[pct-l] To waterproof or not to waterproof (ye old sleeping

[Paint Your Wagon]

Eric,

Thank you for your perspective.
I checked the waterproofing purpose of the NIKWAX product and determined it 
is the good "stuff",
the heavy duty "stuff".
It's meant for synthetic tents, awnings, marquees, rucksacks, panniers, and 
camera bags.
No clothing mentioned.
So- I will use it, as I intended to; for my tent and fly.
Treating the sleeping bag would backfire.
Now I know.

Thank you,

<>Paint<>

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

Eric wrote:

>>> 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 <<<