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Ivo Vanmontfort
(Ivo) - MLife
A little goose down test on 02/20/2012 13:52:16 MST Print View

apology for my poor knowledge of the English language.
therefore, my comments will be limited
I need your thoughts
I did a little test with two types of goose down.
The first came from les ateliers de lastour.
He is also the supplier for Valandre.
Ik used the ‘duvet d’oies grises du Périgord 95/05 réf 021000LD de 750 à 820 cuin.

Van donstest

The second is the 900 fill power white goose down from Thru-hiker
Van donstest

In both cases I put 20 grams down in a large glass tube. I kept the tube horizontally when I shake the down to move freely.
Then I put the tube vertically.
Van donstest

The loft of the two products seems remarkably similar
About 59 cm for the ‘duvet d’oies grises du Périgord 95/05 réf 021000LD de 750 à 820 cuin
Van donstest

And 61 cm for the thru-hiker stuff
Van donstest

The loft of the two products seems remarkably similar but the stuff of thru hiker is much easier compressible.
For testing, I used a PU foam disc (37 gram) to compress te down clusters
37 cm for the duvet d’oies grises du Périgord 95/05
Van donstest

and 28 cm for the 900 fill power white goose down
Van donstest

The clusters of the French down d'Oies grises du Perigord 95/05 looks more robust but seem much less uniform than the down clusters of the 900 fill power white goose down.
More featers can be found in the French down while thy barely be found in the white goose down.
The air spaces between the gray goose down are much larger while the white goose down has a more compact look.
I have the impression that the small feathers also give much more structure and support to the down clusters than when they were absent.
This perhaps explains, i think, why the Thru-hiker stuff is much less resistant to pressure.
It must be said that the thru-hiker down have a much smoother look.
What is the impact on the insulation, I have no idea.
You will probably have different values if you take a wider tube or the down column is lower because the down clusters also cause pressure on the lateral wall.
Can we make conclusions?
More on my blog

Edited by Ivo on 02/20/2012 14:04:10 MST.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: A little goose down test on 02/20/2012 14:02:40 MST Print View

"Can we make conclusions?"

I saw this test for the first time about thirty years ago at Western Mountaineering. The only things that concern me are the diameter of the tube, the mass of the down that you place inside the tube, the mass of the PU disc that you put on top. I don't know what they are supposed to be, but there is a need for standardization. Also, I think you want to monitor the humidity of the air.


Daryl Daryl
(lyrad1) - MLife

Locale: Pacific Northwest, USA, Earth
Re: A little goose down test on 02/20/2012 14:46:38 MST Print View


I only wish I could do as well as you in a second language.

I don't know much about down but it seems that you have done a pretty good job of making an apples to apples comparison of the two down samples.

Other things being equal I would prefer insulation that resists compression. The resistance to compression might be a problem for those who are into small volume as well as light weight. (i.e. it would be harder to compress into a small stuff sack). Small volume doesn't matter much to me. I carry a large volume pack.

Looking forward to comments from those who know more than me (i.e. they actually know something).

Dustin Short
(upalachango) - MLife
Re: Re: A little goose down test on 02/20/2012 15:18:47 MST Print View

Actually I'd have to disagree with you Bob.

The value of this test is specifically that it is a side by side comparison in an uncontrolled environment. Granted replication of the test becomes impossible but for a comparison it's pretty nice.

By using 20g each in the same size tubes he's showing that the 95/5 down from the french source and thru-hiker have the same fill power in real world situations. However thru-hiker's down compresses better and has a more homogenous density (uniformly sized air pockets).

The french source claims the fp of their down is between 750 and 820...if we assume that's using the EU standards which roughly translate to 100fp ratings lower than the US standards we get 850-920fp in the US. So thru-hiker's down is at least equivalent to 850+ in real world environments.

This kind of reinforces why WM still claims only 850 although many say their down often tests higher. Thru-hiker obviously has a quality source for their down, however the rating may still be optimistic for real world use, however it still is a high fp none-the-less.

From WM directly:
"Fill Power Testing
To perform a certified test, a sample of down is sent to an independent laboratory. There the sample is placed in a large screened box and allowed to condition for 5 days before being tested. During this time the sample is stirred, mixed, and blown with a warm hair dryer. This conditioning is intended to stabilize the sample so that consistent results may be obtained. Then a 1 ounce sample is drawn and placed into a measuring cylinder. A piston weighted to 68.4 grams is placed on top of the down and when it comes to rest the volume of the down is measured in cubic inches. In spite of 5 days of conditioning, the laboratory will publish their results with a plus or minus 5% error. This is a full 10% range and for an 850 fill test, results in an 80 point variance! Furthermore, conditioning actually improves the sample by drying and blowing out dust and other small particles while the down at the factory remains unconditioned! This is what we mean by an Optimistic fill power rather than a Practical fill power rating."

Colin Krusor
(ckrusor) - M

Locale: Northwest US
Test on 02/20/2012 18:43:35 MST Print View

Bob, I have to agree with Dustin. It seems to me that the purpose of the tests performed by the OP was to compare his two samples of down, not establish a fill power rating that could be compared to published numbers. He doesn't need any kind of standardization, and I don't see any reason for him to be concerned about humidity. As long as he treated his two samples the same way, his tests seem well planned and valid.