A little goose down test

"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.

–B.G.–

Ivo,

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).

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."

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.