Sleeping Mats – Part 2

Ok,

so I did a comparison of 5 non inflatable sleeping mats last week. Some of the criteria were naturally subjective as its a personal thing whether you are comfy or cold etc. If you recall a combination of the scores for the 5 criteria put the Gossamer Gear Thinlight at the top and the OMM duopad at the bottom. I then got to thinking about the warmth of the pads and trying to apply some science and hard data to it.

In line with this thinking and borrowing ideas from BPL, I decided to test how insulative the 5 mats were using a digital thermometer. The idea was to place a mat over the thermometer measuring point, place a foil tin on top of that and then add 250ml of boiling water. Then using a stop watch, record the temperature over 15 second intervals until 90 seconds had elapsed.

I did this for the 5 mats and also for a foil tin without any mat as a control. The results are as follows :

MAT / TIME (sec) 0 15 30 45 60 75 90 ave rise per sec
control (nothing) 23.5 30.2 36.5 40 42.2 43.4 44.2 0.23
Radiator shielding 23.5 27.5 33.7 38.2 41 42.4 43.1 0.22
OMM duo mat 23.4 25.7 27.4 28.7 30.6 32 33.1 0.11
3mm laminate underlay  23.6 26.4 30.2 33.5 35.7 37.4 38.5 0.17
GG thinlight 23.6 25.2 26.6 28.1 29.7 31.1 32.1 0.09
GG torsolite 23.4 24.5 25.5 26.4 27.2 27.9 28.7 0.06

From the above its clear that the radiator material is the worst followed by the laminate flooring material and then the duomat. This is at odds with my perception of warmth. Obviously the measurements I made are based on conductive heat transmission and in this case on high temperatures rather than low but the principle is the same. I was quite surprised at the radiator material being so poor but then it has a reflective surface rather than a insulative material per se. I was even more surprised that the duomat was more insulative than the laminate insulation (which felt very warm).

Anyway, if I substitute the actual results from above into my original scoring matrix, it puts the reflective radiator material as the worst performer. The laminate comes in 4th and the duomat takes third place. The torso pad and thinlight pad remain at 2nd and 1st respectively. This puts the duomat in a new light and although not fabulously comfy it does appear to be a reasonable proposition for use as a sleep mat outside of winter. And of course it does already form part of my OMM rucksack back support.

Science over perception

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About Saddlebags and Backpacks - a brewer's outdoor adventures

I am a keen hiker, camper, cyclist and general all round gear addict..... I also manage to be a professional brewer in my non-spare time :->
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6 Responses to Sleeping Mats – Part 2

  1. Simon says:

    I’m really surprised at those result – or rather, I’m really surprised at the results of the radiator shielding. I use that stuff as my pot cosy (sorry, I’m taking this off topic I know!) and I know it does the job. Although I do have to admit that the outside of the cosy does tend to get quite warm … but that just makes it nicer to hold while eating in the winter.

    • backpackbrewer says:

      Hi Simon,

      me too! Having said that, pot cosy material is reflective on both sides whereas the radiator shielding is only reflective on one side. Just for comparison when I get a minute, I will run the test using a pote cosy (I have one buried somewhere) and see what that gives.

      I am convinced that the pot cosy does a grand job as I use one in the winter without fail

  2. Fascinating couple of posts – I’m sure I’m not alone in saluting your work!

    I wonder if some of the perception vs experimental results puzzle might not be related to the effects of insensible perspiration? I use VBL a lot in winter, and even though the liners themselves have negligible insulating properties (we’re talking bread bags here, after all..) the reduction in heat loss from insensible sweating is quite profound. Perhaps the impermeable radiator lining/laminate provide more of a barrier than, say, the spongier mats do?

    • backpackbrewer says:

      You could have a very valid point there Chris. I am not sure how to capture that in an experiment though! 🙂

      I could go into greater analysis of the reults and compare conductive heat loss versus thickness or weight per volume etc etc

      I still maintain the laminate floor underlay seems to perform reasonably well and at that thickness, doubling up on the material under the torso, for instance, could be a winner.The extra weight penalty would be quite small for the area that loses the most heat (most area/weight in contact with the mat and therefore the ground)

      All I need to do is borrow a few inflatable mats to test out a good range for Part 3 (or Part 1 inflatable if you see what I mean). I have about 5 inflatable mats so thats not too bad to begin with I guess though 😀

  3. Alan says:

    Hi Dave,
    I recently used loft insulation as a sleeping mat, similar to your radiator insulation.
    It is typical bubble wrap sandwiched between two layers of reflective shielding bought from a large DIY store.
    According to the bumf from the DIY shop it is supposed to have the same properties as 50mm of polystyrene.
    I used it at -7/-8 degrees and i was impressed, never felt any cold through it.
    I also have a duo mat but i havn’t tried it on its own at anything less than 0 degrees so i don’t have a comparative comment as yet.
    Also bulk of the tested materials has to be taken into consideration somewhere along the line. I mean we wouldn’t take a 6ft x 2ft x 2” thick sheet of polystyrene with us would we even if it turned out to be incredible insulation.
    I look forward to your next instalment…..Alan

    • backpackbrewer says:

      Hi Alan,

      interestingly enough when I was nosing through some DIY shops recently I noticed that the radiator type reflective shielding is now made with polystyrene. Instead of bubble wrap underneath a foil layer (or sandwiched between 2 foil layers), there is a very thin polystyrene layer bonded to the foil. Amazingly it flexs and rolls quite well and the weight seems to be light too. I may have to get some in the new year purely for research although if it is tougher than I initially suspected it could make it into the pack for a test run

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