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I am starting to think 900+FP really doesn't exist. I have contacted every wholesaler in North America in regards to 900+FP down and they all have laughed at me. They all have said the best down they can get is 850-875. Sure its only 25-50 FP off but its not 900+FP so I wonder where all this 900+FP down comes from???
It's probably a standards discrepancy. I know in Europe they use a stricter method for measuring down than the US. I can't remember now, but I remember some manufacturer had both EU and US listing for their fill power, the US listings were consistently higher.
I'm thinking the EU probably requires a certain humidity level of the test chamber to more accurately represent real world performance. Since most premium down comes from the EU, wholesalers probably go by that standard. The cottage manufacturers may get their stuff retested by US standards?
EDIT: quick google found this a site that defines fill power as cubic inches/30grams. In the us we use 1 oz, which is about 28.34oz. So take 850in^3/30g * 30g/28.34 and you get a, surprise surprise, 900fp rating in the US.
Obviously this site could have their definition wrong, but they do note that US down ratings are higher than EU.
Thanks for the info. I think you got it backwards though. If we measure by the oz (28.34grams) and the EU measures by 30 grams then wouldn't the EU numbers be higher? More weight would allow for more down..
Now if they are selling 850-875FP down by US standards it would be 850 USA = 900 EU and 875 USA = 926 EU. Lets just hope that is the case because if not the 850 EU = 802 USA and 875 EU = 826 USA. They all sell European down so this could be the case but I would assume they would go with the highest number possible an use the EU numbers since this would be a built in selling advantage. I will check back with the wholesaler's to find out more details and how they rate their down.
Thanks again for the info..
You're absolutely right, I ran into that problem when I was trying to figure it out myself.
There are two things I can see causing this discrepancy, 1st the US is just taking the EU rating and swapping 28.35grams for 30grams (which gives a rough estimate of the difference in ratings). This could be due to some dodgy practices or possibly just a lack of standardization in testing (one lab may use 30grams another 1 oz).
The more likely and ethical reason is that the US uses a different, and lighter compression force to test fill power. It could be that compression forces and sample weight don't scale linearly so using a lighter weight with a smaller sample size could potentially give a higher fill power. Imagine, a gram of down may support a gram of compression force by occupying 100 cubic inches. This sample size would yield a fill power of 2800+. This is all conjecture and theory though and I have no data to support it. It just makes the most sense and has the optimism that capitalism recognizes that corporate honesty has a monetary value.
I love quality niche companies. They realize that quality sells far more than branding and as such are willing to give away information that most corporations would deem as trade secrets.
From PHD's site:
http://www.phdesigns.co.uk/techdown4.php?
When delivered to the manufacturer after cleaning and sorting, down bears little resemblance to the mucky substance that was gathered after plucking. Testing of this finished product takes place either by the suppliers or by the manufacturer or both. Suppliers carry out several tests, two of which are of interest to users in the outdoor trade. The better manufacturers will then check what they are getting by repeating the first test (fillpower) for themselves.
Fillpower
This is the test one hears quoted the most and by far the most useful of the laboratory figures. There is no single 'World Standard Fillpower Test'. Each country uses its own system: UK, USA, Japan, Sweden, Germany, etc. The basic elements of the tests are however common to them all.
The down is fluffed up by an air blower, then kept at a controlled temperature and relative humidity for a minimum of 3 – 5 days. Then a sample of the down is taken (20gm, 30gm or 1oz depending on the test) and fluffed up again in the test cylinder. Then a disk of a set weight is lowered down the cylinder to level off the top of the down and the depth of the down is measured.
This establishes the volume which a measured weight of down will fill – the fillpower – whether stated in cubic inches per ounce or cubic centimetres per gram. Cubic inches per ounce is the scale most often quoted the American influence dominating even in metric countries. So when people talk about 550, 600, 700 fill they mean 550 cu in. per oz, etc.
PHD uses a Lorch machine for fillpower testing. This is as near to being an accepted 'world standard test' as there is at present and is approved by the International Down and Feather Bureau. The standard Lorch test uses 30 gm of down, so when quoting cu. in. per oz (one ounce is 28.34 gm) there is an apparent overstatement of fillpower by nearly 6%. However the Federal (FCT) test in USA uses a narrower cylinder and a much lighter top disk, with the result of the same down, one ounce (28.34 gm) tested by the US Federal method, is likely to be given about a 4% higher fillpower figure than 30 gms on the Lorch. So we don’t adjust the figures from the Lorch test, up or down, and we are still about 4% more conservative than US Federal tests.
As a guide to the meaning of fillpower figures:
* 400 Is a normal grade down for bedding or the bottom end of the sleeping bag market, often with more than 15% feather.
* 500 Is already quite a reasonable down, mid to top range for suppliers of cheaper bags.
* 600 A very good down; any supplier is having to work at it to find and maintain this level.
* 700 This is a rare and expensive product. Very few goose downs achieve a higher fillpower than this and for duck down it is the very top limit.
* 800 Achieved by very few downs in the whole world.
Down/Feather Content
Measured by hand picking. Every single piece in a very small sample of down is separated into categories such as down, down fibre, downy feathers, feathers etc etc. Each category is then accurately weighed. (I work with scales accurate to one thousandth of a gram) and the down content then stated as percentages 90/10, 80/20, etc. As a higher first figure means a higher down content, this test is often quoted as another promotional statement about down quality (even 100% has been claimed). Unfortunately that is often the main value of the test – a promotional statement – because there is no single international standard by which these figures are produced and the degree of possible variation makes them virtually meaningless.
As an example, you would be wrong in assuming that a '90/10' down always contains 90% down. In the first place what classification of the word down is being used – how much does it include of the middle categories between pure down and pure feather? There are guidelines, but no accepted worldwide standard and differences in classification exist. Second and even more confusing, by the US Federal Standard the actual down content only needs to be 72% to get the 90/10 classification. It is not that the US standard is lower or less precise: it is just the use of words which catches you out. Some other national standards (German, British, etc) are more in line with what you would expect, but US figures are often used by Far East producers, whose goods go all over the world. And third, measuring down content is a long tiresome business, only applied to the tiniest fraction of the down being processed: it gives a rough guide only and the figures are unlikely to be checked.
In the end the only way for a manufacturer to be sure of what he is saying is to do picking tests himself: and even then he is likely to be spending a lot of time in testing .001% (one part per 100 thousand) of what he uses.
Overall it is better to treat down/feather figures as comparatively unimportant. An experienced manufacturer can tell immediately if there is any increase in the feather content of a down and it will also show up adversely in fillpower testing. After all if extra feathers improved the fillpower, who would care about the classification of the material?
Nice Job on the research. They also forgot to mention the 900FP down…
i think they need to update their website
when you can go into any eddie bauer and pick up an 800 fill jacket for less than $100 on sale pricing … it aint that exclusive anymore
i give credit to EB for bringing the good 800 fill down stuff to the masses … their downlight jackets are so popular that they're locked down at my local EB … old laddies are going in and stealing them
you knot a product is a success when granny shoplifts 800 down … lol
the competitors (big companies that sell 600-700 fill jackets for yuppie prices) are going to have to step up their game
Eric,
One can only hope. Of course there are still idiots that will buy something just because it has a little blocked swoosh logo or a cordura patch with a bolt logo on it. Consumers do seem more informed as a whole though, so things should look good for us.
Dustin I was looking at your CLO chart and I know you said it was built off of limited info. However, it seems to indicate that 900fp of down will keep you warmer compared to a similar loft of 600fp. So 2" of 900fp (7CLO) could keep you warm to around 0deg and 600fp (4.6CLO) could keep you warm to around 20deg. Or have I misunderstood the chart?
Ron,
First off, converting clo or loft or fill power or mass of down to a temperature range is incredibly difficult, at best.
I'm not sure where you're getting the numbers that translate clo into temperature ratings. The standard that I've been using is based off Richard Nisley's research and this thread (which he started):
Remember, there are a multitude of factors involved when calculating a temperature rating.
So based off the chart in that thread, 2 inches give a clo of ~7 which would be comfortable down to around 23F. This compares also to thru-hiker.com which states that 2" of loft should be warm to 30F based of industry standards (this would line up with around 750-800fp down ie 6-6.5clo).
Further complicating issues is the difference between measuring fill power between the EU and US. US consistently has higher rated down than the EU test measures (US uses narrower chamber which provides a bit more support).
Finally the worst part is that I can't find the original data that I used for my regression. (I'm not the most organized sadly, I need to work on bibliographies)
I'm starting to rethink my methodology and now believe that I need to look at how the experiment was setup and completely bypass the conversion from clo/oz. There was no stated surface area of coverage (that I remember) so I assumed m^2 which could be completely false (there may not even be a measure of surface area).
I'm fairly confident that higher fill power down is more insulating, in addition to lighter. This stems from the fact that above 700 fp, the down clusters have to be larger and the percent of feather or other impurities has to drop to achieve such measurements. So from common sense my numbers show a general trend, I've just lost faith in their accuracy. I'll see if I can't find the original charts and refine my analysis.
Sorry I can't be of more concrete help, but many intelligent minds have tackled this issue and they all come up with the same thought "Down insulation is a whole lot of clusters…"
Dustin
It's no worry that you can't be of more concrete help. I know that when you start talking about Temp ratings, down, and even CLO in general it can be very unconcrete. Mainly because people are different in make up.
I was more or less just throwing something out into the land of theory to mull over. The main reason I asked was because it could possibly mean that you could get away with even less down when it's a higher fill power. If the CLO of higher FP down is greater then a thinner 900fp bag would be as warm as a thicker bag of less FP. In theory at least. That would mean another weight savings because your volume of needed fill has decreased as well.
My CLO ratings were drawn from the thru-hiker forum, memory of those posts, and the Mammut sleep well document on their website.
Rob
Heh, we also have the standard metric-customary issues (I blame you brits for that one, switching to metric, like the French, and leaving us all alone with a wacky a set of units).
Your 0 degrees I'm now assuming are in Centigrade, mine in Fahrenheit which gives us much closer numbers. So yes you would be right for your temp ratings (or as right as anyone can be).
Thanks for reminding me about the Mammut Sleep Well guide. Looking at their numbers and specs, I think my calculations are fairly accurate now. 2" of 800fp down would give a clo of ~6.5. This is around 30F/0C as mammut claims based of EN13537 comfort (not lower/extreme limits). It also falls in line with Thru-Hiker's recommendation for loft that 2"=>30F.
Checking against 2.5"=>20F as thru-hiker claims: 2.5*3.26=8.15clo. Mammut's guide claims that 8.5clo has a women's lower limit of around 17F/-8C which confirms thru-hiker. I'm going to conclude that thru-hiker's chart is based off 800fp down.
That said, I still can't find where Richard Nisley (i think it was his post) said that 800fp down has a clo/oz of 1.68. Still looking though. I've seen other posts that claim 850fp=2.53clo/oz which is significantly higher (and I think wrong or ideal conditions based off the EN13537 scientific ratings and thru-hiker's experiential ratings). The other source does still mention 550fp=.7clo/oz though so I'm trusting that number is accurate.
If so, yes you could use less 900fp for same temp rating. 1.8" will give you 0C/30F compared to 2" with 800fp. Subsequently 2.25" of 900fp is about the same as 2.5" 800fp for a 20F/-7C quilt.
Doing some quick calculations based off the dimensions of thru-hikers quilt. For his 20F bag he had 72"x45"x2.5" volume. That's 8100 cubic inches. Using 800fp you need about 10.1 oz of down. Using 900fp with an assumed equivalent clo value you only need 9oz of down. But if we factor in that 900fp is warmer than 800 AND lighter, we now only need a 2.25" baffle height. That's a total volume of 7290 cu.in. Divide by 900fp we find we only need 8.1oz of 900fp down to reach the equivalent weight.
So our 17oz down quilt drops to 15oz for same warmth just by switching to 900fp. You also get some minor weight saving from less baffle material (using another model for quilts it's about 0.5 oz). That's pretty significant.
This I think explains how PHD has been able to make a full mummy bag for 12oz using 900fp that they rate to 46F.
In practice, I would ignore the clo increase of 900fp and just factor in the weight savings. Larger down clusters I hear degrade faster than smaller clusters. So initially you'll get a warmer bag for your design constraints, but it'll satisfy your design constraints for a longer time, increasing it's value. Depends on what you want, the lightest of the light, or a light bag that will satisfy your needs for years to come.
I'm afraid Dustin you can't blame me for the whole metric problem. I was born and raised in Macon, GA. I've just lived over here for the past 8 years. I'm the second phase of the recolonization of the 'mother land'. Grey squirrels were the first phase.
I've come to just ignore the stated ratings to some degree, but maybe I'm just cynical. If only one company is selling 900fp down then it makes me wonder why it's only them that can get it. Also I always over fill by at least 10% just to be sure. The only easy source of down from Europe over the internet is a German company and the highest they sell is 860. I've just assumed that it is as good as 900 by the EU standard.
Maybe one day someone will bring some agreement and honesty to the ratings.
Hey Rob, feel free to move to Texas and help re-colonize it.
That said, I still can’t find where Richard Nisley (i think it was his post) said that 800fp down has a clo/oz of 1.68. Still looking though.
That one is right here
Incidentally, the 2.16kg/m^3 mentioned there works out to 800 in^3 per ounce … fully lofted 800fp down.
Jim and Eric,
Thank you! Best Halloweeen presents ever! Jim, It's been killing me that I couldn't find that post.
Eric, I had found that pdf, but through the links I followed I could only get the German version (I was on the english page as well) and it was annoying me to not have a translated copy.
There is an interesting side effect of all of this though. If the US method uses a narrower cylinder for testing of FP and gets higher results (neglecting any special treatments the down is put under), I wonder if narrower baffles would artificially boost the fill power of your quilt by providing more structure for lofting. You'd lose some weight advantage by needing more baffles, but this is a thought exercise in optimizing warmth/height or volume, not really warmth/mass.
Thank you! Best Halloweeen presents ever! Jim, It's been killing me that I couldn't find that post.
Well, the benefit is mutual. I wasn't aware of it but knowing what to look for it was easy enough to find and now it's been saved in my "Nisley Stuff" bookmarks folder.
(Found using google's site specific search feature … searched on nisley 1.68 site:backpackinglight.com
What about cheap down for prototyping?
I would love to find some cheap 650 or 750 simply for making test quilts or even throws as Christmas gifts.
Anyone have a source for cheap down in bulk?
Seven wonders is way too expensive. Hammock gear sells 800+ down for $6.50/oz which is steal compared to $6.00/oz for 600 down.
I'm still looking, but I recently came across a site that was selling 500-650 range (can't remember which) for around $3/oz…can't find it for the life of me though =/
not the original site i was thinking of, but if you just want feather fill for prototyping this might work. Pretty darn cheap at around $0.75/oz
The best way I found to buy cheap test down here in England is inside a pillow. I looked for the websites that listed the fill power of the down in there pillows. Some worked out as cheap as £1.50 per ounce for 600-650 fill power.
i just ordered the quilt kit from thru hiker, added 3 oz of 900fp down
for $25. $8/oz for 900fp aint bad. You can only get that price if you order one of their kits that includes down.
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