Good hardshell/softshell tech info!

[RideT61]

The information below starts a bit slow but gets more interesting as you go on. Any thoughts????

 

Technical Clothing Definitions and Concepts

 

 

I Definitions as commonly used in the outdoor industry

 

A Water resistance (waterproofness) - the ability of a fabric to prevent water from passing through [measured in millimeters (mm) of water].

B Water repellency- The ability of a fabric to repel water or cause it to “bead up” on its surface

C Wicking-the ability of a fabric to absorb and spread out moisture (perspiration) thus increasing surface area and evaporation

D Vapor permeability (breathability)- The ability of a fabric to pass perspiration in the form of water vapor (measured in grams/square meter/24hrs).

E Air permeability (wind resistance)- the ability of a fabric to prevent air/wind from penetrating it. This is measured in ft3/ft2/minute but can be converted to mph for easy comparison.

 

II Layers

A Base layer- The layer of clothing worn next to the skin. It’s function is twofold. First, it should carry perspiration away from the skin to promote evaporation. In addition, this layer should provide a level of warmth appropriate for the activity level and weather conditions. Ideally, this is the only part of your layering system (traditional hardshell or softshell) that should absorb any water.

1 Lightweight- Summer/cooling- In warmer temperatures fabrics that are high wicking and fast drying are ideal. This is because evaporation is a cooling process and therefore a fast wicking/drying garment help keep the user cool. As a result, synthetic fibers are ideal for this because they do not absorb water into the fiber and therefore dry quicker.

2 Mid and Expedition weight-This base layer used in cooler temperatures provides some degree of insulation and a moderate amount of wicking. Because these garments are worn at cooler temperatures, the cooling provided by ultra-wicking fabrics is not necessary and can even chill the user (think about the last time you took your sweaty pack off on a chilly day). As a result, wool, which absorbs some water but retains its warmth when wet, unlike cotton, is ideal. The wool should however be very thin otherwise it will take too long to dry. In the last few years companies have learned to knit wool fibers into much thinner fabric making this possible. Additionally, this layer should have a snug fit to maximize thermal characteristics and help drive moisture out.

B Insulation- Comes in a variety of forms (fleece, down and synthetic fill jackets) and is worn as a second layer in the traditional hardshell layering system as well as “over the top” in soft shell/nontraditional layering systems.

C Soft shell- Garments generally made of tightly knit fabrics which are sometimes bonded to a woven face fabric. Softshell fabrics have good water resistance due to their tight knit construction and are water repellent because they are treated with DWR. Soft shell fabrics are significantly more breathable than hardshell fabrics when they are without a laminate because they allow air (wind) to pass through the fabric and transport water vapor away. This means that if you can’t blow through the fabric and feel you’re your breath on the other side it will likely breathe no better than a hardshell. Ideally, no part of a soft shell garment should absorb water! Water repellency is very important to the function of these fabrics. If either the faceside or backside of your jacket “wets out” an impermeable water layer is formed which prevents perspiration in the form of water vapor from passing through it. This means a wetted out jacket or pant is no longer breathable.

D Hard Shell (waterproof-breathable)- A waterproof garment that allows the passage of some moisture. While these garments do breathe better than rubber and coated nylon they are still do so relatively poorly (a plastic bag is approximately 40% as breathable as Gore Tex XCR in certain test methods). Because of this, these garments are not ideal for activities that require a high level of exertion. It is for this reason that softshells were originally developed. Like softshells water repellency is also very important to their performance. If the outer face fabric has wetted out the garment will no longer breathe no matter how good the laminate/waterproof-breathable layer.

 

III Layering systems

The traditional hardshell/waterproof breathable layering system starts with a wicking layer on the bottom, followed by a layer of insulation with a hardshell over the top of everything. This layering system is ideal for low energy activities or in very cold conditions where overheating (and therefore sweating and moisture dissipation) is not a concern. It should also be noted that in very cold conditions where sweat management is not an issue the hardshell is often unnecessary because there is little danger of getting wet.

The traditional hardshell system does not perform as well in warm and/or wet conditions because while the hardshell does keep moisture (rain) out, it also keeps moisture (sweat) in. This is true for two reasons:

First, the breathability of a hardshell (or softshell, although it is significantly better than a hardshell because it is air permeable) increases with the differential temperature across the fabric. This means that if the temperature inside your jacket is 100F and 40F on the outside (60F difference) it will breathe better than it would if it was 70F inside the jacket and 40F on the outside (30F difference). This is important because while we can not control the temperature outside our jacket we can control the temperature inside it by wearing it closer to our body. For example, a hardshell jacket worn over a big down jacket has a lower temperature inside it than if worn directly over the baselayer.

The other condition that helps drive moisture through a hardshell (or softshell, although it is easier to do because it is air permeable) is a large difference in humidity. As a result, hardshells breathe best when the humidity is low. Unfortunately we rarely have a need for a hardshell when the humidity is low because rainy weather is humid weather. This means that hardshell really doesn’t start breathing well until it is already clammy inside your jacket.

It is because of the concepts explained above that soft shells and “over the top” insulation such as belay jackets are gaining popularity. Unfortunately many outdoor companies have yet to understand the physics behind this process and are continuing to design for fashion instead of function. If you really want to manage moisture well in the outdoors, you need to understand the concepts above and adjust your layers accordingly.

[bonathanjarrett]

I think you nailed it! Well articulated.