800 ci/oz Fp down, if poured into a container, will puff up and fill a container of 800 ci, is that right? -BillyBob, down is tested in a cylinder with a 1oz* weight applied. 800 fill down would consistantly loft to 800 c.i. under this weight.
without a weight, it will "loft" to much larger area.
*iirc
So from what I have been learning from alittle research is that your R value is based on a combination of various things. Like having trapped air pockets and air flow as well as the thickness of your insulation. Over-stuffing a cavity decreases air movement which will increase your R value but it also decreases your air pockets which in turn lowers your R value slightly, BUT it also causes the baffle to expand from being overstuffed, thus increasing the thickness of insulation as well as resisting being compressed and in turn increasing the R value.
Spray foam utilizes the concept of Trapping air movement as well as prohibiting moisture from entering the insulation and sapping the R value. The microscopic air pockets in spray foam are extremely small compared to that of natural insulation like Down or Fiberglass but yet it insulates much more effectively. This is because there is NO air movement at all in the insulation.
I agree that a happy medium is needed for Down type insulation. But I still think that medium is met with over-stuffing baffles because it decreases air movement and lowers the ability for compression and also increases the thickness of the insulation. The combination of all of this provides a much better insulation factor than loose filled baffles IMO.
Some good articles for yall to read on how insulation works and how Conduction and Radiation works. I just learned that I should be putting my Reflectix on the OUTSIDE of the UQ instead of the inside up against the body. Reflective barriers need to face an open area of heat in order to properly reflect any radiant heat vs being right up against the heat source.
http://energy.gov/energysaver/articles/insulation
http://www.drenergysaver.com/insulat...nsulation.html
This is a great discussion. I am learning alot more about how insulation, conduction, convection, and thermal radiation works because of this.
Thanks for the reminder, I remember reading that in the past somewhere, after you refreshed my memory!Originally Posted by te-wa
So with the weight of 1 oz ( and I suppose there is a certain diameter container that is also part of the standard? So that the oz per sq.in. pressing on the down will be constant? or maybe not ) So 1 oz of the 800 fp will fill 800 ci, in a closed container with a 1 oz wt on top. If we put 2 oz into the same container, since I assume the 1 oz lid is free floating, the down will now rise to ~ twice the height, more or less?
So loft is doubled with twice the down, right? ( assuming the only variable with the container is that the 1 oz movable lid will allow the height to go up or down ). So let's say the height of the container has now gone from 2" of "loft" to 4" with twice the down. It has now increased warmth rating from say maybe 30F to zero f, more or less.
Now double the amount of down but do not allow the lid to move. Put that down into a container with a fixed volume which only allows the down to expand to the original 2", and maybe another to 3" and another to about 3.34 just for fun. These would all be "overstuffed" space compared to the increase from 2" loft with 1 oz down to 4" with 2 oz down.
So, do you think 3" of loft achieved with 2 oz of down warmer, as warm, or less warm than 4" of loft achieved with 2 oz of down? I don't know.
So you might be saying " Hey Dufus, you are approaching it backwards". That the loft is a given, say 2.5" single layer loft. But we can achieve that with say 10 oz of X FP down in a given size quilt, or we can achieve the exact same loft by adding 2 more oz for a more dense fill with fewer gaps and spaces. Very true, but you could also add the 2 oz of down and just let it loft to it's maximum ability. ( I used th 100% overstuff example just to make it easy to calculate loft, which is doubled) I suppose loft- if you just let the above quilt maximize loft- would go from 2.5" with 10 oz to 3" with 20% more down or 12 oz total. Which way is warmer: 2.5" with 12 oz down or 3" of loft with 12 oz of down?
Again, there may well be a happy medium, maybe 20% overstuff is that HM. Or maybe risk is on to something at least with down insulation: all the loft you can get per oz. I have no idea!
I have 30 degree Speer Peapod and a 20 degree Speer Peapod. The only difference between the two is that the 20 degree model has two more ounces of down. The baffles, chambers and material are otherwise identical. A Peadpod is used as both top and bottom insulation. Having used both, the 20 degree pod does loft more and is warmer. Based upon that, I cannot help but believe that more down does provide more warmth.
Or maybe 94.25 g weight...http://www.abflo.info/usa_labels/test_methods
Well, sure the 20F is warmer, because in that case the pod allows more down to provide more warmth by providing more loft. In fact, my pod is def more to the understuffed end of the spectrum. Just look how you can move that down all over the place to get even more warmth exactly where you want it, with more loft, in the areas where I move the down to. In fact, I'm sure I could add quite a bit more down without reaching what might be defined as "overstuffed". Mine looks like the chambers might be capable of 4 or 5" of loft when I shift the down into smaller areas, but it is only rated at 2.5" per chamber (I think it has 2.5" baffles) . Probably the most understuffed quilt out there, except for the 30F model! ( and yet one of the warmest approaches I have used) Stairguy has added 22 oz of down to his PolarPod, and looks like there was plenty of room for it. And from the looks of it, it resulted in a lot more and more consistent loft head to toe. Those chambers look about maxed out to me now!
http://www.hammockforums.net/forum/a...1&d=1353442705
But what would be the result if your pod already was already maxed out for loft, if the chambers were already puffed up head to toe as much as the chambers and baffles would allow, and you then stuffed another 20 or 50% of down into those chambers? You can not increase loft, because the chambers are already as puffy as they can get, but you can stuff a lot more down in there. Or like if Stairguy added yet a whole bunch more down to his Pod? Is that going to be warmer? With the same loft but a denser down fill, less air and more down?
Last edited by BillyBob58; 01-15-2013 at 00:17.
Risk, you may want to go back and read the discussion we had about a year ago on this topic for additional thoughts....
http://www.hammockforums.net/forum/s...ad.php?t=44490
Mike
"Life is a Project!"
Stairguy has added 22 oz of down to his PolarPod, and looks like there was plenty of room for it. And from the looks of it, it got them a lot more and more consistent loft head to toe. Those chambers look about maxed out to me now!
http://www.hammockforums.net/forum/a...1&d=1353442705
TY Billybob for the shout out...........I indeed do not consider my Polarpod over stuffed at this point, but it is temperature specific for winter camping in Minnesota which is my favorite season. This does not mean the stock "Polar Pod" is understuffed. The beauty of it is to be able to migrate down to where needed, providing a wind free environment in a multiple of temps. To be honest I have used my stock PP in the basement open vented and comfortable at 78* and w/augmented insulation (clothing and 20* TQ) down to a -7degF
Last edited by stairguy; 01-14-2013 at 19:08.
" Wiggs "
________________________________________
Before I was a hanger, I had acquired a JRB top quilt (horizontal baffles) that was an ounce lighter than specs. Using it on the ground, side sleeping, there was cold coming through the high spots where the down was shifting from the middle of the quilt towards the sides.
Holding the quilt up to the sun, the vacant spaces could easily be seen. Overstuffing made the quilt warmer.
Some manufacturers can slightly overstuff the same sized baffles to achieve lower temp ratings. Maybe there is no benefit from 80% overstuff to 100% overstuff, but you can feel the extra warmth of some overstuffing when contrasted with understuffing of the same shell.
Perhaps the theory and specs of a standard stuffing do not match what happens in long flexible fabric chambers when down is rated by how it fills a wide cylinder with inflexible sides.
Minus 7 with clothing and a 20F TQ? I think that is spectacular! So a stock pod weighs ~ 48 oz, right? And what do two full length 25*F Long quilts with suspension weigh? About 48 oz? I really would love a Polar Pod!
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