# Thread: Calculating fill power from lofted down

1. ## Calculating fill power from lofted down

For all the goose down gurus out there...
I have some down of unknown fill power and need to calculate how much to use in an UQ. I made a cardboard box exactly 12" x 12" x 12" and filled it with 1 oz of the down in order to calculate the cubic inches of loft it had. To make sure all of it had a chance to loft, I shook the box a bit and let it set for several minutes. It measured 7" deep or about 1000 cu in. I've never heard of 1000 fill power down, so I thought it might settle overnight. It didn't.

Have I gone about this process in a reasonable enough fashion that I can calculate my quilt based on the 1000cu in per ounce that my down lofted to? I've never calculated fill power from lofted down before.

Thanks for the help.

2. Somewhere I once saw official contraption that is used to determine fill power. It has a vey lightweight plunger on top of the down. That's the part you are missing and therefore getting high values.

3. ## Interesting

Sounds like a sound method to me. What do the experts say? Maybe you've found the "El Dorado" of feathers?

Hope to see you and all the women in your life soon DM!

4. I could be wrong in my memory, but I believe you need to cover the down with a 1 oz weight and then measure to give you the proper fill power numbers.

5. ## Pyrite, me thinks

I think the official test has a small weight on top compressing the down a bit before its measured. Just spitballing here, but try cutting a 3/4" or 1/2" piece of foam to cover the foam (polystyrene or open cell foam) and then re-measure the loft with it on top. Could also use a peice of fleece or something similar...
Think of it this way: in your bag/quilt, the down will still be compressed a bit by the weight of the top material and/or surface tension of the fabric when you overfill the chambers.
Realisitically goose down tops out at ~860 with no feathers. 900 FP is marketing. Eiderdown (~\$200/oz.) MAY be realistically a 900 FP insulator.

6. ## Second possibility...

Given that pure down is ~860 FP and feathers are very low (for the sake of argument say 260 FP, to make the math easy) - stick you hand in there and VERY GENTLY move the down around. If you see or feel feathers or bits of feathers, you need to "de-loft" accordingly.
For me, I'd use 800FP as the basis for how much down to use if the down looks like it is feather free. If you thinks its 10-20% feathers, use 700FP for the calculation...
Given that you measure it at 1000FP uncompressed, its probably one of those two.

Hope that helps....

7. Thanks for the help guys. There's very little info on the web about the method used for commercial testing. I'll try a weighted piece of cardboard and see what the loft measures. This is pretty good quality down. There were only a couple of short feathers in the ounce sample I used. I'll post my results tomorrow.

8. After putting a heavy piece of cardboard on the lofted down (about 2.5 oz for 12" square) the down measured between 4.5 and 5" of loft. This makes it around 650 -700 fill power, which is more realistic. The lower fill power will add 3-4oz of weight for the quilt.

Thanks again for the input.

9. ## fill power testing

It may be a little late, but this post may help others searching for the same answers (as I was this morning).
Marmot does a great tour of their down testing lab available here:
Summary:
Down is first conditioned to a standardized temperature/humidity and then it is tested in a large cylinder (looks about 20cm in diameter), marked for Fill Power. Fill power (FP) is expressed as cubic inches per ounce (in³/oz) although I suppose metric folks could use cm³/g; however, "800 FP" would be 462cm³/g which doesn't sound as impressive.
Like Detail Man's fill-power box, Marmot places a 63gram (2.22 oz) cover/weight on top of the down totally covering the down and allows the down to settle. It is important that it compresses evenly.

I think Detail Man's box a great way to test at home, providing you can test at room temperature and average-low humidity.

I think I would agree with Wikipedia where it says 750+ FP is considered excellent and I'd also agree with HanginLight that 900 FP is a lot of hype. There are certainly diminishing returns as the price goes up. For example, Eiderdown (which comes from the Eider duck) has excellent down clusters that are clingy and stick well to one another. I gather that this would make a 3-D lattice of sorts, creating a stronger structure that resists the test weight, and is the reason for the higher FP scores. Cool? I think that's cool too, but it's hand-picked from the nests by virgins for \$65 an ounce... Not so cool anymore.

I'm sure there are manufacturers out there pondering the idea of using "effective fill power" scores to boost their ratings into the 1000's and they can justify it by the use of ultra-light materials that exert a lot less compressive force (than the 63 gram standardized weight), which allows the down to loft even more. In fact, many people on this forum probably already have quilts and underquilts that operate at an effective fill power of 1000+ (like Detail Man's uncompressed 700-ish FP hitting "1000 FP") due to the super-light weight fabrics used. Grizz's cuben underquilt comes to mind. But in the age of cuben and momentum 50, why do people over-stuff? The down should loft more than its rating under a lighter fabric...unless...

Speaking of down hype... I would even go so far as to say goose down (best) vs duck down (not good) is irrelevant hype too. 800 FP goose will weigh and fill the same as 800 FP duck, but duck is almost half the price. I've been looking at prices for 800+ FP and I can get duck for \$4.66/oz or goose for \$7.20/oz from my local factory.

On a related note, does anyone else find it a little funny that "Canada Goose" jackets are made with DUCK down?
DT

10. you won't be able to tell without following the standardized test method exactly i don't think. what you can tell is how many feathers are in there, you want mostly down and as little feathers as possible, but it will be tough for you to figure the FP at home

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