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View Full Version : Working with primaloft -- temp rating?



JohnG
2005-05-25, 15:03
I'm planning on making quilts (underquilt and overquilt) for use with a HH backpacker asym. I've decided to use synthetic fill for several reasons -- primarily because there are a number of times when I expect that I'll get wet, and down is not so good wet...

I'm planning on using primaloft (unless someone convinces me that polarguard or thinsulate is better), but I can't seem to find any recommendations on how thick of fill I need.

I'm looking for a ~15-20 degree rating on the quilt. Does anyone have a recommendation on how thick to go? Any other considerations I need before working with primaloft? Does primaloft get sewn just like down (baffles and all), or is there a better/easier way to sew with it?

Thanks for the advice.

-john

SGT Rock
2005-05-25, 15:44
Basically you want about 3" of loft then. If an insulation material claims to do it with a lot less, avoid it at all costs. My experiences with Thinsulate and others is they can't deliver on the thinner is better promise.

Just Jeff
2005-05-25, 17:49
I'm looking for a ~15-20 degree rating on the quilt.

Thru-hiker.com sells Primaloft in 1.6" and 0.8"thickness. I wouldn't trust my 1.6" primaloft underquilt 20 degrees, but I sleep cold. I think one layer of 1.6" and a layer of 0.8" on the underquilt (for a total of 2.4"), then a 1.6" top quilt would get you to ~20F. Total loft = 4".

No need for baffles with primaloft...it comes in sheets just like fabric. When you get the shapes cut from all materials, sew it down, finish the edges, then quilt it like on Ray Jardine's quilts. Quilting every 12-18" works on Primaloft...I think that's explained on the thru-hiker site, too.

You'll have to find a way to connect the 0.8" and 1.6" layers (spray glue works), and to connect sections at the edges, where the factory width isn't wide enough, to keep heat from escaping. Overlapping the different thicknesses and spraying them together with glue is one method.

Mutinousdoug
2005-05-25, 18:58
I just finished an underquilt made of Lite-loft (a thinsulite product) using two layers of their THL2 (.8" thick) stuff. Haven't been able to test below 50f for now, but I slept out using only a GI poncho liner for a top quilt and slept fine until the neighborhood dogs decided 4:30am was time to wake everyone up.
I chose the lite-loft over Primaloft for the following:
1) 25% less specified weight per yd equal loft. (incidently, I can't find a single place on the insulation that measures less than 1" thick in the raw state)
2) The Questoutfitters.com site says it doesn't need quilting. I just sewed the edges into the 1.1 oz ripstop all around. Quilting would make stuffing into a sack a little quicker though; I may add some ala Jardin. This way, the two layers shouldn't need to be bonded together like Justjeff describes above.
3) Cheaper than Primaloft. I think I paid $6.95/ yd for the .8" thick stuff, and the actual width was easily 65" although advertised as 60". (not that that saved me anything) The edge was not straight or even, so 60" was probably given as a MINIMUM dimension.
Questoutfitters.com has a page with Primaloft loft recommendations for different temps that seem to agree with what Sgt Rock has given: 3" loft=~20f

peter_pan
2005-05-25, 19:16
Just Jeff, etal,

I'd rethink the top and bottom thickness issues....gravity helps to keep the loft efficient of a gently suspended under quilt...for a 20 degree range 2.5-3 inches is about right synthetic or down....the same is true for the top quilt, 20 degree range should also require minimum of 2.5 inches of insulation. Heat rises so you definately want to trap or slow the loss on top, as much as possible. Thinner insulations can be made to work with the addition of windproof, breathable outer shell/shields much like the use of bivi sacks by ground dwellers....

Many glues break down with moisture...Unless you are sure of the glues properties recommend the "Jardine Tucks" or sew one thickness to one side of shell materiel, sew the other thickness to the opposite side shell...put together, sew borders and finish seams....Make sure you leave 2 inches of uninsulated material on the edges for the seaming or the material will become too thick to created rolled hem seams...Note, this technique is labor intensive as you will have to pin paper over the seams to be sewn on the insulation side....then remove it like a preferated postage stamp before putting the two sides together...use a high stitch count to make lots of preferations...be gentile and use two hands working at 90 degrees to the line of stitch.... Yeah it is a Bi--- to do but works...that is why the "Jadine Tuck" is popular.

Just my 0.02.

Pan

Just Jeff
2005-05-25, 22:06
Thinner insulations can be made to work with the addition of windproof, breathable outer shell/shields much like the use of bivi sacks by ground dwellers....

I was assuming he was using DWR...relatively windproof.


Many glues break down with moisture...

I just meant to keep the insulation layers from sliding during the sewing portion, not for gluing the insulation to the shell material. The quilting would hold it all together when it's complete.

You can probably skip this step and use pins, but that might be tough with 2.5-3" of insulation.


or sew one thickness to one side of shell materiel, sew the other thickness to the opposite side shell...put together, sew borders and finish seams

Sounds like a good idea. I'd still quilt it at the end to keep the insulation from stretching and possibly tearing while stuffing.


be gentile and...

So what do you do if you're Jewish? :biggrin:

Mutinousdoug
2005-05-25, 23:37
"Sounds like a good idea. I'd still quilt it at the end to keep the insulation from stretching and possibly tearing while stuffing."

That's the problem I'm having: Stuffing my quilt into a bag balloons the outer fabric while the lite-loft squeezes into it. Just need to slow down a 30 second job to a 90 second one. Quilting the ends, or putting vent holes there would address the ballooning fabric phenomemon with coated fabrics.
I don't don't know what to do about the Jewish thing, although I'm circumscribed,myself .
Is this OK to talk about on your forum, Top?

Rage in a Cage
2005-05-26, 00:47
So what do you do if you're Jewish?
Use one hand working at 45 degrees :biggrin:

Just Jeff
2005-05-26, 08:29
Quilting the ends, or putting vent holes there would address the ballooning fabric phenomemon with coated fabrics.

People usually quilt the whole bag. Basically, imagine a grid on the quilt with 12-18" squares. At each "cross", you sew a loop with yarn thru the whole quilt, but don't pull it tight. If you want 2" of loft, you put a 2" wide piece of something inside the loop, then pull the yarn tight against it and knot it, forming a 2" loop of yarn. That way, the quilt at that section can never "balloon out" more than 2", but it still won't compress your insulation.

That should be enough to keep the ballooning in check enough to stuff your quilt in a bag. Vent holes would work, too, but I'd worry about them adding to convective heat loss. DWR is relatively windproof, so the heat that's inside the quilt is "trapped" there, even with some wind. If you had a vent, it wouldn't be trapped as well, IMO.

peter_pan
2005-05-26, 08:35
[QUOTE=Just Jeff]I was assuming he was using DWR...relatively windproof.

I assume one uses a DWR fabric also....point is that, an addititional shell, like a bivi, is another way to inexpensively increase range and get more flexibility from a lighter quilt.

I just meant to keep the insulation layers from sliding during the sewing portion, not for gluing the insulation to the shell material. The quilting would hold it all together when it's complete.

Probably still best not to introduce a glue if not necessary...unless the long term effects are known and guarenteed I would not use glue...it may even have some perminent effect on loft.