VBL adds how much to my quilt?

[chris Mcfarland]

I use a 40* revelation quilt with 30% over fill down to about 32*. It has just shy of 2" loft or 8.75oz of high fill down. Has anyone used a vbl to stretch this or something similar into the mid 20s or is that overreaching? (Assumeing i have sufficiant head and ground insulation) i have a warmer bag (20* FF swallow) i just want to ask some advice before i end up doing midnight situps while heating a water bottle. :)

[drowning in spam]

Mid 20's is about as far as I'd want to push a quilt because of drafts, even if I'd still be warm overall…just those drafts grab my attention too well. Given that your quilt should be good to 32°F, I think mid 20's are a safe bet. I can't say how much warmth a VBL offers since I don't take temperature measurements, but the effect is significant. Much more so than wearing a thick down vest, and more than a down jacket at the end of the night.

[Jerry Adams]

If you have VBL liner, then you can't wear insulated jacket or vest inside because it will get wet

VBL liner will add a little warmth, but nowhere near what an insulated jacket or vest will

[Tom Lyons]

It is possible to get VBL clothing items that can go under your down jacket and down pants if you want to do that.
If you buy the stuff from the pro-makers of VBL clothing, it's going to cost a pretty large amount of money. The VBL sacks are much more affordable, and lighter.

An effective VBL that is properly operated by the wearer can give maybe 10-15 degrees more warmth than without the VBL. But this is anecdotal and variable, and must be tested by the user to see what they really can get out of it in the real world, with their gear set-up. Try it under controlled conditions where you can add warm insulation to your situation if the VBL is not giving the expected results.
Have a thermometer and some insulation layers available during the testing, so you can record what is happening at various temps, and this will become your reference data for future use.

The general benefits are that the down insulation retains all its loft, and is not degraded by body-generated moisture penetrating the insulation layer.
There is essentially no evaporative cooling happening at the skin level once the humid micro-climate is established inside the VBL, so you feel warm.
You have to be good at venting and layering, in order to properly operate a VBL.
If you are sweating in it, you are not operating it properly. But, it will have some moisture/humidity in it as part of its normal behavior. The baselayer inside the VBL is to keep the system from feeling "clammy" on your body. The insulation layers outside the VBL are used to maintain the neutral comfort temp. You must strive to maintain a neutral comfort temperature which is warm enough, yet not sweaty. It takes some practice, because it's typically warmer when you go to bed, than it is in the pre-dawn hours, and adjusting insulation is critical to maintaining this neutral comfort temp.

When you get up in the morning, it's going to be moist inside your VBL. This is normal, because that is part of what makes it work.
So, you should slowly vent it from the hood or openings, to allow some moisture to escape as humidity out the openings, without letting a huge blast of cold air in all at once. It will be quite chilly if you just expose your moist body and baselayer to cold air in the morning. So, vent some humidity off gradually, before getting out of bed. There will still be some moisture in there, but try to minimize it. I towel off right away, and get some wicking layers on over the top of me.

[Jerry Adams]

Classic way to try VBL – garbage sack – hole for head and arms – next to skin or outside a base layer – weighs very little so it doesn't have to increase your warmth very much to justify it – a lot of perspiration comes off your torso

[chris Mcfarland]

Thanks for all the comments and sugestions. I have a sol e bivy that i was going to use, but maybe I'll sew up a garbage sack suit so i can wear my jacket incase it doesn't provide the warmth i want. I'll bring a thermometer and journal my observations. I think if i have clothing layers it will be eaiser to vent than a bivy. Ill be testing this out on the 22-23 in the alpine lakes area. The only issue i see with this system is that i will look like I'm time traveling… my tyvec rain gear in combination with my trashbag suit will make it hard not to desperatly ask other hikers what year it is as I pass. :)

[Kevin Babione]

I was going through my closet this weekend and noticed the dry cleaning bags on some of my wife's longer dresses. They weren't made of the "Glad-Wrap" type plastic that is usually used for my shirts – they were actually a notch heavier.

They also looked to be about the size of a sleeping bag – certainly longer than 6 feet. If you can't find one in your closet to try you could probably pick one up from your local cleaners for nothing. It would be longer than a trash bag and could cover you from the neck down.

[chris Mcfarland]

That is a good idea… also because my wife died laughing at me when i showed her my white vbl suit… fashion has no place in my pack. :) i took a look in my closet an found just what you were talking about. My trash suit weighs 4.5 oz. Maybe i can shave a few grams with vbl v2.

[Pete Staehling]

A light coated nylon rain suit seems like it would work as a VBL. Comments on that? What if it was DWR, would that make it useless as a VBL?

People say that wearing clothing inside a VBL doesn't work. Is that true for base layers or thin pile that are less affected by being wet than down?

I have always thought I might use my rain suit as a last resort VBL, but have never needed to, so haven't tried it. I have managed to stretch my Mountain Hardware Phantom 45's range to 18F by wearing some fairly light clothing, very thick socks, and a silk liner inside a bivy. I figured the next step would be a vapor barrier.

[drowning in spam]

DWR serves to help water slide off the garment, which is especially important when the garment is not waterproof. Usually if a garment has a DWR, it's not waterproof. There are exceptions with multilayer fabrics though. The outer layer may absorb water even though that water can't pass through the inner waterproof layer. A DWR is sometimes applied to the outer layer to prevent it from absorbing water, which reduces water weight gain and allows the garment to dry faster. A VBL is inherently waterproof. It's also air proof, which it needs to be because water vapor is air. There's no reason a VBL can't have a DWR treatment too, but it won't make the VBL any more waterproof.

The problem with wearing clothing inside a VBL is that it absorbs moisture. If you take off the VBL, you're going to have more moisture to have to eliminate, and may result in getting very cold. I don't like having a VBL directly against my skin, so I wear as little as it takes to get comfortable.

You mentioned a light nylon suit. Anti Gravity Gear makes a sil nylon rain suit that doubles as a VBL suit. They'll also make it in a slimmer style and slight changes to work better as a VBL. I have one, but never used it. On one trip I got buy with a trash bag VBL. My legs went into a trash bag and had nothing more than boxer briefs. My torso had another bag, and I wore a vest over the bag. Not only did I stay warm that night, but my vest and quilt were drier (more loft) than they had been in days.

[drowning in spam]

Bumping to make this thread visible again after the spam attack.

[chris Mcfarland]

Update: i wasn't able to test as low a i wanted,but my trashbag suit kept me warm down to 27f with my setup… if it got colder i didn't notice because I was asleep :)

[drowning in spam]

That sounds like a great results Chris! Did you wear any extra insulation, like a vest, over your torso?

The great thing about a trash bag VBL suit is you don't have to make it until you need it, so you just have a pack liner and a spare pack liner until you need a VBL suit. One of those bags can even be used as a pad inflator, giving it yet another purpose.

[drowning in spam]

uninvisibility bump

[chris Mcfarland]

I premade my suit so i could layer my cloths on top. To enable venting i made footie bibs and a jacket I used some permaloft socks and my daybreak hooded on top. Cap1 andthin wool under. It took about 30min to vent myself dry in the morning, which got coffee an breakfast done. I'm calling this a sucess for cheapness but not lightness. The five oz i caried for my vbl could have been beter spent on more down… my only caveot would be wet weather tarping where a vbl would allow a fully wp bivy. Hummm

[Mary D]

My understanding is that the VBL is not so much for added warmth but to keep the moisture from your body out of the sleeping bag insulation when it's freezing or below. In those low temperatures, your body heat is not sufficient to push your body moisture all the way out. The moisture from your body tends to condense and freeze on the inside of the cold outer shell of the sleeping bag. In other words, a VBL won't do that much for you the first night out, but if you're out for several nights, it can make considerable difference to your sleeping bag insulation.

I have a silnylon rain suit which I use as rain gear. My personal experience with WPB fabrics is that I get just as wet inside them as I do with non-breathable fabrics, so why spend the $$$ for the latter? That way my rain gear doubles as a VBL. I wear it over only my Capilene base layer. If I need more insulation, such as my puffy jacket, it goes over the rain suit. Anything inside the VBL is going to get damp if not wet.

From what others tell me, everyone seems to react differently to a VBL. For me, above freezing it's a sauna inside, but below freezing it's quite comfortable. Others may need lower temps before they are comfortable.

[Kevin @ Seek Outside]

I have an enlightened quilt 20 degree. When temps dip to low, I use a lightly insulated bivy to get another 15 – 20 degrees. The insulated bivy also helps move moisture from the down to the outside synthetic layer

[Steven McAllister]

I know a few people who do as Mary does when camping below freezing. Silnylon rain suit under down clothing when sleeping.

The biggest complaint people have is changing out of the VBL inner to get into your hiking clothes at below freezing temps. It doesn't stop them though.
They say it really is a must for extended below freezing hikes. Keeps your down gear from loosing loft.

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