Waterproofing Sleeping Bags
The standard outer fabrics on our mountain sleeping bags are Drishell and Ultrashell. These fabrics are water resistant, highly breathable and very light. We think this is the best way to keep the down or synthetic insulation we use in our sleeping bags dry. However, proofed outers are not perfect. Bags made with Drishell, Ultrashell and similar fabrics do carry a small weight penalty, and they do let water in at the stitch line (e.g. if you are sleeping in a puddle). Bags can also be made with complete taped outer shells, which will be proof against nearly all situations, but the weight penalty of an extra skin is considerable.
Our ultralight Minim sleeping bag range uses 10X, M1 and MX microfibres, fabrics that are extremely light. For customers who require a greater degree of water-resistance, some of the Minim range is offered with the option of a Drishell outer.
If there's a serious danger that the sleeping bag will get wet we recommend using synthetic insulation such as in our Zeta synthetic sleeping bags. They are designed for big wall bivouacs in damp conditions.