Better insulation than down?

[white_monkey]

I started making my own winter clothes a couple of years back and ran across a guy named Jim Phillips (inventor of PALS arctic clothing) who used open-cell polyeurothane foam exclusively for insulating, which works awesome, as it dry's very quickly. I was thinking about shredding up some old foam scraps (very soft) and using that instead of down, for an underquilt; anyone know someone who has done something similar? (I recently made some -40 degree boots with the foam for about 30 bucks, so why not for the hammock?)

[Tedinski]

I'm betting that the insulation value is better, but the weight and compressibility would be just terrible.

How much do the boots weigh?

[warbonnetguy]

yeah, the compressibility would probably be the main issue.

[white_monkey]

The boots weigh a little over 2 pounds total. The foam is 1 1/2" thick and the boots go to the top of my calf. The compressibility of the foam varies with type. I have open cell foam that is very firm and hard to compress and some very soft stuff that practically disappears under pressure. The main benefit (besides being free, since I already have the scrap - a new 8' by 8' by 1" sheet is around $50) is it's inherent ability to move water vapor from hot to cold quickly (the colder it is, the quicker the moisture moves away from the heat source (your body)). I saw a guy wear a suit of this foam who chipped an 18" hole in the ice of a lake in the dead of winter, slip in for 15 minutes, induce hypothermia, get out, squidgie the water off, then get in his foam sleeping bag for bed, and was dry in the morning. He said it was bad because it felt like a steam bath. (He did this on a challenge from some news reporter). Kind of a long tangent, sorry. I think I'll make a 2' by 2' mini quilt and try out the compressibility and weight, to see if it is even feasible. If this works I could save myself a couple hundred bucks...

[oldgringo]

I think I remember a thread on those ocf bags...am I dreaming, or did it happen?

[Rat]

Your not dreaming it did happen, we talked about it alot on that thread.

Interestingly, my brother, a hammock neophyte, has been using open cell foam in his hammock. I didn't even know about it until two weekends ago when we spent a 17°F night on Goodwater Loop. He was nice and warm, which has made me interested in open cell foam as an option. I have never tried it because I thought that it would compress and loose it's rating too quickly, but now I have doubts about that. So I will be testing soon...

The main benefit... is it's inherent ability to move water vapor from hot to cold quickly (the colder it is, the quicker the moisture moves away from the heat source (your body)).

Just for the record...
Water vapor doesn't move from high heat to low heat, it moves from an area of high vapor pressure (High RH%) to an area of low vapor pressure (Low RH%); the temperature has nothing to do with it. Look up Dalton's Law of Partial Pressure.

It is natural to assume that it from a temperature difference since in our cases the bags are warmer than the surrounding air. But in the case of cool temperatures, and we are in our bags, but it is raining (close to 100% RH), the RH% in our bags may be very close to the RH% outside our bags, even though there is a good bit of temperature difference.

I am glad you open cell foam is working so well; makes me more confident in my thinking.

[Mustardman]

The man who makes the foam sleeping bags registered and posted on discussions about his bags here. The impression I came away with was that he had some fundamental flaws in his understanding of how the foam system works, and I'm a physicist so I know a thing or three about physics and thermodynamics in particular.

However, it seems like some testing has shown that the foam systems are effective - IF you are in a situation where it warrants dealing with the extra weight and bulk.



If I were on an arctic expedition with pulks or dog sleds, I would say go for it, but for anything I'm likely to do any time soon, down is the far superior choice, for compressibility and light weight while retaining excellent insulation value.

Your mileage may vary, of course.

[sclittlefield]

The Hennessy Hammock Super Shelter utilizes open cell foam as it's insulation and has had some pretty good reviews here. It's certainly worth trying.

[Mustardman]

The Hennessy Hammock Super Shelter utilizes open cell foam as it's insulation and has had some pretty good reviews here. It's certainly worth trying.

Yeah, as long as you don't mind the bulk of it, it'll certainly be effective. I don't know if I'd call foam "better" than down, though - just a different set of properties that may or may not fit an individual person's needs.

[ringtail-THFKAfood]

The man who makes the foam sleeping bags registered and posted on discussions about his bags here. The impression I came away with was that he had some fundamental flaws in his understanding of how the foam system works, and I'm a physicist so I know a thing or three about physics and thermodynamics in particular.

Does open cell foam = sponge?

I am amazed how material harvested from an aquatic bird is thought to have wet weather performance problems.