I hear a lot about storing sleeping bags in cotton sacks for breathability purposes. I store all my gear in large plastic containers. My containers are large enough so there is no compression, but now I'm worried about breathability?
Submitted by - Marty - Derry, NH
Short answer: Yes, breathability is important, especially for long-term storage. When you use a sleeping bad, your body gives off moisture vapor, which can get trapped in the insulation. It's a small, usually unnoticeable amount, but unless that vapor gets the chance to evaporate (which it does by exposure to air) it can get trapped inside your bag and lead to loss of loft and a gross, mildewy smell.
I store my bags in my basement, which can sometimes get damp. My solution is to a) air my bags out completely in the sun after each trip, b) store them in their big cotton or mesh sacks, and c) place those sacks into big plastic bins with NO LIDS. I can get two or three bags (standing upright) in each bin. This keeps them protected from the sometimes damp basement floor, but also allows air to freely circulate. Hope this helps!