Which is Best: Hydrophilic or Hydrophobic? No, it's not high school science class. It's Fabric Fiber 101. Hydrophilic fabrics attract moisture and elongate. These fabrics may become unstable and puddle, sag, or ripple when the humidity reaches 40%. Some natural hydrophilic fibers, such as wool, cotton and linen, may return to normal size and shape when humidity levels drop, but you need to keep in mind that HVAC units are often turned off when a building is closed (such as weekends and holidays). Synthetic hydrophilic fibers such as rayon, viscose, acetate and spun nylon, have very little memory and will not return to their original size and shape once exposed to humid conditions. When a fabric isn't stable, stretched vertical application is difficult. Hydrophobic fibers such as polyester, acrylic and modacrylic, have poor absorbency and are, therefore, stable. When a polyester fabric, for example, is stretched over an acoustic panel, it will remain tight and resist puddling even in the presence of high humidity. Even though synthetic fibers are the most suitable for stretched applications, it is not always possible to use a 100% synthetic fabric. An excellent option is to use a fabric blend, containing at least 60% polyester, acrylic or modacrylic. The higher the percentage of natural fibers, the less stable the fabric and the less suitable for stretched panels. HOME Copyright © 2003 Acoustics.com