Durability of different fill-power down

Can anybody tell me if there are documented differences in how long different fill-power downs will retain their original loft?

Based on really limited observations, I would have to say that the lower fill power downs (eg. 500-600) appear to be more durable than the more expensive, higher fill-power downs. This is based on experience with older and heavier down gear and comparing it with newer high-fill, lightweight gear.

As an example, I have a circa 1972, REI down sweater that was probably originally made with 500 to 600-fill down. As best as I can discern, this garment has lost relatively little loft in the 35 years I have owned it. I also have a circa 1956, Eddie Bauer down bag filled with feathery down that, while pretty skanky, has nearly it's original loft. Both of the older pieces of gear have had a lot of use. In contrast, I have a quilt I made using 800-fill down that seems to have noticeably lost loft over four years of gentle, careful use. The same observation applies to an 800-fill down jacket that I made.

I concede that the above is not a rigorous test of any hypothesis but it seems to be a legitimate question. Moreover, I think I could make a theoretical case that the cheaper down, while heavier, could also be more robust.

Would anybody with experience in this care to comment?

Maybe the difference is in the maintenance that is required.

For example, maybe the older down garments/equipment suffered less loft degradation due to body oils/sweat. Therefore, you never laundered them.

I bought a department store down quilt several years ago for $40 on sale. After two or three years of use of over 100 nights per year (200 to 300 nights total), the loft was considerably less. I washed it with down specific soap and dried it in a commercial large dryer following instructions for high quality down gear. The loft gain was astonishing.

I used it for two more years, and then became bored with it. So, I bought a new one (on end of year sale) with 550 cu. in. per oz. claimed fill.

I have a 700+ down fill bag that suffered from loft loss and smell pickup from a hot summer on the Appalachian Trail. That laundered up real well. In fact, I used the down quilt as practice before I did the bag.

There is a higher feather content in the typical lower loft "down" products. Feathers are expected to degrade in loft differently than the fluffier down clusters that dominate in the high loft "down" products.

It is common to claim that the traditional backpacking products were made "bombproof" while the new lighter weight products require more care and careful handling as part of the tradeoff between performance and weight.

More care?

While I totally do not have an answer to the durability, I have restored loft to some pieces by washing and fluffing them.

I swear by Atsko Sport-Wash since testing it for BGT some years ago.

CM

I have a quilt I made using 800-fill down that seems to have noticeably lost loft over four years of gentle, careful use. The same observation applies to an 800-fill down jacket that I made.

Could it be construction tecniqes? Of all the things that I've made,(although they work o.k.), they seem to lack the quality of most manufactued goods. Even the cheap stuff.If I had more $$ I would buy all my gear. Even from other DIYers. Then I could blame them for defects.

I seriously doubt it. I have made other items with the lower fill-rating down and have not had this problem. Moreover, I use pretty much the same techniques as do the manufacturers. So, I don't think this is the issue.

Well, I haven’t noticed this problem.
I have a 1977 550proof down sleeping bag (0F rated) that still lofts very well. It has been washed once.

None of my WM 850proof bags have lost loft and they have seen a few hundred nights in them with my family since 2003.

In 2004 I bought a WM Flight Jacket (850proof). I wear that jacket about every single day for 6 months of the year because of global cooling . So that jacket has seen 900+ days and it still looks new and fluffed. It has been washed once. I dry it out by riding my little Honda scooter at 70mph. Talk about fluffing it up! It handles 20-50F weather very nice.

I have a JRB Stealth 800proof quilt. I’ve been only using that for the last 8 months. It still looks good but the jury is still out on that.

And this place http://www.idfl.com/articles/Fill%20Power/IDFL%20Fill%20Power%20Questions%20and%20Answers.pdf can return a 5 year old bag in cold compressed storage to its original loft!

I’m just wondering if the down you have somehow lost its natural oils…

-Barry

Barry
As you point out, the WM products seem to stand up. This IS construction technique AND a quality company that probably simply puts more of the down in their products.

In my own humble opinion, 900 down that lofts at its max to say 100 cubic inches and 650 down that lofts to the same 100 cubic inches has very different material in it. That 900 loft is probably optimistic and is like testing stoves in the warmth of your kitchen vs in a cold wind. Where 900 may be "better", what does better really mean? Maybe you have to treat 900 down as though it were 800. If you only use a tiny amount of down because you "Believe" what you hear, then you may be fooling yourself.

As I have stated I would rather have a 700 down sleeping bag than a 900 down sleeping bag because the 900 is going to collapse under any weight of pressure BECAUSE IT IS SO CAOLAPSEABLE/EXPANDABLE. Its like fleece for example, it doesn't compress much, therefore it also doesn't lose its loft. I think the extreme desire for hyperlight items is clouding the reality as reported by observation.

Just my $.03 worth
Jim

Phil gibson,and associates , at Natick Labs published work on the thermal conductivity of down and some synthetic insulations as a function of compression.
www.jeffjournal.org/papers/Volume2/Gibson.pdf

As the down is compressed to higher densities, the thermal conductivity declines (thermal resistance increases) which can be seen from the figures.

This paper does a poor job of describing the materials used. It appears as if the down used was 550 fill power based on the lowest down density listed in the figures. No, the authors never specified the down quality.

Some "down experts" have argued that when you design a garment with 800 Cu.In./Oz down, commercial experience is to overfill the down chambers slightly to give them a little "Puff" feel.

Any overfill makes them slightly less (very slightly) compressible but the loss of thickness from compression is made up partly by lower thermal conductivity of the compressed down.

So far, almost all of the papers I have read on down are full of vague spots, such as not telling you what down is being studied as in the above example. Sometimes, as in the above paper, you will find descriptive claims that are marginally correct. You cn find "down experts" who leave you more confused than you were before you talked with them.

“As I have stated I would rather have a 700 down sleeping bag than a 900 down sleeping bag because the 900 is going to collapse under any weight of pressure BECAUSE IT IS SO CAOLAPSEABLE/EXPANDABLE.”

It seems any down is collapsible. If you want to make it more firm, just stuff more down in—which also makes it more warm. For a sleeping bag, the down is on top; thus a tough LIGHTWEIGHT material shell won’t collapse it. It will poof up faster.


“Where 900 may be "better", what does better really mean?”

It should mean higher quality and be warmer for the same weight of 700 down (w/o overstuffing volume). I think TomD noted this sight a while back: http://www.downandfeathercompany.com/categories/How-to-Choose/How-to-Choose-Fill-Power.aspx I like it’s pics of comparisons and ‘fill power facts’.

-Barry

True down consists of plumules with no quill whatsoever. High fill down has fewer quills than low fill down. Compression does two things to low fill down; it kinks the quills so they provide less loft and it pushes quills through the shell which can result in loss of loft. Anyway, I have gotten much more use out of high-loft down items than low-loft items.

Here are some other considerations:
Oxygen and ozone both attack down, making it brittle and less able to fill space. Cleaning fluids and electrical appliances, among other things, can create ozone. Moths love down, too. So be careful where and how you store down items.

Waterfowl down has natural water repellant oils which is removed by detergents and even mild soap. The safest way to clean a sleeping bag is to wipe the shell with a cloth moistened with rubbing alcohol. I don't ever wash down sleeping bags or quilts.

The safest storage for down bags and quilts is to use them on your bed of as throws. A simple duvet will help keep them clean. They sould never be stored compressed. A loose, large, moth-proof bag is the next best choice after the duvet.

For reference, I have two old Frostline down items I made 35 years ago. One is a Cougar sleeping bag, the other a simple vest. Both items received the same down fill (no quills). The bag has only been washed once since I used it with a silken liner and appears to have its original loft (yes it smells a bit weird right now). On the other hand the vest has maybe a third of its loft and has gone through many machine wash cycles with general laundry detergent. I would guess that the agitator of the wash machine is what killed the vest, probably ripping the down filaments when they were wet.

I'm into lightweight, so like the highest loft down available —800-900 down. Alternatively, this attitude makes no sense at all when you consider that I'm more than a little overweight, and so losing weight will have far more effect than lightening my gear. However, I can afford lightweight gear, but haven't been able to discipline myself to the point where I can get my weight back to where it used to be. (My birthday is today—I'm 58.)

Anyway, lots of opinions on this subject of down loft and fill power. The science on this subject seems to be sorely lacking.

Dragon,
There IS no science on down fill power, just regulatory standards which were relaxed under the Bush administration. Therefore, 900 cubic inch down is 2005's 800 cubin inch down.

Fill power is measured by how much space a precisely weighed sample of down will take up when it has a certain weight on top. Under the old standard, the down was compressed under the weight (a piston) and released. Its fill power was whatever volume the down returned to. This gives a realistic picture of how a down garment will loft when removed from a stuff sack. Under the Bush standards, the weight is placed on the down and allowed to settle. There is no compression step. The level to which the weight settles is taken as the fill power. Obviously, this gives a higher value - which is just what some big manufacturers wanted.

Down testing is supposed to be done by independent labs. It is supposed to be done scientifically. The tests are supposed to be consistent. If all criteria are met, you can compare different down regardless of what test is used. However, if you design a garment to hold X oz. of 900 cubic inch down, it will be underfilled. If you calculate your volume based to 800 cubic inches per ounce, you ought to have the right fill.

About personal weight. It is still better to go as light as possible because you will travel faster and farther - but, and this is important, you will burn more calories by doing so. This is true with both bicycling and backpacking - and it has been tested in competitive cycling. So, get your pack weight as low as possible. You will lose weight while having a better backpacking experience.

Spock
"There IS no science on down fill power, just regulatory standards which were relaxed under the Bush administration. Therefore, 900 cubic inch down is 2005's 800 cubin inch down."
********************************************
cool, so then my 1988 700 down must be 1200 by now, excellent.
Jim

Jimshaw,
Don't push it. Before about 1970 it was all guesswork. That old 1988 bag's down is probably moth poop by now.

I still use a Holubar down double bag from 1962 - not routinely, but regularly. If it has turned to moth poop, the insulating value of MP must be roughly equivalent to down.

Spock
I have never stuffed or washed the WM super kodiak (or even gotten it wet, and I don't tink it has lost any of its loft. It was rated at 700 when new and it is actually a LOT nicer than the old 650, and I suspect that it is more like modern 750 or 800 as it was the highest quality available then and cost $500 in 1988.

We don't have moths in central Oregon, its desert.
Jim

Jim,
I don't think so. The topic is "Fill-Power". If you reflect on that terminology for a moment, it simply means that some down has more power to fill a space than other down. That's one reason I can tell a WM bag by feel in a rack of various makes of down bags-- the WM down "pushes back" at you. The other down feels like cottage cheese.

Perhaps think of it like the power of a metal spring: Will a spring of lighter weight with a given loading ability fail sooner than another spring with a lower loading specification and begin to "sag"? Not really. Only if its elastic limit is exceeded.

I interpret a higher fill-power rating to mean that the down is actually more robust rather than weaker. In fact, I would expect down of lower fill-power to "go limp" sooner because the material was more floppy to start with. I don't have enough experience to make a scientific conclusion, but that's consistent with what I have observed.

Just my $??.?? -- whatever you want to value it at. ;-)

Jimshaw and Ranger: Lucky you. My old Ski Hut mummy seems like it's stuffed with chicken feathers now. I would clean it out and replace that old down, but I suspect it would still be heavier than I now prefer.

I agree with not washing a down bag. They air out pretty well and a wipe down with rubbing alcohol will remove any intolerable dirt. After long continuous use my bags/quilts start smelling like warm puppies. Comforting.

Keith
I suspect that you are correct in your analysis. I have a WM bag and I understand what you are saying. Yes I agree the higher rated down should have more "springyness" as you describe. Why is it that that the WMbags can be easily identified by feel?

I think my prejudice is against the UL 900 down jackets with 4 ounces or less of down. My old 550 down jacket from REI has been around for 25 years and cost me $60. I think its about as lofty as when I got it. It doesn't compress a real lot while wearing it, I think because is has less compressible of down and probably a lot more down since it weighs 25 ounces.

I believe both of these two concepts to be real fact, how they relate to each other is a puzzlement. There seems to be a dichotomy - the higher rated down should be "springyer" yet it compresses more easily, or is that a misunderstanding? If we use the spring alanogy the 900 down would be longer weaker springs wouldn't it? F=Kx and all that. I'm not certain how "power of expansion" and "ease of compression" can be described in terms of pysics. Also the higher rated down has a higher content of "warm" stuff. My "700" down WM bag is drastically warmer, softer and more compressable than 650 down seemed at the time I bought it.

Jim

This is largely true. Here and there you can find some published papers on some more basic science aspects, but these are generally isolated and not a part of any unified effort.

One professor at UC Davis has published several papers with a series of graduate students. I have lost the link to his website and list of citations.

There is little visible benefit to the equipment making industry (sleeping bags, and garments) to invest in down science.

There are a number of people who are "experts" of the consultant sort who may write on some outdoor discussion boards. I have found that their writings often cause my brain to slowly fry. Not just because the writing style is blurred, but because the statements made often make no sense.

I remember one time, such an expert illustrated his point with some "established" data on down. He left enough information in the illustration from which one did track down the original source. The data was actually data on chicken feather/down mixtures, and was over 50 years old. He retracted the old data and substituted new data. I found that the original source for the new data was a paper published from Natick Laboratories (US Army) [the "new data" was unsourced].

I am no "expert" at down, and urge great caution in selecting sources of "qualified experts".

If you "overfill" a down chamber, the compression of overfilling increases the stiffness of the down chamber and it pushes back at you more than the same chamber filled with a "Normal" amount of down.

To use your spring analogy, F=-KX where K=spring stiffness and X = displacement. If you start with X=0, the feedback force from gently displacing the down is going to be about Zero (0). If you use cloth to compress the spring to X=1 and then you gently push on the precompressed spring, you find the feedback force to be about K, instead of nearly zero.

So, you say, "Whoa, I'm only going to precompress the spring (down) a liitle bit, say X=0.1" Then instead of nearly Zero for a resisting force you have 0.1K as a restoring force. And 0.1K is greater than 0.0K.

If you want to emphasize down pushback as a tactile sensation, then overfilling the down tubes a little is a good way to get it. Most folks will tell you that if you want to increase the warmth of a sleeping bag, overfilling is a good way to get it.

So, overfilling the down tubes gives 1) warmth and 2) nice pushback feel.

Rocket,
I like your analysis. If x = .1 then the down has a bit more pressure against the fabric to keep it from deforming under slight pressure, such as a rain shell or wind pressure. As an aside I have noticed that down insulators that flap in the wind lose a great deal of their warm and "indoor measured loft". When you say "normal" are you saying "at the maximum limit of expansion vs the available space inside the garment?" I think that's what you are saying and this is specifically my problem with ultralight garments and I'm not sure that "over-stuffing" enough to prevent deformation by slight pressure should be referred to as "overstuffed, but rather "correctly stuffed". I think the industry is playing too much on the numbers and peoples desire for minimum weight to want to do this, it also costs a bit more expensive down, but heaven forbid that they lose sales because their "improved loft" model weighs 1 ounce more.


One big difference between my Wm Kodiak and a Wm Puma which is rated far lower, is one vs two draft tubes. My back was decided cold when sleeping with my back against the zipper. I took the bag back to WM because I felt it didn't hit its rated value because of this and they put more down into the draft tube, a couple of ounces, enough to add a bit of weight, but also a lot of warmth.

As another aside, the bag is huge, designed for a 250 pound 6 foot 6 linebacker and I'm a little guy who likes to be able to stretch out in my sleeping bag, so I inserted 1/8" diameter elastic inside the bag just under the inner liner, above the knees and near my waist. The bag is a lot warmer because of this. It both isolates three area in the bag lowering any internal drafts to zero AND it bunches the bag up giving more loft, AND I can easily stretch in any direction and then the bag always snuggles up to me. This bag is rated at -5 and would be pretty comfortable at -5, but if I pull my big down coat over it, I am actually warm and toasty at -5. The bag has enough "resistance to compression from outside influence" that the coat does not cause its loft to suffer.
Jim

<quote>I think my prejudice is against the UL 900 down jackets with 4 ounces or less of down. My old 550 down jacket from REI has been around for 25 years and cost me $60. </quote>

There may be a number of factors going on here. I share your skepticism of some of the super-high fill ratings. I wonder if there is a certain amount of "specification creep" going on -- given that there is no official oversight (except now in europe for finished goods).

Well, I don't know if this is a testiment to lower fill down or the quality of the bag, but...

I've got a Marmot Osprey bag I bought back in the late 80s. Semi-rectangular, 30 degree rating,600 fill down, just under 3 lbs, with a couplet sheet that allows you to unzip the bag and use it as a comforter for a two person setup.

Put some crazy use on that bag for well over a decade. Then, bought a new bag and put the Marmot up in storage stuffed in its stuff sack. This past December, after about a decade of compressed storage, I took the bag down from storage and was figuring to sell it. Thought it would still do great as a sleep system for a couple.

Went to the laundromat, washed it and dried it with a few tennis balls thrown in to help break up the down clumps. Got home and finished unclumping and shifting the down. Finished up, zipped it up and layed it out on the bed. I swear that bag looks as good as new and hasn't lost a mm of loft.

Took the bag with me and used it for a trek to the Mojave National Preserve the first weekend of January, temps down to freezing. Slept ever so comfy with the lightest of base layers.

Now, I won't take the Marmot on the trail; I've got a much lighter 20oz 750 fill bag that does everything I need (and a lesser 20oz'r that works beautifully as an overbag). However, though I was planning on ditching the Marmot, thinking its best nights were behind it, that baby is staying with me and is at least going to be the new bag for base camp when I'm out on mountain biking getaways.

No moth poop here!

Still warm and lofty after all these years!

I bought what is essentially the same bag in 1983. I, too, have had similar experiences. Mine is still in use, although I usually carry lighter bags on backpacks. One, tough, durable, versatile bit of sleeping gear.

Can I get an "Amen"!

The Church of the Sacred Marmot

It's just a guess, but maybe it has to do with how densely they were stuffed to begin with. That is, if the older bags were stuffed "tighter," maybe any degradation would be less apparent. I suppose it's also possible that the newer down was processed more vigorously, perhaps to meet newer health standards (pure speculation). It could be time to wash the quilt, too, if it's never been done.

Fill power is based on an objective test using one oz. of down in a tube with a weight placed on top of it. I posted a link to a site with the testing procedure on it a long time ago; might still be here somewhere. Here is what's posted on Wikipedia-
http://en.wikipedia.org/wiki/Fill_power
There are links to a test lab at the bottom of the article-same one I linked to, I think.

The bottom line is that higher numbers mean more compressibility. How well an insulator works in a particular product will depend on construction. The idea is to create as much dead airspace between you and the outside air. A 650 jacket could be just as warm as an 800 jacket, just not a compressible and will weigh a bit more.

Tom D
I think whats changed is there is no "weighted piston" anymore, no weight given nor diameter of cylinder stated, not weight per square inch remarked. I think they just fluff up an ounce of feathers and put it into a graduated cylinder with no weight and see how much room it takes up AND they do not then compress it down to see whether or not it actually takes up 0NE (1) unit of volume, also done under some un-stated amount of pressure/weight.

It is not obvious that there are in fact any standards or whether the "weighted piston" could be a piece of paper. So the stated fill power whether 700, 800, 850 or 900 has no meaning except price.

The marmot site says "if your down product says it is filled with 800 down, then it is filled with certified 800 fill power down"

Try searching on "down fill certifications" or "certification of down fill" on the Internet. The is NOTHING. You would think that a lab that certified down would be listed huh???
Jim

There are good internet researchers, and then not so good ones.

International Down and Feather Laboratory.......
http://www.idfl.com/

They have a comparison of the DIFFERENT WORLD STANDARDS for measuring down fill and and discussion on DIFFERENT SAMPLE PREPARATIONS that are used in different parts of the world.

Last year I downloaded a dozen documents on this from them.

I've worked as a researcher in science for 30 years before retirement, and learned the importance of trying and trying different search strategies to locate what you want. The key words YOU THINK should be good aren't necessarily the key words that ARE good.

Here are some words from their page on down and feather testing.

http://www.idfl.com/downfeathertesting.asp
======================================================

Down & Feather Testing

IDFL is the foremost leader in down and feather testing and quality assurance. IDFL performs testing in compliance with all major country standards as well as internal company standards. Content, Species, Fill Power, Average Feather Length, Cleanliness Tests (Oxygen, Turbitiy) and more are all performed at IDFL by an experienced and well trained staff. Feel free to contact us or see our Sample Submittal Form for a full listing of down and feather testing options.
......
=========================================================


Here is the page where they link to documents on testing and standards.

http://www.idfl.com/articles/
============================================================


ARTICLES

We have grouped our articles in the following categories:

* Cleanliness
* Content Analysis
* Fabric Tests
* Fill Power
* General Testing Information
* News and Announcements
* Quality Assurance
* Standards and Labeling
* Sterilization and Licensing Information
* Tolerances

You may need to install Adobe Reader to view some of these files. It is free and easy to install.

==========================================================

Whining is sometimes a good way to avoid learning about difficult tasks yourself.

Please enjoy reading about all of this stuff which you claim does not exist.

===============================================================

After reading every article in the list from the above lab I learned a couple of things:
"Down testing has changed in the last 10 years". Meaning that as we surmised, the new high loft down may just be the same old down measured differently.
The USA system is cubic inches per ounce - with absolutely no reference to how it is measured, compression, weighted piston etc, except that it may be steamed and fluffed prior to testing.
There are many international volume measurement satndards, like different shoe size standards, which may be compared using a table.
NO WHERE IN ANY OF THEIR INFORMATION WAS THERE A DEFINITION OF HOW THE LOFT IS ACTUALLY MEASURED.
so stuff it, the down I mean.
Jim

Did you read the document on "Test names and Standards" and did you understand it? Did you see the standard below:
"Fill Power (Steam Conditioning) IDFB – 10-B"

Did you notice the lack of public access to the many detailed standards that they have?

You might be able to call them and get a copy. It could be something that they sell as a product. There is no real reason why they should freely publish this. The US FTC has done a poor job of standards control in many consumer areas, and private organizations like ASTM step in to fill that void, and to eliminate the need for the more federal regulation - a big selling point in getting corporations to join ASTM.

You pay to get access to ASTM standards, as a general rule. Private industry does things like this.





You probably glossed over the document "Fill Power Evaluation of Conditioning Methods". It says the following, in part, ...



So they are telling you, generally, that one uses a SPECIFIC CYLINDER and weight. The standards for each test will specify the cylinder in detail.

So, it appears as if once again, you are stuck with needing access to standards .... which may or may not be free. And, you may need specialized knowledge to figure out how to obtain them.

Not unusual in engineering. You are taking on a specialized knowledge problem and trying to stuff it into a simple Google search.

At least we can see the differences in the approach of a research amateur and a retired professional.

I won't take the trouble to Google the names of the different test cylinders to see if you can get the details free or not. If you are REALLY interested, you can do that.