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