubes, wraps or end cap insulators for improved long term durability.
Max Service Temp 735°C / 1355°F
Softening Point 916°C / 1681°F
Thermal Expansion Coefficient 5.46 10-6/ °C
Fiber Glass Density 2.63 g/cm3
Average Fiber Diameter 24 µm
Pristine Fiber Strength 3500 Mpa
Reflective Index 1.56
Roving Tex, nominal 4800  g/km