Infrared views of sleeping pad insulation

I enjoyed that, thanks for sharing. He does a good job highlighting the area where heat is essentially flowing straight through the pads, but did not  seem to touch much on the relative size/area on each pad where heat was coming through. This is going to have a much larger effect than max temp in the grand scheme of heat loss. It would be so cool if he was able to take a birds eye shot of each so one could reasonably compare the areas of heat loss. This would be especially useful for someone wanting to do a hack, like say, adding some trimmed foam over the sections of a given pad, knowing where the heat is “leaking” from.

Also, I wish he would’ve test the x-lite as well, since many people seem to ask about choosing between the x-lite and the xtherm.

I think he should have had the pads the other way up to better simulate heat flow through the pads. I’m pretty sure that many of the insulated pads have a top side where the insulation is placed closer to the user.

That was a great overview of sleeping pads for people who like to watch videos instead of reading review articles.  Like Michael said, it would have been nice to include the NeoAir X-Lite because I feel it’s still a very popular pad.   However, you’ll never satisfy everyone in a review like this.  I’m sure others would have liked to see at least one pad from Big Agnes or Exped, so it is what it is.

I think he should have had the pads the other way up to better simulate heat flow through the pads. I’m pretty sure that many of the insulated pads have a top side where the insulation is placed closer to the user.

I don’t think these pads are thermal diodes, but some of them do behave differently if you turn them upside down.  Some I’ve seen have the insulation glued to one surface and rely on gravity to fluff it up by pulling it downward.  So I think turning the pads over would have been a bad idea.

If I were picking nits about his methodology, I’d first point out that focusing on the hot spots down in the valleys between tubes might not be right.  In a real application, the camper’s body would span from tube to tube, creating a trapped air space that arguably would mitigate at least a little of the hot spot.  Maybe he should have laid a stiff piece of cloth across the top of the pads?

Also, he did an experiment showing that the thermal mass of at least two of the pads differed, changing the time to equilibration by what, 30 seconds?  So I think two minutes was insufficient as a warmup time before shooting his pictures.  Should have been 5 minutes or maybe 10?

“So I think two minutes was insufficient as a warmup time before shooting his pictures.  Should have been 5 minutes or maybe 10?”

If that is the case, than that makes me wonder:

If I am burning energy to “warm up” my pad to an optimum state before it performs to it’s optimum level, then is that energy expenditure figured in ASTM R value calculations?

Because I’m absolutely certain closed celled foam doesn’t need to be warmed up in order to resist heat flow.

Either way, very cool video and glad he used the thermal imager. For years, I’ve been mulling around how to measure mattresses using an older version of one of these. Was thinking of setting up a mattress over a big sheet of shower glass and having one of my kids climb on top of it.

If I am burning energy to “warm up” my pad to an optimum state before it performs to it’s optimum level, then is that energy expenditure figured in ASTM R value calculations?

Because I’m absolutely certain closed celled foam doesn’t need to be warmed up in order to resist heat flow.

I may be misinterpreting @texasbb’s comment but I understood it to mean that pads with a higher R number will take more time for the heat to start passing from one side to the other, so more time is needed before looking at the amount of heat emitted.

There is information to be gained by the IR images, without a doubt. The air mattress with the highest R value (via ASTM test) clearly shows the best performance. But not quantifiable.  Until the top and bottom surfaces reach a constant temperature, the temperature readings are not reliable.  From what we watched, we simply cannot know if or when steady state might occur.   Testing standards typically require that steady state by achieved and then maintained for a period of time before starting the test. The most critical issue missing in this type of test is the following: These air mattresses rely on air, internal baffling and in some cases, synthetic insulation for warmth.  When a body is on the mattress these features compress and dimensions change.   Their thermal performance will become very different from that of an unloaded mattress. The heat loss at the seams likely changes because all of the spatial relationship of physical features change when subject to compression from a body. That is why the ASTM test uses a heated mannikin. The mannikin will replicate typical body dimensions and weight. The mannikin is instrumented to track the energy lost through the sleeping bag during the test.  The temperature above and below the bag is maintained at specified levels to provide a useful temperature difference.  The impact of design differences such as the width of seams is baked into the test results.  I don’t have the standard to review, but you can be certain the test does not start until the heat loss from the thermal mannikin reaches steady state.  This eliminates the question of how long the test run to achieve steady state.  If the test is administered by a reliable 3rd party lab and the test reports are made available to the consumer to eliminate possible manufacturer’s testing shenanigans (perhaps wishful thinking), I would rely on those numbers for assessing thermal performance.  A couple of the mattresses in the review are not subject to the ASTM test.  I would ignore any of the manufacturer’s claims about thermal performance for mattresses that have not gone through the ASTM test.  After all, how can they know? The mannikin set up is the way to go if you have the resources (money and expertise) for such a testing procedure.

I may be misinterpreting @texasbb’s comment but I understood it to mean that pads with a higher R number will take more time for the heat to start passing from one side to the other, so more time is needed before looking at the amount of heat emitted.

Exactly.  You expect the R-value to make a difference in how long it takes the top surface temperature to stabilize after laying the pad on the heater, which is the main point.  I alluded to the filmmaker’s Forearm Heat Dissipation Test because it may show that the time constant here requires more than a couple minutes for equilibration.  (Or it may show nothing at all, but regardless, you want the surface temperatures stable before shooting the pictures.)

And I agree with @crashedagain about the effects of compressing the pad with a human, etc., but we can only expect so much of a garage setup like this.

“That is why the ASTM test uses a heated mannikin”

Hi Stephen,

While I understand the ASTM test for sleeping bags uses a heated mannikin, ASTM F3340 (the sleeping pad test) uses a guarded hot plate apparatus, not a heated mannikin. For air mattresses, it averages the results from three evenly spaced locations on three mattress samples.

The images shown for the Klymit V pads explain my experience. I’ve found those pads almost unusable with a quilt. But they work well with a bag, where the insulation on the bottom of the bag fills up those deep Vs – as the designers intended – and provides insulation where the pad does not.

Matt:  You are correct.  I was confusing the ISO sleeping bag standard.  This is totally different.  I will receive the standard shortly and review it.  But, it uses a hot plate/cold plate configuration and the hot plate, on top, is applied under pressure to simulate the weight of a sleeper.  I will provide more details once the standard arrives this evening.  Sorry for the confusion.

I think the comments here are a bit beyond what the intended scope of the video were intended to report on.

The video does not provide any objectively valuable data. He gives max observed temps, but they are only valuable in that they are being compared to other mats in a similar environment. You could argue that the 3D printer bed adding heat to the garage over time would skew the results of the pads tested later compared to those tested earlier, since there will now technically be a smaller temperature differential between top and bottom of the pad as the garage warms up. That will also result in higher registered max temps for the later pads. This may explain if the Xtherm was tested last, why there was a higher registered temp than expected for such a high R-value.

This was a good comparative test for people wanting to see the differences between different pads looking from a very high level.

I am not familiar with the spec and test methodology used to measure R-values in a lab – I would hope and expect they reflect the intentions of those who defined the standard, namely sleeping pad manufacturers who want to be able to honestly show they have made a superior product for their target demographics. This video showed some interesting stuff, even if it wasn’t standardized. Humans are not standardized; anyone with reasonable expectations can have a look at these different pads and from this video get a general idea of what they are looking to buy.

The pads may not be thermal diodes but if there is a greater air space on the lower side than on the side closest to the sleeper it could affect the rate the pad heats up due to internal convection currents and does the reflective layer inside the xterm work equally well from both directions?

From a heat transfer perspective, as long as each pad was tested the same way (which it looks like they were), then the comparisons are valid. Again, there is no way anyone can come away from this video knowing whether a pad will keep them comfortable unless they own one of these pads already, so they have a reference point. Without a reference point, all one can take away from this video is relative warmth, and the general area where each pad is giving up warmth.

->The ETHER LITE at R3.2 is identical to my REI FLASH insulated 3 season mattress.

->identical inflation/deflation valves

->the REI FLASH uses a StS inflation bag

->nearly identical quilting pattern

->both have synthetic fiber insulation and a reflective layer

-> at 15 oz. (Regular size) the FLASH is a bit lighter than teh StS bur also a bit thinner

“A (StS) pad by any other name…”

I like the FLASH 3 season so much I got the REI FLASH All Season R5.2 winter mattress.