Improving sleeping mat R value.

Discussion in 'Sleep Mats' started by liamarchie, Nov 19, 2016.

  1. liamarchie

    liamarchie Ultralighter

    I have a synmat hyperlite with a value of 3.3 which doesn't quite cut it when it's getting frosty.

    How do you increase the value without buying a whole new pad to replace it?

    Either something like a Ridge rest at 400g, or a cheap foil ground mat thingy for about 100g

    Any one have any experience doing this and advise what they found most effective for the weight? Any other suggestions would be welcome too!
  2. Shewie

    Shewie Administrator Staff Member

    Teepee of this parish uses one of those silver backed foam windscreen protectors to boost his inflatable.
    Very light and seems to fold up okay
  3. Robin

    Robin Moderator Staff Member

  4. edh

    edh Thru Hiker

    I've used a silvered survival blanket; OK - but probably not in winter.

    In a similar manner to Robin have also used a GG Thinlite - surprising difference in temperature noticed.
  5. Mole

    Mole Thru Hiker

    I use 3mm ccf like Robin linked to. 75cm wide x 2 m

    Or in 'warmer' temps radiator insulation 50cm wide
  6. Enzo

    Enzo Thru Hiker

  7. Robin

    Robin Moderator Staff Member

    I use it all year round. Winter with a full length Thermarest XLite. Rest of year with XLite short. Also gives me peace of mind if air mat fails as you can just about sleep on it on its own (which I did once).
  8. Imperial Dave

    Imperial Dave Section Hiker

    as per Ed, GG thinlite is awesome. Have even used it on its own in winter
    Whiteburn likes this.
  9. fluffkitten

    fluffkitten Moderator Staff Member

    A shiny ground sheet from Tread Lite works well with inflatables.
    Robin likes this.
  10. el manana

    el manana Thru Hiker

  11. el manana

    el manana Thru Hiker

    Last edited: Nov 19, 2016
  12. Teepee

    Teepee Thru Hiker

    I use the foam that Enzo linked to above, have done for years. 60g for each 60 x 180cm sheet, 70g with the Tyvek edging stitched on.

    Thinlight is also very good.
  13. Jamess

    Jamess Section Hiker

    +1 for radiator insulation.

    I can get circa 20 nights from a piece before it needs replacing.
  14. Enzo

    Enzo Thru Hiker

    I was thinking of spray glueing a layer of polycryo on the aluminised foam to help protect from spikey stuff, I use a multimat superlite air so 20d and presumably quite vulnerable.
    P . s I think for best ir reflection the aluminised stuff should go under the air mat and any ccf mat on top, much nicer to sleep on than air pad with a quilt too
  15. FOX160

    FOX160 Thru Hiker

    Might as well use Bacon foil which would reflect has much heat as anything else and lighter!
  16. Rog Tallbloke

    Rog Tallbloke Thru Hiker

    "Reflecting heat" is a bit of a fallacy so far as campers are concerned. Conduction and convection are much bigger heat transfer issues than what will be re-radiated by a reflective surface.

    Fizzics innit.

    The main value of silvered surfaces is they tend to be on waterproof substrates. Fragile substrates in the case of the silver backed foam "picnic blankets" Enzo and Teepee are referring to.
  17. gixer

    gixer Thru Hiker

    Aye, the problem is if you don't have insulation then that silver foil is just going to act like a great heatsink.

    For laying in the ground insulation is better than any sort of heat reflection i recon
  18. Rog Tallbloke

    Rog Tallbloke Thru Hiker

    A sheet of thick corrugated cardboard and some plastic sheet to keep it dry is perfectly good, if a little heavy/bulky. Makes a great packframe too.
  19. Teepee

    Teepee Thru Hiker

    Whilst radiated IR radiation does usually make up the smallest fraction of heat lost to the environment, it's not usually a negligable amount.

    Anyone with a Exped Downmat can feel the effect for themselves by sleeping on the wrong side. It's noticably colder, due to a reflective layer laminated to the sleeping side.
    kiltedpict and gixer like this.
  20. Rog Tallbloke

    Rog Tallbloke Thru Hiker

    An exped down mat is more noticeably colder at one end if you hold it vertical before laying it in your tent and all the convection preventing down falls to one end. But I agree it's not negligible. I also use one of the silvered 'picnic mats'. Still reckon the 2mm of foam does more for me than the silvering though.

    The cardboard mat also works well as emergency firelighter. :D
    WilliamC and Teepee like this.
  21. ADz

    ADz Thru Hiker

    I sold that mat bud, as per link.

    I currently use a small NeoAir Xlite combined with foil blanket. I have other ways to augment though like thin CCF pads or a foil covered pad like car windshield reflectors etc . I can't really ever remember my legs/feet getting cold on any trip regardless of system so decided to go back to smaller mats for bit to save some grams. Always have my Zseat with me anyway so if needed that can act as padding under legs.
  22. ADz

    ADz Thru Hiker

    To be fair I don't think the use of silver foil under a sleeping mat is about reflecting heat. It's more to do with reflecting the cold (Or creating barrier) from the ground away from you. If it was about reflecting heat you would use the foil on top of you, not under.
  23. Rog Tallbloke

    Rog Tallbloke Thru Hiker

    The amount of energy lost as radiation from the outside of your sleeping bag is proportional to its surface temperature. It going to be warmer under you where it is compressed than above you where it is lofted. Some of that radiated energy will be reflected back to your sleeping bag by a silvered surface under you. The main value in a silvered surface above you would be the degree to which it inhibited convection and conduction of body heat to the cold air above. This will be a bigger part of what laying a space blanket over will do for you than the reflection of radiated heat. But an impermeable silvered surface above you will form condensation on the underside, which if bad enough, will dampen your sleeping bag and reduce it's loft, losing you more than you'll gain from it.
  24. Teepee

    Teepee Thru Hiker

    It helps to think about an aluminized reflective layer as a normal mirror, and radiated Infra red(heat) being visible light.

    If you shine a torch at a mirror in an unlit completely dark room, it will reflect that light (Infra red) . Turn the torch off, no light will be reflected.

    It's impossible to reflect nothing (cold/torch off), only something can be reflected (IR/torch on).
    Meadows, JKM and ADz like this.
  25. ADz

    ADz Thru Hiker

    I understand that bud. But surely your insulation touching cold surface would potentially lower temp of insulation (mat/bag etc) and thus make it less effective? In that context surely a foil lined blanket would protect in some way? Or am I thinking/processing this all wrong because of hangover/lack of sleep again :D

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