Thinsulate?

I made a simple quilt out of it last week as practice really, as it's cheap. Not tested it yet, so not much of use to tell you really sorry. Doesn't seem amazingly warm.

" warmer per a given thickness than down"

Maybe, but 2 inches of down loft will weight slightly less than 2 inches of Thinsulate loft! )

Maybe by a factor of 10?

It's warmer for a given thickness than down or the lofty synthetics, but heavier for a given warmth. So it's great for gloves/mittens or shoes, things where thickness is a problem. Would probably make good booties, since they tend to get squashed while you're wearing them. But for most clothing or sleeping bags, Climashield & Primaloft are superior. The one exception I have heard rumors of is that Thinsulate supposedly passes moisture through more effectively, so if you are using it in a garment that you would put on over other clothing that might be wet (like as a belay jacket), it could have a slight advantage there. But I don't know if that is true or not.

Every synthetic insulation ever invented has been stamped with a claim that it is warmer than down. None of them ever have been warmer per unit weight than high fill power down. According to numbers posted by Richard Nisley, Primaloft One and other high-performing synthetics achieve just over half the insulative value of 800fp down per unit weight. Down is also much more durable.

Despite these shortcomings, I'm working on a pair of long Thinsulate shorts right now. I chose thinsulate because it has near zero water absorption (like Primaloft), so it won't be too badly compromised by wetting if they get splashed during a creek crossing, and because it has low loft (so the garment can be thin).

The Thinsulate insulation is very fragile (more so than other synthetics), but it is sandwiched between two layers of 0.4 oz/yard nonwoven polypropylene gauze. You can (carefully) remove the outer gauze layers if you plan to quilt the insulation between the shell layers of a garment. The outer layers of gauze can be torn easily with a fingernail. They aren't strong enough to serve as a shell material. For my project, I removed the outer gauze layers (saving about 0.8 oz/yard) and quilted the thinsulate between 0.5 oz/yard silk (inner) and 0.67 oz/yard 8D nylon (outer) shell layers. When they are finished they will be heavier and less durable than a comparably warm down garment, but thinner and less sensitive to moisture.

After enjoying the thin draft flap, instead of tube, on a Montbell down spiral bag, decided to use a thinsulate draft flap for the next DYI bag. May leave the gauze in for stiffness.

There is also Thinsulate Liteloft, a totally different product, that has considerable loft and a much better warmth for weight ratio than the regular Thinsulate. It has the very thin olefin fibers for warmth, and larger fibers for loft. OWF stopped selling it way back, because, they said, it was too expensive. Have heard there are loft retention issues with it, but have not had any with a bag I made of it. Plan to use it again for a bag made with .67 oz nylon purchased a while ago on a group buy made through this forum. Will use the Liteloft like down, but with fewer baffles than down, and with the baffles made of very light panty hose material.

Way back when, a friend of mine worked for Moonstone Mountaineering – who in their day made some of the best synthetic bags available. The owner did a test with several types of insulations, making identical bags to compare durability. Polarguard, Liteloft, and Qaullofil were the insulations used. They were used in the field, and repeatedly laundered. The Polarguard won hands down, retaining far more loft that the other two and being warmer per weight even at the start. Since Climashield is esentially the descendant of that Polarguard, and definitely superior, I expect the Liteloft is nowhere near as good as Climashield, particularly as concerns durability and loft retention.

Well, as I suspected, Thinsulate isn't as wounderful as the write-up made it sound. Thanks to all of you for the feedback.

Paul,
Thank you for that info. Will probably mean a change in plan.