insulating with foam sheets

[Migrating Bird]

All this discussion has me thinking "fish net stockings". I apologize as I am not only new to hanging but not very sophisticated as well.

[matto]

Maybe something like the "Astro Foam Sleeve"?

I've only ever seen these in asian supermarkets -- usually on the asian pears -- but maybe there's a way to source whole sheets of it. Either that or order a gross of the sleeves and get out the scissors and glue.

[pedro]

Maybe something like the "Astro Foam Sleeve"?

I've only ever seen these in asian supermarkets -- usually on the asian pears -- but maybe there's a way to source whole sheets of it. Either that or order a gross of the sleeves and get out the scissors and glue.

Good thinking! How about taking EVA headliner foam and punching a diamond pattern in it?

[Albert Skye]

What thickness of foam sheet are you thinking of expanding 1/8"?

1" O.D. leather punch will work. Affix it to a hammer handle and whack away.

I would think slits would just compress sideways

I like expanded mesh because it makes zero waste. I've not converged on any specific dimensions yet. Much depends on the properties of the material and the dimensions of the slits.

Another method is to make a simple net of narrow, twisted strips (i.e., the twisting yields an effective diameter similar to the width of the strip, reduces the tendency to flatten, and reduces conductive thermal loss).

[Stovemandan]

I have some working knowledge of greenhouse insulation using air gap between layers of panes of glass. A minmum gap of 1/2 inch is recommended and 3/4" is ideal.

Should we apply those dimensions in regards to insulation with foam sheets? I say, yes. Use 1/2" high density foam sheet and perforate with 1" diameter leather punch or hole saw. Holes staggered, 1" apart to prevent collapse of air space.

http://en.wikipedia.org/wiki/Insulated_glazing

Thermal performance

The maximum insulating efficiency of a standard IGU is determined by the thickness of the space containing the gas or vacuum. Too little space between the panes of glass results in conductive heat loss between the panes (the inside surface of one pane cools the surface of the other pane) while too wide a gap results in convection current losses (gas begins to circulate because of temperature differences and transfers heat between the panes). For further information, see the article heat flow. Typically, most sealed units achieve maximum insulating values using a gas space of between 5/8 to 3/4” (16–19 mm) when measured at the centre of the IGU. When combined with the thickness of the glass panes being used, this can result in an overall thickness of the IGU of between 7/8 and 1” for 3 mm glass (22–25 mm) to 1½” (28–31 mm ) for 1/4” plate glass.

[turnerminator]

Maybe something like the "Astro Foam Sleeve"?

I've only ever seen these in asian supermarkets -- usually on the asian pears -- but maybe there's a way to source whole sheets of it. Either that or order a gross of the sleeves and get out the scissors and glue.

Ive seen plates and mugs wrapped in this same stuff from department stores. Its been in sheet form, not tubes.

[Albert Skye]

A minmum gap of 1/2 inch is recommended and 3/4" is ideal.

A 3/4" gap may give better performance than a smaller one but foam is a much better insulator than glass. Also, I imagine gravity (i.e., vertical rather than horizontal orientation) informs those dimensions.

I'm operating under the assumption (based on discussions about Insultex) that the foam is providing an insulated membrane and the primary purpose of separating the layers is to reduce conductive heat loss through direct contact of the layers. I imagine the separation distance between layers increases in significance with the thermal conductivity of the membrane; i.e., with insulated membranes, even the slightest air gap gives good results.

A very thick separation layer would add significant weight and volume; I think it's better to use down or inflation if one needs that much loft. However, my aim is to use differential construction to support a larger gap than the separation layer, which is essentially a backup for areas where the two layers would otherwise come together.

[Hamper]

I hope this isn't too far off topic, but this thread brought up some questions that my feeble little mind couldn't answer by reading the multitude of threads on Insultex.

I'm thinking of getting a Claytor JH. I like the double layer feature to hold a sleeping pad, but I was wondering if I could also just put some Insultex between the layers. This thread makes it seem like I would have to make sure there were multiple layers and some kind of separation of those layers. Is this a viable option for three season bottom insulation?

If it works, couldn't I just keep the Insultex layers inside the sleeve even when I pack the hammock, making a separate stuff sack unnecessary?

Would Insultex do anything for me if, heaven forbid, I ever had to go to the ground in bivy mode? I'm sure it wouldn't give me as much comfort padding wise, but would it still keep my fanny warm(ish)?

Is there any way to buy small amounts of the stuff to try it out? If so, where can I get it?

Thanks!

[Stovemandan]

Using a separate layer of expanded mesh made from foam sheet seems promising. It's labour-intensive (though easily tooled once the dimensions are optimised) but I think it would work well.

Alternatively, the layers could be separated with a replaceable air bladder (plastic bag), .

Your original idea will work the best.

[phatpenguin]

Thinking air bladder, what about something like this http://www.balloonbed.com/

you could make the channels fairly broad so you only need a few balloons. The problem with this setup in the past is that you have to have lots of balloons since they actually provide the insolative layer as well and they are not great insulators, but if you used ix as the two outer layers you could get away with fewer balloons. If like me you can blow them up without a pump, then it is even lighter. I would start with 260s instead of 350s since I think the large width is not as important here as if you were laying on the ground. Since they use 7 balloons in a full pad I would guess you could get away with 3. Hey Mac, you got a few yds. of insultex for sale, I may have to try this.