down compressibility

[Paul Tree]

I am planning on making a down inner quilt to increase the range of my synthetic bag and to use on its own for summer.

My question is should I still use 800+ fill or would a lower-number fill be just as good because of greater relative crush-resistance (resisting the crushing effect of the synthetic bag from above because it is less foofy) ?

[Vick Hines]

Paul,
Loft means loft. 800 fill takes up more space than lesser-volume grades. Don’t be fooled by talk about feathers having more resistance to crushing – something some manufacturers used to claim, so you still hear it now and then. It is not true.

Lower count down is lower because it has more feathers. Good down has practically none. Feathers poke through the shell of a bag – or any other garment. That means you have to have a *heavier* so-called down-proof shell. What that really means is *feather proof* or *quill proof*. 800+ down has few quills to poke through so you can use very light weight shells. I typically use 0.8 ox/yd for the inside and 1.1 for the outside of quilts when using 800+ down. Bill Forsnell has used 0.6 or less silk with good results. There will still be a quill or two, but not enough to matter.

FYI: Properly speaking, down consists of plumaceous barbels with no central quill or shaft whatsoever. The barbels radiate excentrically from a central point and the barbels are not straight.

A feather has a central quill (the part that goes in the bird), a shaft (the extension of the quill), two vanes set 180 degrees apart, consisting of parallel barbs held together by regular barbules. The fuzzy stuff on the bottom of the feather is plumaceous barbules. It looks downy, but it is not down. Then there are *pin feathers* which have a quill, some vane and some plumaceous barbules. And finally there are *plumes* which have a quill, a rudimentary shaft, plumaceous barbules but no vane. Some folks like to claim that plumes and pin feathers are down. They are not, but poor quality down will contain them.

The technology for mechanically separating down from feathers, pin feathers and plumes has improved dramatically in recent years, and accounts for the greater availability of high count down. Thirty years ago the separation was done by hand. Incidentally, one such process, air column grading, was invented by our old impractical philosopher friend, Henry David Thoreau, over 150 years ago. But only recently has it been applied to down.

[Paul Tree]

thanks for the info, I’m glad to go with a better material.

[Johnathan White]

Please correct me if I am wrong but, won’t having a down inner quilt be compressed wihtin the sleeping bag, negating the porpose of the extra loft?

[Paul Tree]

yeah, it will somewhat, that’s why my question. I just need to bump up my bag’s rating a bit. If it’s cold and dry, it could be used on the outside. A flat quilt sounded easy to sew.

[Johnathan White]

Ahh. I read through your first post and now feel stupid. I have also been looking at some kind of liner setup since my 0 degree down bag will in no way fit into my UL pack.

Johnathan

[Frank Deland]

Why not just lay the quilt over your bag maybe use some thin webbing or elastic webbing to hold it in place. Warmlite uses a zipper system to hold the lighter weights ontop, rather than stufffing any layers inside. In short laying the quilt ontop would not compress the down of your bag that much. What a great explanation of the down, too. Thanks. If down does poke through your bag, pull it back in.

[al b]

Why do insulation companies not make a polyester copy of downs structure to gain weight to loft and compressibilty with more insulation when wet?

[Peter McDonough]

For the same reason NASA doesn’t just superglue the foam to its space shuttle and we don’t make a medicine that targets and kills all cancer cells or cures the common cold.

Its just not that easy.

[Richard Nisley]

Three insulation products are polyester synthetic down copies. They are Primaloft One, Primaloft Sport, and Exceloft.

[Brett .]

Vick, it is obvious you know a lot about down, and maybe are simplifying it a bit for us; “Lower count down is lower because it has more feathers”. As you explain later, down is fundamentaly different from the plumaceous feathers. Here in Japan there is a requirement to label the % ratio content; for example a jacket might say 75%down and 25% “small feathers”; so shoppers can be aware what they get. I have read there is more to the quality of down than just the % contamination with feathers.. old ducks, cold weather ducks, geese, oily residue etc.. can you (or anyone) explain more about what makes good down? Sure, I am researching it on google, but I appreciate any first-hand knowledge. I recently began replacing my plastic-type clothing and sleeping bags with natural materials such as down, wool, and silk. Thanks in advance.

[Frank Deland]

Just to jump in before Vick answers more completely. I believe in US, a “down” product has to have at least 30% down. Down has no quills or spine. An 800 fill product should have far more down that feathers with quills. For example, if you look inside a standard “down” pillow, you would find a lot more feathers with quills than you should find in a 800 fil sleeping bag. I have used 800 fil down in homemade products(sleeping bag and quilts), it is almost all fluffy down, ie. very few feathers with quills. For a random guess, I’ld say 85-90% down.

[al b]

Whats so difficult about making ‘pom-poms’ (like the baubles on woolly hats) out of wavy fine polyester/polypropalene/alkenes instead of wool?

Wouldnt this essentially be synthetic down.

Primaloft sounds like another Hollofil to me: cut staple presumable means its lots of small fibres glued together so wont last as long as continous wadding (Polarguard) or proper synthetic down as suggested above (or real down).

[Richard Nisley]

The key design elements of synthetic down are to match the excellent insulation characteristics of goose down but not allow the insulation to degrade when wet.

Primaloft One most closely matches goose down. It does this by: 1) two polyester fiber sizes mixed together in an approximate 80% fine / 20% thick ratio; 2) fine fibers are 2 micron or slightly larger whereas the thick fibers are at least 10x larger; 3) the fine fibers are cut and thermally crimped to the thicker fiber in the same proportions as goose down and 4) all fibers are then covered with silicon to waterproof them. It should be apparent that it is much more complicated and expensive process than the synthetic pom-pom or continuous fiber techniques. Two other synthetic insulations are based on the concept of synthetic down but are not as effective as Primaloft One. Exceloft uses the two fiber dimensions and mixes them together without crimping and cutting. Primaloft Sport uses a thicker fine fiber dimension to increase durability.

Primaloft One is about 39% more thermally efficient, for the same thickness, as Polarguard Delta. As a result of its silicone coating it will retain almost all of its insulation value when saturated in water as apposed to only about 60% for Polarguard Delta and 40% for goose down.

On the flip side, as you correctly pointed out, Polarguard Delta is more durable. This is because it doesn’t have the fine fibers which can degrade with compression. Although you didn’t point out cost, that is also a factor. Polarguard Delta insulation is less expensive because the manufacturing process and materials are less costly. The end-user products made from it are less expensive because you don’t have to stabilize the insulation as much and it can be laminated to face fabrics. Polarguard Delta is not coated in silicone like Primaloft One is.

I personally own goose down, Polarguard Delta, and Primaloft One products. Understanding the benefits and shortfalls of each, I select the appropriate one for my intended application.

I suspect that making synthetic pom-poms would not be difficult. The issue would probably be the competitive insulation characteristics. The high pom-pom density at its center and the air gaps between the individual pom-poms would theoretically result in poor insulation performance.

[ROBERT TANGEN]

Is down from the Eider duck more efficient than down from geese? Why? Would it pay to raise Eider ducks as a hobby?

[Brett .]

Richard, thanks, that was an excellent post; I copied it to my ‘file of gear knowledge.doc’

[Richard Nisley]

Eider down locks together so that baffles aren’t required like goose down garments and bags. The resultant product is lighter as a result of this. 800+ goose down is near the theoretical limit of what can be achieved with air based insulation and so Eider would only be marginally better. I don’t believe that you could perceive the difference in warmth but you could tell a difference in weight.

If you live someplace very cold I am sure that you could sell as much Eider as you could gather to “BPL do it yourselfers”. There may be one little problem…an Eider quilt typically retails for about $4k.

[david chan]

Interesting though Richard’s and Vick’s answers have been, I think it is time for an authoritative technical explanation of down filling. See http://www.facewest.co.uk/pp/trek/fillpower2.htm

[Roger Caffin]

For a good start on understanding down, trawl through the web site of the International Down and feather Laboratories at http://www.idfl.com

Eider ducks are wild birds living in very cold regions. They do produce the best down, but very little of it per bird – very little. It is hand-collected from the nests at the end of the season. Home farming? I doubt it would work – unless you did it above the Arctic Circle.

[paul johnson]

Roger (or Richard), just curious; maybe you know the answer. The ducks live in such a cold environment. Why do they produce such little quantity of down per bird. Are they tiny ducks? Do they retain it due to the cold temps not letting up to a great degree, and so molt little?

[al b]

That is very interesting:—

My idea was that the pom-poms would be more than one layer so the gaps would be plugged by other (loose) pom-poms, (eg like stacked oranges).
Also, perhaps the poms-poms could be eliptical.
Would silicon coating(or similar) down clusters work?

I thought down lasted a long time because the clusters are loose, so cannot be ripped like wadding, hence it made sense for synthetics to copy this:

I shall re-make my other suggestion of placing a rip-stop grid through synthetic wadding to allow it to be robust without quilting to an outer shell.

[David Olsen]

Eider down is harvested from the nests.
Goose down is harvested from the bird
after slaugher. And geese are bigger.

[paul johnson]

Mr. Olsen, Understood. Thanks for the explanation.

[Dylan Skola]

For a while at least Nunatak was offering Eider down fill on their items . . . for $125 / oz. Check the May 2005 section of their announcements.

[Vick Hines]

1) Eider ducks are very rare and highly endangered.
2) The only way to get their down, other than killing them, is to raid their nests, preferably after the chicks have flown.
3) If you could get the down, you would find it amazing. At one time, the US military had a lock on all Eider down, and used it for special missions gear. I don’t know the current status with that. Ooops. Dylan answered it.

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