A water proof membrane
made by Gore
The membrane is made of micro pore
s and works on the principle
that water droplets
are larger than air molecule
s (yeah, I know air is a mix of oxygen
and other stuff
, but we'll call it an air molecule!). The pores are large enough to let air pass, but too small to let water through. Therefore water droplets cannot pass through
the membrane, whereas air molecules and vapour
can. We say that the membrane breath
The Gore Tex membrane is laminated onto an outer shell, usually some sort of polyester fabric, which is heavily impregnated.
The membrane is made from the same material as teflon, and withstands extreme temperatures.
There exists three different types of Gore Tex shells:
- 2-ply: in a 2-ply shell, the membrane is laminated onto an outer shell, and an inner mesh hangs loose to protect the mebrane, which is otherwise unprotected.
- 3-ply: in a 3-ply shell, the membrane is laminated onto an outer shell and an inner protective lining. If the inner lining gets moist (ie. from sweat), it can freeze, this is usually only a problem when you're high up in the mountains.
- PacLite: the membrane is laminated onto an outer shell, and small rubber pads are glued directly onto the membrane to protect it.
The 2-ply construction makes for a soft, quite silent, shell, often used in skiing clothes. 2-ply clothes do not withstand the severe abuse of a heavy backpack as the membrane will be rubbed between the inner mesh and your back.
The 3-ply construction resits much harder use as the 3-ply shell is laminated together into one sheet. This makes it a bit thicker and slightly heavier, and it doesn't breathe as good as a 2-ply. Still, a 3-ply shell is the most allround Gore Tex shell you can find.
The PacLite is very light and packable and also the most breathable. It's a very good choice for hiking, although the rubber pads will be worn out after a while. The membrane is also exposed (as in the 2-ply), so it will not endure the same hard use / abuse as a 3-ply shell.
In the winter 2000, Gore released a new membrane -- Gore Tex XCR, the Extended Comfort Range membrane. This is made as a normal 3-ply shell, but the membrane breathes about 25 - 40% more than a normal 3-ply. To put it another way, the XCR breathes almost as good as a 2-ply or a PacLite shell, making it a very good choice for heavy daily use.
See also: Conduit, Dermizax.