is it because people don't want to carry a bivy in warm weather?

is it because condensation is a worse problem inside quilts in warm weather?

is it because there is some advantage to its lofting properties over a small amount of down? less quilting required?

i'm basically guessing. i don't really get it because synth is so heavy and doesn't compress very well, making a warm weather quilt ~40% heavier and at least that much bigger compressed.

i'm evaluating my 40*F+ options...

I would guess price and ease of working with factors as well. I use down myself.

I think it's largely because the extra baffling in a down quilt makes the break-even point for loft vs weight somewhere below 40 degrees. If weight is the same, synthetic quilts have the the benefits of being cheaper, more forgiving (moisture/regular washing), and easier to make.

Down is considerably more difficult to work with for a DIY project. Not impossible, and with some care and consideration more than manageable, but never comes close to the ease of working with synthetic insulation.

Then you have the fact that for warm weather quilts you the fabric becomes a much greater proportion of the overall quilt weight. Not the insulation. For VERY rough numbers, assume a ~1oz/square yard fabric (like finished momentum 90). If you have a 36"x72" (2 sqyd) design you end up with 4 oz of fabric (2sqyd*1oz/sqyd*2 sides). Stitching (especially baffles in down quilts) can add around another ounce of weight. So for a basic quilt you're looking at around 5oz just for the shell material. Now if we use down, we probably only need around 1.5" of loft for a 40F summer quilt (using data off thru-hiker's 17oz down quilt instructions). This gives us around 4.5oz of 900fp down.

Now if we wanted to use synthetic insulation we'd use probably a ~2.5oz/sqyd product like Climashield Apex (in fact this is exactly what MLD uses in their 45F spirit quilt).

So for a synthetic warm weather quilt we're looking at around 10 oz (before bells and whistles like velcro) and 9.5oz for down. However down takes considerably more time and effort to construct which most warrant isn't worth the minor weight advantages.

Now for colder weather, quilts use significantly more insulation. The fabric and stitching becomes a smaller percentage of the total weight. This means a more efficient insulation (ie down) now starts to make a noticeable impact on the quilts finished weight. If using 10oz of 900fp down is the same as 15+oz of synthetic insulaiton (probably more synthetic actually), we're looking at finished weights of 15oz for a down quilt and 20+oz for a synthetic. At these weight discrepancies the extra effort of down has a tangible benefit.

This is why you often see down cold weather quilts and synthetic summer quilts in the DIY threads. The synthetic also has a secondary benefit in that warmer weather tends to be moister in most the country (not in my AZ though), so the synthetic provides some poor weather security as well in above freezing temps that down does not have. Not a major concern for many, but a nice perk for being "lazy" during construction of the quilt.

With synthetics you can get away with using non down proof materials like silk. Silk is very inexpensive and light weight. Add a $3 bottle of dye you can make it any color you want. Check out
Thai Silks.

great replies, all! thanks for the info.

another issue is packed size...

Bender - I'm intrigued by using silk as an option. I've had folks wanting gear without having to "peel" nylon/polyester lining during warm weather.

Checked out that site and I'm curious what the description is referring to: Habotai, 8mm, 45". I'm assuming Habotai is the brand, and 45" is the width. Seems like the 8mm can vary from 5mm to 15mm.

Any thoughts?

You have heard of RipStop and Taffeta? They are names for types of weave. Habotai is the name for a light plain-weave silk. It is widely used for all sorts of things, including silk liners for bags and quilts. I make silk PJs out of it as well, for use instead of a liner.

Habotai may come in a small range of weights, but 8 mm is the most common. 8 momme is a fabric weight, a bit like 45 gsm, 1.3 oz or 70 d.

The 45" is the width. It is narrower than most synthetics, because older looms are used.

Cheers

according to wikipedia looks like 1mm= 4.340 g/m^2 so the 5mm would be about .7 oz/yd. Pretty light.

I made a ~ 45 quilt using silk (from Thai Silks) and 2.5 oz Climashield. It comes in around 9 ounces and I love it as my warm weather quilt. As far as the packed size concern: To preserve as much life in the insulation as possible, I pack it in a trash bag loosely in the bottom of my pack and just let everything else pack it down as I load my pack. I've found that since I use this in the summer (when I'm not carrying much extra clothing), I usually have plenty of room in my pack. However, if you're trying to fit it in an Ion or something similar, I'd think down would be the better option.

Note: If you go this route, I would wash the silk before you make all your measurements and do the cutting. I cut it, then washed it, and it shrank a good deal as a result. It still works fine, but it's an easy hang up to avoid.

Edited by amknapp4 on 05/05/2011 19:48:32 MDT.

A Silk lined Synthetic bag sounds awesome. I think you just talked me into my next MYOG project.

Sounds great to me.

i might be sold on silk/synth for summer just as an experiment for my first DIY quilt. we'll see if i find the money for it in june-ish when it's getting warm enough to use it.

Here are several weights for ThaiSilks. The mm stands for momme not millimeter. One momme is 3.543672 grams. I have some samples in 4.5mm and 8mm. The 4.5mm 021H seems tough enough if I'm careful. If the design doesn't require the 54" width I will go with 6mm. I would be using 1.8 oz Primaloft or 2.5 oz Climashield. My goal is under 8 oz since my much warmer Enlightened Down bag is 16 oz. Now I need to find or make a pattern!

For my calculations 1 mm = 3.543672g
4.5mm = 16g
5mm = 17g
6mm = 21g
8mm = 28g

FYI ThaiSilks has 25% off non sale fabrics for Mothers day! This looks like it would apply the Habotai silks we are interested in. For the discount you must ask for the 25% off in the comments box during checkout.

Edited by Bender on 05/05/2011 23:45:40 MDT.

Because Down lumps in to a balls once it get wet is very hard to get back to it natural state.
I have spent to many nights in cold down bags but I like the safety net of synthetic insulation. I also now sleep in a Outdoor research aurora bivy for my shelter.
Terry

cheaper here than thaisilks...
http://www.dharmatrading.com/fabric/silk/habotai.html

Has anyone used the 5mm habotai for any projects? I am wondering about durability compared to the 8mm silk.

White 5mm silk was what I used for a sleeping bag liner. It is OK, as long as you keep your toenails trimmed.

--B.G.--

Bill's thread is the inspiration for my project. He used 4.5 mm silk and 2.16 oz insulation for a finished weight of 8.76 oz. I will be using 4.5 mm silk and 2.5 oz Apex. I'll have to play with the numbers to see what the estimated weight will be.

@Bender, what approx rating are you going for? i know about the loft numbers for down, is there something similar for the synth materials?