Down fill

[saimyoji]

I understand the fill power rating on down. Some bags I've been looking at recently say 70% or 80% down clusters. I assume that this means the remaining 20-30% are down "shake," not clusters, but still down? Would this have a large effect on the insulative properties? I'm guessing it would, but how much? A 650 down bag with 80% clusters vs. a 800 down bag with 70% clusters? Or, are the two connect: 650 means that there is some shake. 800 means there is practically no shake, all clusters? Is there really no way to tell, except experience?

Any thoughts?

[Tinker]

"Down" consists of down "plumules" and feathers. The plumules are what most people think of when they think of "down". I don't think there is a down which is 100% plumules, and the highest loft I can think of is 900 (the height (in mm) of the down in a cylinder (which I believe is 1,000 mm in volume - someone else correct me if I'm wrong), when weighted by a one ounce weight. The higher the number, the higher the loft. The lower numbers have more feathers and broken plumules, requiring more of it, in weight, to accomplish the same insulative value.

[rafe]

My understanding is that the "fill rating" (numbers like 600, 650, 800, etc.) equals the # of cubic inches per ounce (weight) of down fill. That kinda makes sense to me, but I can't vouch for it being the truth.

[Appalachian Tater]

Fill power is volume per ounce. Percent down tells you the ratio of down to feathers. There is probably some correleation but it is not direct and they are two different things. "Shake" is a term related to cannabis.

[saimyoji]

"Shake" is a term related to cannabis.

Yes, I know, that was the best way I could describe it at the time.

So the % clusters is pretty much the same thing as the fill power? To say 600 fill implies a greater amount of feathers, broken plumules? (70-80% clusters) And a higher fill power means less broken feathers/plumules, more clusters? Now that makes sense. Just a different way of saying it.

[Appalachian Tater]

No. Down is different from feathers.

Percent down is the ratio of down to feathers and applies only to mixtures. A mixture of down and feathers is of lesser quality than pure down. I don't believe "fill power" is ever correctly used to measure the quality of a mixture of feathers and down.

Down fill power measures the "quality" of one hundred percent down and applies only to pure down and not mixtures.

So 600 fill power down is of better quality than 70% down simply because it is all down. (Implied with the 70% down is 30% feathers.) The insulating quality of feathers is nowhere near that of pure down. A mixture of down and feathers is highly unlikely to contain good quality down or it would have been separated for sale as it is so much more valuable.

Pillows and sometimes comforters will often have a percent down stated. The better quality ones will have pure down and then would state fill power. A sleeping bag of any quality at all would be all down without feathers.

Good quality upholstered furniture usually contains a percentage of feathers because pure down is not well-suited for this use.

[saimyoji]

So, if you bought a bag that claimed to be 650 down on the ad, but when you looked at the tag affixed to the bag and it said "At least 80% down clusters," what would you think? That the bag was not 650 down, or that it was 650 down, just part of that was not clusters but feathers?

I don't think the fill power is not related to the % clusters in the bag. I've seen two different bags rated at 20* one with 650 down (80% clusters) and 600 down (85% clusters).

Now I'm just confusing myself. If you haven't cut the tags off your bag, go check it out.

[Appalachian Tater]

Yes, if a bag is 100% down and is 80% down clusters, the other 20% is broken clusters, not feathers. Down is three-dimensional and fluffy, when it is crushed or broken or stored compressed, the fill power (and insulating ability) is lowered.

650 down with 80% clusters and 600 down with 85% clusters are very similar all other things being equal. I'm not sure how exact the percentages are, it's probably a judgement call by someone experienced. You could probably just compare ounces of fill with these. But 600 down with 75% clusters (the minimum percentage by law in the U.S.) is much inferior to 800 down with 95% clusters.

But it's not that simple. Goose down is fluffier (higher fill power) than duck down. Cold-climate birds have fluffier down than warm-weather birds. Different kinds of geese have different qualities of down. Eiderdown is warmer than other down even at a lower fill power.

In addition, no down is absolutely 100% pure, there are always a few featers. There are always some broken clusters as well.

In a sleeping bag, a lot of the weight is from the shell, liner, and zipper. You can really only directly compare bags in the same line from the same manufacturer by weight of fill. Marmot, for example, has different fill power down in different lines of bags, as do the other manufacturers.

The best thing to do is go to an outfitter and pick up and toss into the air and squeeze the different bags within a manufacturer's lines and compare them to each other and to other qualities of down and weights of fill. Ultimately, you can't trust a tag as a sign of quality these days. If a down bag is big and fluffy but light, it's of better quality than a flat, heavy bag.

[saimyoji]

There are always some broken clusters as well.

"Shake"

Yeah, your last paragraph I agree with. Unfortunately, thats often not possible. Especially when online retailers give great deals for a short period of time.

I see what you mean about the fill power vs. % clusters. Unfortunately I'm back to square one: no way to tell but try the bag out.

[Appalachian Tater]

So send it back if you don't like it. And stick to the better manufacturers (Marmot, Feathered Friends, Western Mountaineering, Montbell, etc.) that use good down and stand behind their products.

And don't smoke your down. It smells bad when it burns.

[saimyoji]

So send it back if you don't like it. And stick to the better manufacturers (Marmot, Feathered Friends, Western Mountaineering, Montbell, etc.) that use good down and stand behind their products.

And don't smoke your down. It smells bad when it burns.

Well the examples I've been using are not bags I've purchased, just ones I've been looking at. I actually just grabbed a Marmot Pinnacle off backcountrygear as its on sale, as I posted in another thread. Looking forward to that (800+ fill).

And no, I haven't smoked anything in decades. Well, one decade at least.

[EWS]

Down "fill power" numbers mean nothing when compared between different manufactures, as there is no standard form of measurement. You get what you pay for from the better manufactures and that is it.

[saimyoji]

Well the Pinnacle arrived today and I must say the loft is ALOT different from lower fill power bags. The tag says at least 90% down (goose down 800+ fill). Can't wait to test it out. Very comfy.

Now I have a question regarding high fill power bags: since they loft so much and hold so much air, is there a best way to squish the air out when stuffing them into the stuff sack? I don't want to damage the baffles. Any special stuffing/handling tips?

[nitewalker]

i have also heard that down fill power maxes out at 800. correct me if im wrong..also i assume feathers are better than the clusters... all i know is whatever down bag i use, im never cold and im usually too warm..i belive this problem arises because i bring a bag that is usually rated 10 to 15 degress lower than the temps i am expecting....better safe than COLD.....peace , nitewalker

[Lyle]

Check out this Trailcast for an excellent discussion of down and how it is rated from one of the owners of Western Mountaineering - Premium Sleeping Bag manufacturer. The down discussion is in the second half of the podcast.

http://www.trailcast.org/programs/44

[saimyoji]

Some interesting comments from the maker of LuxuryLite Gear:

Why Fill Power Rating is Not Too Useful

Why don't we list the Fill Power (600, 750, 800, 900, etc) for the LuxuryLite "V" Bag? Well, bottom line, I don't know the fill power of the down in our bag. When I designed and specified this sleeping bag for the manufacturer in China I specified the length and width, and the full-length chest zipper; and I specified only three performance specs: [1] it must be down filled, [2] It must weigh less than 2 lbs and [3] it must have a minimum loft of 8 cm.

If I would have specified a 'Temperature Rating' or a 'Fill Power' I would have no way to argue with the manufacturer. Even with the language barrier, we can both weigh a bag and we can both measure the thickness. I have slept in this bag at 33 degrees on the LuxuryLite UltraLite Cot with Cool Mat inside a backpackers tent and was very warm.

The super-duper (950!) down now being promoted is certainly amazing stuff. But not the best for a sleeping bag that gets compressed into a pack all day long. Let me quote this honest European web site:

http://www.warmpeace.cz/en/index.php?sec=27 "The quality of down is measured by its content (90/10, 80/20, 70/30 = the ratio of down plumules and feathers), and its fill power, ie. the ability of 1oz of down filling up as much space as possible. The best quality goose down (100/0), would have the fill power (FP) of 950-1000 (1oz of down fills up 950-1000 cubicinches of space). Such a super high FP is impractical because it takes a long time to reach its maximum loft. For sleeping bags, where frequent rolling compresses the down fill, a mixture of down plumules and larger, more resilient down parts is desirable. This assures an optimal loft and durability."

What he is saying is that if you owned a super-duper sleeping bag made from 1000fp down, that bag would not fluff up for hours, if ever. (A little dirt, dust, or body oils will keep the plumules stuck together.) The feathers in the down make it fluff up much faster. That is why the LuxuryLite "V" bag uses 90/10 down with 10% feathers to make it fluff up fast.

Bruce A. Warren, P.E.
LuxuryLite Gear



http://www.luxurylite.com/fillweight.html

[The Will]

What he is saying is that if you owned a super-duper sleeping bag made from 1000fp down, that bag would not fluff up for hours, if ever. (A little dirt, dust, or body oils will keep the plumules stuck together.) The feathers in the down make it fluff up much faster. That is why the LuxuryLite "V" bag uses 90/10 down with 10% feathers to make it fluff up fast.

I'm curious about this rationale. I'm not immediatly brushing it off it, but I can't connect how feather content would positively correlate with the rate that the down plumules reach their maximum loft. I can see how a plumule representitive of 600-fp would reach its maximum loft before a plumule of 800-fp would reach it's maximum (just as a 3/4 length self-inflating pad would fill before a full length pad), but I don't see rate of expansion differing wildly one way or the other.

I believe that the rate of expansion of a bag to its maximum loft based on fill power is a mute point, assuming that the down bag sis given some gentle shakes and thumps immediatly after removing it from its stuff sack.

You can tell we're gear nerds when we talk about this stuff at length.

[saimyoji]

What he is saying is that if you owned a super-duper sleeping bag made from 1000fp down, that bag would not fluff up for hours, if ever. (A little dirt, dust, or body oils will keep the plumules stuck together.) The feathers in the down make it fluff up much faster. That is why the LuxuryLite "V" bag uses 90/10 down with 10% feathers to make it fluff up fast.

I'm curious about this rationale. I'm not immediatly brushing it off it, but I can't connect how feather content would positively correlate with the rate that the down plumules reach their maximum loft. I can see how a plumule representitive of 600-fp would reach its maximum loft before a plumule of 800-fp would reach it's maximum (just as a 3/4 length self-inflating pad would fill before a full length pad), but I don't see rate of expansion differing wildly one way or the other.

It would seem that a bag with more differential cut would loft faster as it would not restrict the down lofting....

I believe that the rate of expansion of a bag to its maximum loft based on fill power is a mute point,

Does this mean we can't talk about it?

You can tell we're gear nerds when we talk about this stuff at length.

[slow]

You really dont have worry if it's W.M,F.F...all others YES.

[slow]

M.B. makes good bags...but not if tall and side sleeper,they lie about knee size.

My WM mitylite smokes it for no hood,size,and a 40F bag that keeps me warm at 30f and only boxers.

Save your money for F.F W.M and be happy.