Reflective Barriers

[Jsaults]

Would there be a difference?

I have a "standard" laminated Space Blanket with grommeted corners. Are Heatsheets similar to these multi-layer SBs or are they closer to the "emergency" blankets that are packed to the size of a pack of cigarettes?

Jim

[CajunHiker]

Trying to imagine Shug as a shiny spheroid... I suspected as much.

[CajunHiker]

Welcom storrie. I had to go to the Columbia site to read up on this.
I found some videos (some are almost as good as Shugs. Some are WAY better).
http://www.columbia.com/Omni-Heat/Sc...efault,pg.html

So, what would be the most effective way to use omni heat? Would it work on the interior of a base layer?

[Can't Wait]

What ever they said lol

[BillyBob58]

Why not just do a test, one with a vapor barrier and one hammock without. The one who is the warmest and driest would be the "winner" or the one who will make sense of this.
If you are warm and dry and like the system you use,, keep on using that system. If you are old and miserable well then try out a different system,,what ever makes you comfortable,and your stay in the woods enjoyable is all that matters.

These tests have been done. When adding a space blanket ( radiant AND vapor blocking?) to either the HHSS or PeaPod. Sadly, results are inconsistent. Some of us are both warmer and dryer than with no SB under the hammock. Some have been wetter and cold. Some of us have even been " old and miserable".

[Gqgeek81]

I brought up a few of these ideas in my DYI Omni-heat thread. I've been mulling over my previous idea for a few weeks now of trying to use glitter of some sort and I think I have a less messy idea that could do...

Silver tulle fabric!

I imagine its coated much like a mylar SB.
I think its a safe bet it would work to some extent. How much? No idea.
I'm curious to try some tests using it to 'insulate' a warm water bottle or something vs. a control vs. one wrapped in foil.

I think for the blue foam pad used in an SPE a layer of mylar should be a given. Why wouldn't you add a layer for winter use? Its going to add virtually no weight and the blue foam isn't going to breath anyway. Inside the SPE it should be protected from abuse. I bet you could fix it on with spray on adhesive (if it doesn't dissolve the foam) which would keep in place and silent. If its not quite cold enough to need the reflected heat just flip the thing over.

I also noticed Thermarest has such a product out now so someone thought it was worth while.

I think the air gap for reflectix may have something to do with avoiding touching the aluminum to a hot surface which would conduct some heat away. Also, if you have the room for said gap you also get one more dead air space without costing anything extra so why wouldn't you? I don't think they intend to imply the radiative heat blocking properties are dependent on this gap. The real question would be how much is the reflective property reduced by the gap compared to the amount of heat that would be transferred through conduction if the insulation were touching.

In all honestly I'm not sure why we don't see more products offered with a reflective mesh of some sort. I'm not talking about the nanometer scale which would likely take some development, but something closer to Omni-heat.

While it wouldn't be close to the radiating body, I'm curious what would happen if you made one of Sgt. Rock's bug socks with the silver tulle. There's anecdotal reports on the forum that a plain bug net does trap some heat since it does slow the movement of air. What if it was also partially reflective?

[zukiguy]

I've got an older version Thermo-lite bivy taking up space in the bottom of my gear pile. Maybe I can cut out an UQ sized piece to sandwich between it and the hammock bottom for a little more warmth? A few tabs of duct tape and some shockcord loops should make it easy to attach to the UQ to keep it in place. It won't be as efficient as the mylar blanket but a whole lot quieter.

Rather than chop up this bivy though....is there a cheap source of thermo-lite fabric or something similar?

[KerMegan]

Thank you, Spence!!!
So, it sounds like the best place for my IR barrier would be between the layers in my double layered hammock.

Now for the next question. Where can we get a very breathable IR material?

I would sweat to death in almost all conditions with the typical reflective mylars. Maybe should pick some rainy weekend and sit there all day punching a million tiny pin holes in my survival blanket

Ah! But wait! ... remove the thread from my thread injector and just sew rows of holes! Better yet, use my double needle and get done in half the time! ... someone please stop me ... :l

or fold it several times, to increase efficiency?

[nacra533]

I don't see this as a special exception, when you consider the whole picture. Outside the spectral passband implemented by the coating, reflections are actually worsened. By controlling system impedance as a function of frequency, reflections are just shifted by design to occur outside the photographically interesting part of the spectrum. IAE, it's still a passive system and there is no amplification of energy -- just an increased attenuation of the photographically objectionable stuff. In this case, the attenuation is the result of incident energy being reflected back to the source. It's not unlike the design of stub tuned filters for waveguides or coax systems, IIRC.

IMHO, of course... it's been a while since I last had to deal with Mr. Maxwell.

I am a mechanical engineer, so I have to add ....Huh???

I think I know what everyone of those fancy words mean, I just didn't know they were allowed in the same paragraph.


Wouldn't this work better. Me>passive spectral energy reflection thingy (unamplified of course)>hammock>UQ???

[meanmoe]

Radiant barriers, for use in an attic, come in solid and perforated types. They are coated on both sides and are placed either on the attic insulation itself, or stapled to the underside of the rafters. The preferred method is to staple to the rafters as dust build up on the horizontal sheets reduces effectiveness.

The perf'ed variety would be used where the vapor barrier at the interior surface is damaged or minimal (allows water vapor to escape and not be trapped in the cool/cold insulation. ARMA Foil is one brand of this type of radiant barrier. A quick Google search will show both foil and foil/bubble types of barriers.

Water vapor is reason that HHSS space blanket placement is suggested between the hammock and the pad. The SB keeps the water vapor out of the pad, where it would condense. This causes the vapor to travel upward, where it can be vented from under your TQ.