MYOG down jacket baffles

[Sarah Pigeon]

I am making a down jacket. If i make sewn through baffles with about 4.5 oz of down fill it’s loft will be about 1.5-1.75″. If i make one with box construction baffles with the same down fill it will have a loft of about 1″. Which jacket would be warmer. Both have the same amount of down fill. The sewn through has a higher loft, but the box construction baffles won’t have cold spots. Any words of wisdom would be greatly appreciated. Thank you!

[Richard Nisley]

If you wear a properly sized shell over the sewn-through, it will be the same warmth as the baffled but the baffled will have a negligible increase in warmth. This phenomenon holds up to about 6 oz of fill.

If used without a shell, the baffled will be warmer.

[James Marco]

Yeah, pretty much agree. Baffles don’t work all that well on light jackets/hoodies. In colder weather, I often layer them differently depending on the temp. Under a rain jacket/wind shirt or under a light fleece they can be warm. Over a light fleece they are less warm and over a base layer, less warm than that. So, a simple rearrangement of your insulating layers can effect your comfort range by a good 10-15F. (Of course this leaves out zipping, pulling sleeves up, etc.)

[Sam Farrington]

Can you wise folks explain to us why baffles work so much better with the box construction and the garment uncovered, and not so much with a shell?
Maybe it has to do with the compression from the shell collapsing sewn through construction so the down pockets are squeezed together?
Also, if going to the trouble of box baffling a jacket, isn’t it likely the wearer would be planning on wearing it without a shell to improve ventilation with less heat loss?

I have some old box baffled jackets, both down and synthetic, and they’ve always been super warm, although don’t see anything like them around these days. With the winter we’ve just been having, maybe it’s time for some box baffles.
Just wondering.

[Roger Caffin]

Box baffles are rather expensive to sew. The current trend is for cheap, cheap, cheap. Heading to the bottom of the barrel.

Cheers

[Richard Nisley]

Sam,

A Shell over sewn through seams (<~6 oz fill) creates optimal sized dead air spaces. This largely negates convection, conduction, and radiation losses in the seams area; thus  providing equivalent warmth to the more expensive and heavier box baffled construction.

 

 

[James Marco]

Richard, +1.

Note that in some cases, a light sewn-thru  jacket under a rain jacket can actually be warmer for the weight than a box-baffled jacket. The air-spaces are larger than what can be accounted for by down-loft in the majority of the down jacket. Only the shoulders suffer from loft loss due to the weight of the shell. I think Ryan noted this “trapped air-insulation” effect in his article on fishnet long-johns, too.

An article on baffling written years ago by Jack Stephenson outlined possible baffling shapes, especially for lightly filled box-baffles. He hypothesized that trapezoidal baffles would work better, but I am not really fond of that for bags. It showed some drawings where there would be some weight advantage to this arrangement by avoiding small unfilled/uninsulated gaps at the top of each baffle in a jacket due to down settling. I think the offsets in warmth/weight  (slightly more material used for the trapezoidal baffles vs the better fill coverage) likely negate each other. A slight amount of overfill will work better at the same weight for less assembly work. Anyway, just a thought…

[James Marco]

Sam, most of us Lightweight/UL people usually travel with the lightest gear possible. For myself, that means my gear tends to be as versatile as possible in 20F and above conditions. I tend to think in systems. Dual purpose is a tenant to as much as is feasible.

For insulating hiking gear, I usually bring a 12oz sewn-through down jacket, a rain jacket (or shell,) my hiking shirt (a synthetic base layer,) a light fleece (120wt.) I use my jacket over my shirt/fleece, and my rain jacket over that. Often, I don’t need everything, and can slip off a layer or two…no big deal to loose heat. I know you understand this, Sam. But, there are others that may not.

For box baffles, I have found that they work really well for quits and bags. But for jackets, not so much, unless you are talking conditions when every Watt of heat counts (as Richard mentioned indirectly in his limit.) As I mentioned, and as Richard has said, a shell over a sewn-through jacket works as well (I would add slightly better.) While the total weight is probably higher, rain shell + jacket, it also allows me to use either alone and for other purposes allowing me to carry less total weight.

[Sarah Pigeon]

Thanks everyone for your responses. Making a jacket with sewn through baffles makes life so much easier; although I may consider making a fully baffled jacket later for mountaineering. One step at a time though.

[R]

As the R value depends on trapped air volume (or convection cell size), the baffle size should play a role there. In a sewn through jacket, it’s about more than just fill volume and loft.

Can anyone offer any insight on this?

Or are typical dimensions to accommodate the loft you get with the fill weight range in question all good enough?

[James Marco]

Rene, I don’t believe there is a set formula for this. Square, tubular, V shaped, diamond, curved, etc are all used in various models. Roughly, a 2″ baffle should leave about a 1″ center baffle height. But this can depend on a lot of other things, too.

Fill of the down you are using. For example, some people like to use very high fill power down (around 900 or 950.) The weight of an outer shell can mean the shoulder region will compress more loosing some loft. so you could end up being colder with 950fp down than with say 850fp down under windbreaker or rain jacket. Dampness would have more effect on higher fill power down, also. Going with a 500fp down might leave you colder if you use this as insulation at night though under a rain shell in damp air it works better than 950.

Anyway, fill power, your average use, closeness of seam to center, tightness of the fabric between seams, ie, how many puckers you allow, amount of down you use can all effect the loft between baffling. A slight differential cut is likely wanted to avoid compression as you zip up a jacket.

 

[R]

On a slightly different topic, but still relevant to the OP’s interest, has anyone tried the hybrid insulation sewn-through approach?

Rather than trapping the down between two layers of shell fabric, one side is synthetic insulation.  Then finish the garment with the other shell layer.  The synthetic insulation goes on the side away from your body, to trap condensation (better in synthetic than down), and the outer shell layer isn’t perforated with baffle stitches.

It’s a touch heavier than pure down but fares better in wet, humid conditions.

[R]

Thanks for the explanation, James.  In a hybrid, full synthetic over the shoulders could be good.

[Sam Farrington]

While I think that box baffles are clearly superior for down bags and quilts, the OP is looking for guidance with jackets. She also mentions she will be sewing. So I will stick to jackets.

My understanding is that the size of air pockets in insulation is critical to heat retention. Hence, some of the best synthetic insulations use a combination of heavier and stiffer fibers to maintain loft, and lighter fibers that create much smaller air pockets to retain heat. Down varies greatly in quality, but with high fill power, is generally believed to provide better warmth for weight.

Hence, I think that for a down jacket that will usually be worn in fair weather, and without a shell, box baffles are the best choice for down, because the jacket will ventilate better, provide more warmth for weight, and a quality DWR treatment will repel precipitation if caught in the wet for brief period. Such is the case with my brother, whose outdoor activity is walking and day hiking with big fluffy dogs, and the best quality down jackets are all he wears. Why doesn’t he use box baffles? Because few if any are marketed. If you want one, MYOG may be the only option. Some will say few are marketed because they are expensive to make, are not essential for comfort and light weight, and there is no demand for them, which appears to be the consensus here. Nevertheless, some makers struggle to create jackets that do not make the wearer look like the Michelin man, and my old box baffled synthetic jackets do a great job at that.

For backpacking, especially in areas where precipitation can be lengthy and intense, like New England or even northern Colorado in recent years, IMO synthetic insulation is better. I still have the latter day Polarguard top and bottom that were sold on BPL in its early days. They are stored loose and only compressed when in a pack, and contrary to popular opinion, have not lost any loft. They weigh a total of around one pound for both, and are used mostly in the tent or shelter; but when caught in the rain around camp, they do not become saturated in the brief time it takes to move to cover. A grid fleece top is also carried, is very light as well, and is worn under WPB raingear when 3-season hiking, or just to take the chill off in fair weather. I don’t backpack in the winter, so leave that subject to the more intrepid. The only down I carry is in a Montbell spiral down bag, has a super DWR treatment, and never gets wet; although that also involves use of tents that don’t condense, which is a matter for another thread.

[James Marco]

Rene, yes. Some manufacturers have done that. Some actually mix the two, synthetic and natural down in some jackets.

https://www.outdoorresearch.com/blog/article/down-vs.-synthetic-whats-the-difference-between-down-and-synthetic-insulati

https://www.rei.com/blog/camp/down-vs-synthetic-which-insulation-is-right-for-you

https://www.backcountry.com/Store/catalog/search.jsp?q=hybrid+insulated+jackets&s=u

[James Marco]

“My understanding is that the size of air pockets in insulation is critical to heat retention.”
Well, yes. This is true as far as it goes. Smaller air pockets are better for insulation value than larger air pockets. As an extreme example, a few companies out there (Klymit) released a vest that was simply inflated (they suggested helium, as I remember, and had special cartridges you could buy.) This never had very good reviews. Other companies had other means of decreasing the amount of down used for insulation.

About 50 years ago, I had an old Korean War coat (arctic gear) with down in sealed plastic sleeves. Warm as anything out there but also heavy. It is really not about just warmth, it is the combination of warmth and light weight. For all we do with synthetics, down still has the best combination of weight, insulating value and durability on the planet. Just like spider silk is considered the holy grail for fabrics and rope. Spectra is stronger, but abraides easier. It doesn’t have the natural toughness.

Down breaks down from a central core to many fibers. Each fiber has thousands of smaller “barbettes” on them. This is what gives down the high insulating values. A synthetic can be seen as a single fiber without the barbettes. The small barbettes (I don’t remember if that is the correct name) trap very small air pockets (they have small hooks on them allowing them to cling together.) Even fairly compressed down (say 10:1) will retain about 50% of its warmth. Compressed synthetcs are just cold. That said, if the small air pockets are replaced with water, there is no real value to down. For synthetics, the stiffness means you will have a little. Sometimes, as in jackets, this is useful. Sometimes, not so much. Sleeping in a mud puddle at 35F is still going to be a very cold experience so keeping synthetiscs dry is important, regardless of it’s ability to retain some insulating value when wet. (The fibers themselves are usually hollow.)

https://www.outdoors.org/articles/amc-outdoors/the-incredible-structure-of-goose-down
https://www.google.com/search?q=microscopic+holofill&tbm=isch&source=univ&client=firefox-b-1-d&sa=X&ved=2ahUKEwjv96PjvvzgAhVONd8KHcBFCF4QsAR6BAgGEAE&biw=1527&bih=927#imgdii=b5OvqUwiaerk8M:&imgrc=Khs6x5Esst4yLM:

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