Suppose you are out on a hike on a nice sunny day when you look up and see those clouds. Yeah you know those clouds. The ones that you already know its gonna start to pour down any time and most likely soon. The first thing that goes through your mind, how will I stay dry? Do you have your shell layer and how well is it going to hold up?
The last layer of your layered clothing system or shell layer has 2 main purposes. To keep you dry and to block the wind all while still being breathable. While there are some that will do better at keeping you dry longer, none of them will keep you completely dry for long periods of rain. This is especially true if you are actively hiking for very long.
The truth is no shell fabrics are completely waterproof no matter how they advertise it. They will all leak when exposed to enough water pressure. The purpose of this article is to outline the differences in different shell fabrics and help you stay dry longer.
The are 2 types of shell fabrics, water resistant shells and water proof breathable.
Water Resistant Shells
Wind shells are ultralight and very packable. They allow you to breath very well but are not very water resistant. Wind shells work great to block the wind or when it is raining but too hot and humid for water proof shells.
Soft shells are still great are breathability just as wind shells are but are usually a little more durable. They work great in cold weather to clock the wind or for dry snow.
Neither of these 2 types of water resistant shells are very waterproof and typically do not dry very fast after getting wet. When untreated they are no better than a normal shirt so be sure to treat these shells with some form of durable water repellent solution (DWR).
Waterproof Breathable Shells
Waterproof breathable shells are much better at keeping you dry from the rain than the water resistant shells. They are however barely breathable which will cause you to get soaked from the inside with sweat. Don’t let the word waterproof fool you, they will eventually start to leak. Some will definitely last longer before leaking though.
Waterproof breathable shells usually have a DWR coating which if worn out will tremendously impair the breathability of the material. Even at its best you will most likely sweat much faster than can be evaporated though the shell. Your only hope is if you are doing less than even moderate activity or if its not hot weather.
PU-ePTFE is branded as Gore-Tex and was the first waterproof breathable material. This has helped it to still remain the most know. Gore-Tex has an additional polyurethane coating to protect it from the environment. Because of this, the breathability of this material suffers greatly.
ePTFE, branded as eVent, is the same thing as Gore-Tex without the outer polyurethane coating. In place of the PU coating it has an oil repelling coating that protects it from the environment. Because of the missing PU layer it breathes very well.
Polyurethane only (PU)
When by its self polyurethane cannot be as thin as it is when it is just a coating so it is much thicker. This makes it terrible for being breathable. Polyurethane can be laminated to another softer fabric making it less stiff and crinkly.
Polypropylene is more breathable than Gore-Tex but not as well as eVent. It can also be very expensive. But there is a laminate version that is much cheaper. The down side is the laminates usually do not fit very well and are limited in style
Some shells have venting features that will help with staying dry on the inside by letting cooler air in and letting the hot humid air out. Examples include arm pit zippers, chest vents, and 2 way center zippers. The down side is this creates more points for water to enter because the water tight zippers are not actually water tight.
Expert Tip: Wear a ball cap to keep the hood out of your face.
Now that you know a little more about the shell layer materials and functions you should be able to choose the best shell layer for your needs. If you found this article helpful please be sure to share it with others so that they too can be helped.