Ideal Maximum compression of Synthetic wares…

OK, since no one wants to answer my original question, I’ll ask it differently.

How much *volume* of insulation is used in a Cocoon Pullover? Cocoon Pants?

Ryan mentions he puts his pullover in a 250ci SS and both garments together in a 500ci SS. So, if I can get the insulation volume of these garments, I can back my way into the answer I’m looking for.

Hi Tony,

I don’t have any quantitative figures to give you, but I’ve heard that if you have to use force to stuff an insulated item into a SS then you’re probably damaging the loft. Stuffing should require very little force.

Besides, stuffing the heck out of things doesn’t really help them fit into your pack. If you stuff loosely, the item will be able to conform to the contours of your pack better and you can always compress it more after it’s in the pack. This is discussed in “The Backpacker’s handbook IV”.

That’s what I have assumed, but unfortunately, I’m trying to figure out how large of a stuff sack to make (or buy) for a particular item. And, in a round about way, determining pack volume required when carrying partiular gear.

Given Ryan’s examples, I can easily see how large of a SS to use for a similar size insulated jacket, or pants. But for larger items like a 3D quilt for winter camping, I don’t have any “respected” metrics to base on.

When trying to ascertain correct stuff sack size I tend to ‘eyeball it.’ Of course this isn’t very scientific, but generally seems to work. I approximate which sack might work for which item(s) and then give it a try. If the item is too ‘hard’ to stuff then I size up and the opposite if the sack is too big. I do end up with a few extra sacks but that makes sizing items in the future easier.

There are a variety of lightweight stuff sacks out there. Because of this there are many sacks that are slightly different in volume/dimensions making it easier to ‘tweak’ and find just the right volume/dimensions.

Tony,
One way to go about this is to just make one, try it, and if it is too large or too small, try again. You can never have too many stuff sacks, and they are quick to make. So you may end up with a good supply before you get it right. But that is all to the good.

As to how much to compress, as little as possible is always a good rule with any insulation. Don’t obsess on x or y cc’s, just do it.

Tony,

this is a bit late. i can’t personally answer your question. however, i think the Jacks R’ Better website might give some insight.

i realize they are talking “down” here, and you mentioned synthetics. just see what you can figure out from their website and take some “reduction”, so to speak, for synthetics vs. down – 15% less, 20% less, 30% less, 50% less??? i sure don’t know.

[Caveat: they do mention “compression sack”. so, not sure if you really want to compress and go that small. i’ve read that’s bad, i.e. compression. but i gotta believe that these guys know what they are doing. however, having said that, personally, i wouldn’t compress – err on the side of caution. it’s up to you, i guess.]

go to their website’s product page. scroll the page down and click on their “Quilt” links. while they don’t seem to mention how much down (unless i missed it) is in each quilt, they do give the dimensions of both the quilt fluffed and lofted, and when stowed in its compression sack. so, you can calculate cu. in. of both and the compression ratio. do that for two or three of their quilts.

if you can find a website that gives similar figures for synthetic bags or quilts, that would give you a closer approx. ratio for your purposes. i, personally, can’t remember a website that gives these numbers however.

not sure if it would be more accurate to use oz. of down and its fill power to calc. “stuffing”/compression, or the overall dimensions of the fully fluffed and lofted Quilt/bag/down-filled-object”. perhaps, the second since the outer fabric is an integral part of the whole process/calculation.

since JrB only give dimensions of their quilts and the max. recommended compression sack, this is all you can use.

at any rate, you only want an approx. guide and not a precise to two decimal places number. plus outer fabrics will probably change the overall compression ratio, i guess?

just keep in mind that the ratios Jacks R Better obtains will differ for your gear depending upon type of insulation and type/weight of the outer fabric. but then, i believe you already know that. i only mention it for any newer readers who may not be as experienced as you seem to be.

so, without further ado, here’s the link:

Jacks R Better – product webpage link – click me!

if anyone out there can add in dimensions (stuffed AND unstuffed) for their synthetics, that would help.

until then, perhaps, these number can give some starting point? just take a logical, conservative reduction from the down. again, don’t know what that would be.

i’ll also hunt around for a website that gives similar stuffed/unstuffed dimensions for synthetic bags and quilts. i’ll post back if i find any.

I thought about doing this, but I can’t get a handle on what the down vs Synthetic ratio would be as I don’t own any synthetic insulation items at this time.

And I certainly don’t want to make 5 SS just to figure out the appropreiate volume. I already have too many. But those are way too small to use as a test case for something large like a synthetic bag.

I was really hoping Ryan would respond. Seems like the kind of geeky information he’d know. Maybe I’ll bait him with a few “Herein’s”.

Herein. Herein. Herein.

That ought to draw the Doctor closer.

Tony,

i have been checking some websites, but nothing yet on synthetic compression. sorry. i’ll keep looking.

Tony,

the following link to Moontrail has both down AND synthetic bags. while, at least on the ones i checked, dimensions of the bag weren’t given, type and wt of the fill was, as well as type of the fabric used and the size of the bag when stuffed.

you might want to use this data to “build” a table, or series of tables based upon Temp. rating, fill type, outer/lining fabrics. after seeing this data tabularized, something may jump out at you. at least, you can use it to perhaps interpolate and figure out where your gear would fit in. you can calculate compression ratios based upon fill wt, temp range (???-may not be necessary to “break down” the bags this way), and fabric types since the dimensions of the stuffed bag is given. perhaps an approximation like this is close enough for “gov’t work”, so to speak.

when you have some spare time, check it out and see if the data there can be applied to your bag(s).

i don’t think you will any difficulty, but if, just by chance, you do, Post back and i’ll try to tabularize the data for several of the bags in an XL spreadsheet. i could then email it to you and you can use it as a guide to add other bags’ data into it. obviously, if Dr. J (or someone else) posts back with some hard “numbers”, then the exercise i proposed is unnecessary.

heres the link to Moontrail – sleeping bags

p.s.
i’ve purchased several times from them. very responsive company.

That just might work. For example…

Bag: Moonstone Delta Minima (PGD)
Fill weight: 19oz
SS Size (I assume this is the manufacture sized SS): 9.5″ (dia?) x 15.5″

So, if I would find the density of PGD, I could determine the volume of PGD in this particular bag and from that determine the manufacture’s (?) suggested maximum compression.

Happen to know the density of PGD?

sorry. i don’t. maybe someone out there does. you might also check the mfr of 3D and Delta website. i usually just put the mfr. name in Yahoo’s search box and one of the “hits” is to the corporate website. often good info there – did this recently for someone from “down-under”. in that case it was the Pertex website.

BTW, who makes 3D and Delta? is Polarguard the name of the company?

i think that you are right. based upon how my synth. bags stuff, i would guess that the smaller # is the dia., & the larger # is the ht. the only bags i’ve seen with the dim. opp, i.e. the larger # being the dia., were large, heavy, inexpensive “camp” (not backpacking) bags.

keep in mind heavier outer fabrics will cause the bag to “stuff” larger. so compare the outer & lining fabrics fo the Moonstone to your fabrics.

good luck.

this just in.

link to Polarguard website – i haven’t checked it out too deeply yet, so i don’t know how much technical info and specs are there

you might try to contact them if you can’t find the info you require on their website.

The Air Force has rejected synthetic insulation for their survival kit bags because they wouldn’t rebound enough after compression. The kit fits under the ejection seat. They would only consider down, the only synthetic insulation that passed their test was hoechst celanese’s lamilite.Quallofill, Polar Guard,Hollofill, all quilted or chopped stapled fills just shouldn’t not be taken to the extreme of compression.Don’t push them and they work fine,I had to ruin 2 bags before I figured this out here in the rainy northwest. These things make very expensive dog beds…

Larry,

good info. thanks for posting.

i think Tony already knew that the insulation could be damaged by compression. perhaps i misunderstood him, but i thought that was the whole point of his question, viz. how much could he stuff/compress without running the risk of degrading the insulation.

also, if i understood it correctly, it appears the PG website would try to lead one to believe that substantial restoration of loft is acheivable after compression, but they don’t give too much in the way of specifics (some numbers, but not enough detail). their column charts might be a little misleading. i think we all know that this may be a lot of marketing hype.

thanks again. appreciate the info you provided.

I think I’ll give the guys at Integral Designs a call/email. I bet they’d help me out.

I don’t have exact number, but I did discover that ACYE has the density of PL1 listed on his site (0.00384 oz/ci). So, using the sample bag above (assuming PGD and PL1 have similar densities), I get 19oz / 0.00384 == 5000ci of PGD. Stuffed into 1100ci stuff sack or a 78% reduction in size. Being a bit more conservative, 70% compression seems like a good round number to work with.

Using my mythical (way too large) quilt mentioned in the first post, the 8600ci quilt should be placed into a SS no smaller than 8600*.3 = 2500 ci. Damn that’s big. Of course, so is a 6’x4′ bag.<g>

Tony,

good research. thanks for posting the results of it. in the future, if you have any updates, please post them. many thanks.