To achieve maximum loft and insulation, down must be dry and uncompressed. Even if sleeping in a dry tent your sleeping bag can still get damp or wet from condensation; vapour leaving your body passes through the down, and condenses on the outside and inside of your sleeping bag shell. The condensation that forms on the inside of the shell is absorbed by the down reducing its loft and warmth.
Over several days of packing and unpacking a sleeping bag, wet down mixes with dry down affecting its ability to loft. By the end of a long trip it is not uncommon for a sleeping bag to have decreased in warmth significantly because the down is damp, reducing its loft and its ability to insulate properly.
At Sea to Summit we have solved this problem with our 3D NanoShell and ULTRA-DRY Down.
The NanoShell Face is a 20 denier fabric that is highly breathable, water resistant and treated with a Nano DWR for unparalleled performance in wet and windy conditions .
The 3D Barrier is a non-woven silicone encapsulated 3-dimensional layer under the NanoShell Face.
Together they form the 3D NanoShell, a condensation management system that insulates, repels water and protects loft.
The 3D NanoShell provides a 3-dimensional layer between the cold external environment and the warm down inside your sleeping bag. When vapour passes through the down, it enters the 3D Barrier, before exiting the breathable NanoShell Face fabric.
Any condensation that forms under the NanoShell Face fabric is separated from the down by the 3D Barrier. Due to its hydrophobic nature, this 3D Barrier traps the condensation preventing this moisture from mixing with the down layer .
When conditions become favourable the 3D Barrier also promotes fast evaporation expelling moisture to the outside preserving dry and fully lofted down .
Over several days of usage, the weight of absorbed moisture and the associated drop in insulation that other bags would suffer makes 3D NanoShell the wise choice for expeditions.