The differencec between down is...???

[lazy river road]

As I understand (correct me if im wrong) the difference between different fill down is how packable it is. For instance, 16oz of 800, 850 or 900 fill down in a TQ, in theory (or at least in my head ) should all have the same temp rateing. But the 900 will just pack smaller then the 800, correct? The reason I ask this is BC with WBGuy's introduction of his Black Mamba, I compared other winter TQ's with the same amount of fill. I noticed that different vendors rated their quilts differently even though their was the same amount of down fill in each. So why is it that quilts with the same amount of fill have different temp ratings? Is it BC of material, construction, or just BC different vendors rate their quilts differently depending on what UQ they imagine people using? Just wondering...a pondering question.

[JerryW]

The number refers to how many cubic inches one ounce of down will fill. For instance - 1 ounce of 800 fill power down will fill up 800 cubic inches.

So, for the same number of ounces in a quilt, the higher fill power will make a thicker quilt, and theoretically warmer.

Jerry

[jofish]

As always, Jerry provides a clear and quite correct answer.

[warbonnetguy]

you have to look at the size of the quilt too. take the jrb quilts, the old rag is a winter quilt rated to 10 deg, the mt rogers has the same amount of fill but it's rated to 30 deg. this is mainly because the mt rogers is much bigger, so just because they have the same fill doesn't mean they are the same thickness.

looking at my quilts or anybodys, the longs have more down in them, but that doesn't make them warmer, because they still have the same amount of down per area.

also, the higher the fill power, the less wt of down you need to get the same warmth. say you have a square quilt that's 6'x6'x3" it will take more weight of 600 fill to fill the quilt, less weight of 900 fill. when filled they should both be the same warmth, the higher fill just fills the volume with less weight/down

take for instance the yeti3, it has about 6 oz of 850 fill. if i used 425 fill instead, it would probably take about double (12oz) to fill the same quilt. the higher the fill power, the less you have to use

[lazy river road]

aaahhh I see so the higher fill you have the less down you need to fill the area. So filling a quilt with 6 oz of 850 fill is obv lighter then filling it with 12 oz of 425 for the same temp rating (assuming the quilts are the same size).

Ok so what about if you fill a 6 x 6 x 3 TQ with 16 0z of 800 down vs 16 oz of 900 down. The TQ with the 900 fill will be warmer? Or will it just be more compressable when packing it down?

So if im understanding correctly, the higher fill the down is, the less you need to fill in the quilts to create the same warmth you would get with lower fill down which you would need more of to to get the same warmth as the higher down?

All this stuff is really cool to learn about...Each one of you vendors put such different little touches on all your gear that they are all so closley related but yet seem so different. Im just trying to learn about the concepts behind them all. Great stuff, thanks guys.

[tammons]

In theory the 900 fill down would create 12.5% more loft than the 800 fill, so if the tubes were designed for the additional loft it would fully loft. If just stuufed in the 800 design it would be over filled and puffy.

[lori]

Ok so what about if you fill a 6 x 6 x 3 TQ with 16 0z of 800 down vs 16 oz of 900 down. The TQ with the 900 fill will be warmer? Or will it just be more compressable when packing it down?

So if im understanding correctly, the higher fill the down is, the less you need to fill in the quilts to create the same warmth you would get with lower fill down which you would need more of to to get the same warmth as the higher down?

16 oz of 800 will be less down than 16 oz of 900, and the 900 will fill more space - but it won't necessarily be warmer. At some point ( I understand the concept but numbers are another matter) the better down becomes less effective unless you give it space to loft. I know that the JRB quilts routinely have a couple -three ounces of overstuff and that seems to work well... but if you jam more down into the space at some point it will begin to be too compressed and not as warm as it could be. You have to balance the volume of the quilt, the fp of the down, and the dimensions of the quilt baffles so that the end result is a uniformly warm quilt.

[tammons]

The ability to insulate comes from an insulations ability to trap air.

In theory 900 fill down should be warmer than say a down feather mix due
to the fact that high quality down is almost totally comprised of the little fluffy
feather bits so it should trap air better. Cant remember what you call them.

Compared to something like Climashield XP, it does not take as much loft for Climashield to give the same amount of warmth. IE a 1.2" batt of climashield is roughly equal to 1.8" of down loft.

High quality down is still lighter though and more compressible.

Climashield in just its insulating value is roughly equl to 550 or 600 loft down.

[lazy river road]

aahh thx guys, I just learned so much and this all makes a lot more sense now. SO if you have 16 oz of 800 fill at 3 inch loft and 16 oz of 900 fill with 4 inch loft the 900 fill is going to keep you warmer, and be more compresiable. But if the 900 fill only lofts to 3 inches, it will to be to overstuffed, not providing any more warmth then the 800 fill. This is the general concept. Lori I get now how their has to be a balance. thanks again.

[Just Jeff]

Sounds like you got it. Now for another complication...

Fillpower is measured under lab conditions...the down is very dry and it's not weighted down by a layer of nylon on top of it. In field conditions, you'll have some degree of moisture and the down will have to support some sort of shell material as a top quilt. Why is this important? B/c higher fillpower down is wispier...shell material and especially humidity has more of an impact on 900fp down than it doesn 700fp down, just as a function of having "better insulating" down clusters. I've read that anything over 750fp has about the same insulating value in the field. No idea how accurate that is, but I wouldn't spend a bunch of extra money to get 900fp if 800fp was available for cheaper.

That said, I use Ed Speer's 900fp down b/c he has a good price and he's a valued member of this community...I like rewarding responsive gear makers with my business.