Pertex Equilibrium: Fabric Technology and Performance Overview
Pertex Equilibrium is a woven 100% nylon (nylon 6.6) from the UK-based looms at Perseverance Mills. Fabric weight is 90 grams per square meter, which equates to unlined shirt and jacket weights coming in at 8 to 15 ounces, with microfibre pile- or tricot-lined garments weighing 4 to 8 ounces more. Most garments using Pertex Equilibrium are manufactured and distributed in the United Kingdom. U.S. Manufacturers include GoLite and Marmot and are expected to increase in 2004 and 2005.
Equilibrium’s unique feature is its denier gradient design, with the goal of passively moving moisture from the inner face to the outer face of a fabric with a denier (and thus, capillary diameter) gradient driving capillary action. By no means the only fabric on the market with this goal, it is certainly one of the lightest and most resistant to abrasion.
The primary application for Pertex Equilibrium is "soft-shell" apparel to be used in situations where water and wind resistance is needed for high exertion activities that require fabric breathability.
The inner face of the fabric is woven with larger filaments (comprising a low fiber surface area and large capillary diameter), while the outside face is constructed with smaller filaments (comprising a high fiber surface area and small capillary diameter). Passive movement of liquid moisture occurs primarily by capillary action from small pores to larger pores. Thus, Pertex Equilibrium is designed to manage both external and internal moisture appropriately for active use in foul conditions.
Pertex Equilibrium Construction
Pertex Equilibrium is designed such that external moisture (precipitation) should have a difficult time breaking the capillary forces on the fabric’s outer face. And, the moisture that does break through should have a difficult time migrating inward (against both capillary and vapor pressure gradients). On the other hand, moisture that comes into contact with its inner face (i.e., sweat) should effectively be driven to the outer face, where it is free to evaporate to the atmosphere.
Insulation and Breathability
Because the inner face is textured, Pertex Equilibrium provides some insulating ability. However, because Pertex Equilibrium contains no coatings, laminates, calendaring, or membranes, moisture vapor is freer to move through the fabric and breathability is greater, than for waterproof-breathable fabrics, or woven nylon and polyester fabrics that are impregnated with water-resistant chemicals or calendared.
Another unique feature of Pertex Equilibrium lies in its textured inner surface – resulting in the fabric staying off the skin surface, which facilitates moisture vapor permeability (breathability), sweat evaporation, and wicking into the fabric. In short, this type of inner fabric face construction makes Pertex Equilibrium quite comfortable when worn next to the skin.
The outer face has a tight enough weave (with a sun protection factor of 30+) to significantly resist wind and moisture. In fact, Pertex Equilibrium offers about 10 cfm of wind resistance – significant for a fabric that is this breathable. We found that Pertex Equilibrium-shelled clothing systems are more than sufficient for sloughing off winter snow in cold temperatures, and we highly recommend Pertex Equilibrium as an outer shell material for winter backcountry activities. In addition, they were breathable enough to be worn close to the skin – we’ve worn the Pertex Equilibrium-shelled and microfibre pile-lined Rab V-Trail Top and Smock under a wide variety of conditions as a next-to-skin base layer and found them to be effective at preserving a relatively dry next-to-skin environment, even during high levels of activity.
Pertex Equilibrium provides a reasonable degree of rain resistance. We wore Pertex Equilibrium shells in all kinds of weather from fine mist and fog to heavy driving rain. Not surprisingly, we found one combination of conditions where the wetting rate of Equilibrium could not be held back by the evaporation rate from body heat – cold temperatures (approximately 38 to 48 degrees) combined with heavy precipitation as rain or wet snow. In this respect, Pertex Equilibrium does not distinguish itself from other soft shell fabrics, such as Schoeller Dynamic or Cloudveil Inertia. However, Pertex Equilibirum enjoys significant advantages over both of those fabrics – less insulation and better wind resistance while still maintaining excellent breathability. In that respect, most of us found that Pertex Equilibrium struck a more meaningful balance of storm resistance and breathability for a fringe-conditions soft shell fabric.
We’ve been testing Pertex Equilibrium garments since the fabric’s release. We’ve tried unlined garments (GoLite Vitality Jacket) and lined garments (Rab V-Trail Top and V-Trail Smock). They are among the most comfortable “soft shell” garments we’ve worn, in terms of their ability to regulate your body’s next-to-skin microclimate while active, and provide “good enough” protection from the elements (wind, rain, and snow) for most conditions. Although not as light as a tightly woven nylon or polyester microfibre wind shirt (e.g., Montana Aero, GoLite Wisp, or Marmot Chinook), Pertex Equilibrium garments can be worn in a wider range of conditions, and tend to be more versatile. So, before you discount their use on weight alone, consider how a Pertex Equilibrium garment might fit into your overall clothing system. Lined garments, in particular, including the Rab V-Trail Top and the Parrot Conure Pull On, make for excellent base layer choices in the fringe (spring and fall) and winter seasons.
Pertex Stretch Equilibrium, to be released in 2004, will address many of the issues brought on by Equilibrium’s opponents and stretch woven soft shell advocates – comfort. The introduction of Stretch Equilibrium will result in greater latitude of styling, offering garments that can be cut trimmer – and thus perform more efficiently (lighter weight, better integrated with existing layers, less fabric to catch on bush and rock, etc.) – without restricting mobility. Currently, GoLite is the only U.S. manufacturer with a meaningful Pertex Equilibrium product development initiative targeted specifically at backpackers and other fast-and-light enthusiasts. Marmot will introduce a Pertex Equilibrium clothing line in Spring 2004. Look for other U.S. manufacturers to introduce Pertex Equilibrium garments this fall, with Stretch Equilibrium products coming to the U.S. market in 2005.
About Backpacking Light’s Fabric Technology and Performance Overviews
In 2004, Backpacking Light launched an initiative to provide consumer education about high performance textiles and materials used in apparel and other soft goods manufacturing. We are pleased to launch this initiative here with Pertex Equilibrium. Fabric Technology and Performance Overviews are in no way sponsored by fiber, textile, or end use product manufacturers, and the appearance of logos, product examples, or discussion of same in the text does not constitute an endorsement of those products over those that may not appear herein. This is an independent review. We have consulted a variety of sources to compile this information. Those sources include technical data sheets from manufacturers, textile testing laboratories and design consultants, and end users. In addition, we have evaluated fabric performance as detailed herein using commercially available products manufactured with the textile described. Reviews of those products and an analysis of their specific features may be found elsewhere at BackpackingLight.com.
Stay tuned for other Fabric Technology and Performance Overviews, coming soon:
- Pertex Quantum
- Pertex Endurance
- Nextec EPIC
- Schoeller Dynamic
- Schoeller 3XDRY
- PrimaLoft Sport, PrimaLoft PL1, and PrimaLoft PL Lite
- Polarguard 3D and Polarguard Delta
- Silicone-coated nylons