Improving sleeping mat R value.

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!
 

Shewie

Chief Slackpacker
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
 

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.
 

Mole

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

Or in 'warmer' temps radiator insulation 50cm wide
 

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).
 

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.
 

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
 

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.
 

gixer

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.


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
 

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.
 

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.
 

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
 

ADz

Thru Hiker
foil picnic blankets could probably cut in half?

@adz Klymit inertia in your bag on top of your current mat? only 175g.

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.
 

ADz

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.
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


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.
 

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.
 

Teepee

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.

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).
 

ADz

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).


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
 
Top