[pct-l] To waterproof or not to waterproof (ye old sleeping bag) that is thee question.

[Eric Lee]

Paint wrote:
>
What say ye in regards to waterproofing a (my) sleeping bag?
Pros? Cons?
>

You're right that any waterproofing treatment will reduce the breathability of the bag to some degree.  The amount of reduction depends on the impermeability of the treatment.

A mylar emergency blanket is total solid and non-breathable so it's going to produce a massive condensation problem.  (It's surprising how much water escapes your body when you're sleeping!)  On the other hand, it'll give you a lot of warmth both from reflecting radiated heat and also from trapping that water vapor so it can't escape and carry heat with it.  Winter mountaineers use that technique a lot - it's called a vapor barrier layer or VBL, but the correct way to use it is to put it *inside* the sleeping bag so that you marinate in your own juices but your bag insulation stays totally dry.  Yucky but effective.

A spray-on water repellent is not going to be nearly as impermeable as mylar but it's hard to say just how breathable or not it might be.  If you can find a product that says it's safe for use on Goretex jackets that would probably be the best option since it'll be designed not to overly-damage the breathability of the material.

Eric