Preventing condensation in down bags

[Eric Blumensaadt]

A nice solution to preventing vapor moisture condensation inside the outer shell of down bags is using a synthetic insulation quilt as made by Mountain Laurel Designs (MLD).

They have 3 different weights of insulation using Climashield which is about the best synthetic insulation for retaining loft after repeated stuffings. I think I’ll get the lightest version.

The body vapor condenses in the colder MLD “over bag” quilt and, being all black, it dries faster when hung out to dry.

**You can also choose an insulation thickness that will help extend the temp range of a 3 season down mummy (or quilt) and kill two birds with one stone.

[Stephen M]

Have tried both a 30f, 40f, and 50f as overquilts. The 40f is the best option to me as its warm enough without too much bulk to use in summer.

[r m]

Can confirm success using a MLD spirit over a down bag on one trip :) I went with an XL in the middle warmth thickness, after ~1 week camping in a snowy valley with not much in the way of sunshine, the APEX insulation felt like it had hard lumps in it, and my down bag felt quite dry and no lumps. I guess during the day the quilt never got warm enough for the ice to melt out, so more got added each night.

I’ve since replaced that down bag with a regular wide EE down quilt and a superlight bivy. I’ll see how I go.

[John F]

Eric – any updates on your experience with the MLD climashield sacrificial synthetic over quilt?

[Eric Blumensaadt]

John,

After using an old duck down mummy shaped over-quilt and finding it just too much bulk and weight for me I am going to make a VBL suit from light silnylon. I think this is the best way to go instead of a VBL bag. It permits me to add puffy clothes when (IF) I approach -20 F. or lower.

A synthetic over-bag is even more weight and bulk than the mummy shaped duck down over-quilt.

 

 

 

[D M]

In 2016 I was on the PCT and needed more warmth and less condensation in my FF 20 degree so I went to town, found a fabric store, bought eight snaps and a yardage of soft fleece and sewed an over bag by hand together. Works perfect and cost me less than 20 bucks. Weighs 21 oz.. And rolls into a 6 inch X 14 inch package.

[Eric Blumensaadt]

@ DM,

Smarty Pants!

“Necessity is the mother of invention.”

 

[D M]

I love you too Eric. :-)

[Seth D]

Warmlite vapor barrier suit for me. Cuts condensation in my bag/bivy great. The only thing left is to figure out a way to keep your breath off everything.

[Edward John M]

Just wear an avalanche mask Seth, problem solved if you direct your moisture laden expired air away to the outside, they weigh very little and don’t take up much space

[Kevin Babione]

@Seth – I sleep in a hammock and just saw that Dutch came out with a new product to solve the issue of the moisture (or at least some of it) you generate when sleeping:  The Breathalizer

His Chameleon hammock has, as an option, a top cover with a vent that you put over your head.  The Breathalizer redirects your “exhaust” to the vent and keeps all of that moisture from being trapped around your top quilt.  Very clever!

For those of you in tents/tarps – I wonder if you could develop a similar lightweight divider between your head and your body and how much that would help to keep your top quilt/sleeping bag dry.

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