Therm-a-Rest ProLite Air Mat Product Review

Cascade Designs upgraded their ProLite self-inflating mat once again, with another weight reduction. What were the consequences of weight loss on warmth?

Recommended

Overall Rating: Recommended

The mat is well-made, lighter than most of the equivalent competition, is comfortable, warm enough when not on snow, and seems quite robust. However the bottom surface slides around on silnylon something awful. For the user to fix this with some stripes of silicone sealant is simple, and Cascade Designs should have done so themselves.

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by Roger Caffin |

Technical Details

Therm-a-Rest ProLite 3 Air Mat Product Review - 1
Photo courtesy Cascade Designs.

Alan Dixon reviewed the Therm-a-Rest ProLite 3 back in 2004, when he noted that 'Cascade Designs has whacked more than a quarter pound off their lightest sleeping pad.' The weight for the Small or 3/4 length mat had been reduced to 370 g (13 oz) at that stage. Well, they have reduced the weight even further: the Small (3/4) is now down to 310 g (11 oz). This is getting rather light.

In the process the claimed R-value has dropped a bit, from 2.3 down to 2.2, while the thickness has stayed the same at a nominal 25 mm (1 in). The R-value is going to vary a bit depending on what pressure you put into the mat. This is discussed further under 'R-value.' The nominal length and width dimensions have stayed the same at 505 x 1200 mm (20 x 47 in), ignoring the welded edges. Note however that the mat tapers at the bottom end, down to about 380 mm (15 in).

The foam inside is urethane - as usual with any decent air mat, and the fabric is nylon top and bottom. Both top and bottom surfaces are covered in lots of little dots of something (maybe polyurethane again). The web site says 'Rest Comfortably: Bottom grips and textured top surface hold the mattress in place while you sleep.' This apparently refers to the little dots, but see below for further comment on this.

Therm-a-Rest ProLite 3 Air Mat Product Review - 2
Camp below Matte, Via Alpina, Switzerland.

The foam has had star-shaped holes die-cut out of it to reduce the weight. These holes are visible when the mat is inflated, as you can see here. It is interesting to see that Cascade Designs have chosen the more expensive path of only selectively cutting these holes across the mat. That is, rather than taking a long slab of foam and feeding it through some sort of mass-hole-punching system, they have only cut the holes in the middle of the mat. They have left an unpunched edge down each side and across the bottom and a larger unpunched area at the top end where your head goes. You can see the unpunched edges here too. These unpunched areas are meant to provide extra support at the edges and under your head.

Field Testing

As a background to this I should explain that my wife and I have in the past each used a 3/4 length Therm-a-Rest Deluxe LE mat, which has a very nice soft fabric surface and is about 50 mm (2 in) thick. These have been faithful companions for many years and on many ski-touring trips. Sadly, they are no longer made. The only trouble with them was the weight - 750 gm (26 oz). Some of that high weight was due to the coring used: longitudinal holes. That design did however make the mats quite warm in the snow.

Therm-a-Rest ProLite 3 Air Mat Product Review - 3
Camp at the foot of Glacier de Moiry, Chamonix to Zermatt, Switzerland.

We wanted to reduce our pack weights some more and reluctantly accepted that we needed lighter air mats. The weight of the new ProLite mats was good, but would they be warm enough and soft enough? We took the plunge, got the mats, and set off to Switzerland for another two months walking. The verdict was that they were fine.

I had better qualify that verdict. The mats were normally used on alpine snow grass, as shown here. This can be fairly soft in itself, and does provide some insulation from the ground. Mind you, the water in that tarn was cold!

How are they inflated? Like all good foam-filled air mats, you unroll the mat and open the valve. Go away for a few minutes, and they will self-inflate - up to a point. Typically my wife looks after this while I am looking after the tent: when they seem to have reached equilibrium she gives them about three large puffs and does up the valve. I imagine that over time the puffs might put some moisture into the mats, but we haven't noticed any problems. We always store the mats on their sides inside the house with the valves open when not in use, and I think (hope) that they dry out a bit during storage.

Therm-a-Rest ProLite 3 Air Mat Product Review - 4
Evening at Mumbedah Creek, Kanangra-Boyd NP, Australia.

While my wife likes her mat fairly firm, I often let a tiny bit of air out of mine. Doing so lets my hip get closer to the ground, but if I am not sleeping on snow that doesn't worry me. But the slight reduction in pressure does significantly increase my perception of comfort.

We normally tie our two mats together so we don't get a gap in between. This is good for those cold nights when we supplement the warmth of our UL quilts by snuggling up together. (Hiking with your wife has some advantages!) The photo here shows one of the blue tie straps just to the right of my wife - it was a mid-summer warm evening. However, while this works excellently with the parallel-sided Deluxe LE mats, it is a bit more tricky with the tapered ProLite  mats. The end result is that the foot end of the mats are close together but the foot end is narrower. Well, true, but the narrowness is not a real problem, given the significant weight-reduction.

I had better also add that these are only 3/4 length. I cover the rest of our tent floor with some 5 mm EVA-30 foam. That protects the silnylon floor of the tent and provides just a bit of insulation under my feet. The combination is generally enough, even at some altitude in our Alps as shown below - dawn at 2,100 m (6,900 ft), North Rams Head, Kosciusko NP, Australia. Of course, if we have spare dry clothing available I often fold that up and put it under our feet as well.

Therm-a-Rest ProLite 3 Air Mat Product Review - 5
Dawn at North Rams Head, 2,100 m, Kosciusko NP, Australia.

Sliding Around

We met a significant problem in the field with the way the mats slide around on the silnylon floor of our blue tent. My impression is that the PU dots are really good at sliding on the silnylon, and discussion with my contact at Cascade Designs more or less confirmed this.

I spoke with Doug Jacot, our Therm-a-Rest director. He said that the problem is the Sil-nylon groundsheet. Even the NeoAir, which has one of the best non-slip treatments, can slip on a silicone-treated floor. As you mentioned, adding the silicone sealant stripes to the floor of the tent really is the best option, other than to use a tent without a silicone-treated groundsheet.

Well, as expected, but I have to say that suggesting I change my tent was hardly useful! And I had already added silicone stripes to the floor of my tent, but they seemed to have very little effect on the sliding. I do wonder whether the dots are there not to stop sliding but to prevent abrasion of the fabric surface. The dots are small, but they are packed really close together, and they do slide well.

Therm-a-Rest ProLite 3 Air Mat Product Review - 6
ProLite 3 mat with silicone stripes added.

What the company did not suggest was putting the silicone stripes on the underside of the mat. So I tried this with Permatex Flowable Windscreen Sealant 65AR. You can see the stripes in the photo here. I want to emphasise that these stripes of silicone are really thin: I ran a very thin bead along, then smeared it out with my finger carefully. There are no lumps, and the weight gain would be in the order of maybe 2 - 3 grams. Making the stripes any thicker would not improve their grip. After a rather serious trip in Wollemi NP (a long story...) I can confirm that these stripes made a huge difference: the mat did not slide around. It may be that the silicone stripes on the mat did grip against the silicone stripes on the groundsheet: you may need both. With all due respect to Cascade Designs, I have to ask why they can't do the same thing?

R-Value

We all know that some companies make exaggerated claims for the insulation value of their clothing, sleeping gear, and mats. We mentioned above that the claimed R-value for the ProLite is 2.2, but obviously this should be measured. Using our insulation test system we measured the ProLite mat with the bottom surface cold and the top surface hot - the way you would use the mat in the field.

Therm-a-Rest ProLite 3 Air Mat Product Review - 7
ProLite mat R-value.

Making the measurement takes time, as mats are good insulators and the heat flow is slow to stabilise. There is always a transient at the start which purely an artifact of how insulation testing works, so we have to ignore that. The plot here shows the R-value at several different thicknesses, from fully inflated (and lightly loaded) to under-inflated and heavily loaded.

You should note that this test started with the mat inflated with a few breaths on top of its normal self-inflation, and this does not completely reflect field use. In the field your hips and your shoulders will depress the mat locally, reducing the R-value right under them. Also, you may not blow the mat up fully as that tends to make it rather hard. When the mat is under-inflated just a little bit you get more of it supporting you, which is more comfortable, although this means some bits of you may be a bit cooler than other bits. That's normal.

My assessment is that the claimed R-value of 2.2 is fairly honest, although if you go for 'comfort,' bits of you will see a slightly lower R-value.

Summary

Do we like these mats? For non-snow use, we do. We haven't tried them in the snow, and probably won't. Even though they are thinner (at 25 mm or 1 in) they seem to be quite comfortable, and at 310 g (11 oz) they are much lighter. With a quoted R-value of 2.2 and a measured consistent with that, they have less insulation than our Deluxe LEs (about 6.7) which we use in the winter on snow, but they seem fine for three-season use.

Specifications

Manufacturer Cascade Designs
Web Site www.cascadedesigns.com
Model ProLite, Small (3/4 length)
Size (measured) Small: 505 x 1200 mm (20 x 47 in)
Thickness 25 mm (1 in) - approx, depending on inflation
R-value Claimed 2.2, measured 2.5
Weight (quoted) 310 g (11 oz) for Small
Weight (measured) 315 g (11.1 oz) for Small
MSRP US$80 for Small
Other sizes Extra Small: 510 x 910 mm (20 x 36 in), 230 g (8 oz), US$60
Regular: 510 x 1830 mm (20 x 72 in), 460 g (16 oz), US$100
Large: 630 x 1960 mm (25 x 77 in), 630 g (22 oz), US$120

What’s Good

  • Light weight
  • Self inflating
  • Comfortable
  • Seem tough enough

What’s Not So Good

  • They slide around on silnylon!

Disclosure: The manufacturer provided this product to the author and/or Backpacking Light at no charge, and it is owned by the author/BPL. The author/Backpacking Light has no obligation to review this product to the manufacturer under the terms of this agreement.


Citation

"Therm-a-Rest ProLite Air Mat Product Review," by Roger Caffin. BackpackingLight.com (ISSN 1537-0364).
http://backpackinglight.com/cgi-bin/backpackinglight/therm-a-rest_prolite_3_air_mat_product_review.html, 2011-02-01 00:00:00-07.

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Therm-a-Rest ProLite 3 Air Mat Product Review
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Addie Bedford
(addiebedford) - MLife

Locale: Montana
Therm-a-Rest ProLite 3 Air Mat Product Review on 02/01/2011 14:54:35 MST Print View

Companion forum thread to:

Therm-a-Rest ProLite 3 Air Mat Product Review

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
re on 02/01/2011 15:10:55 MST Print View

Good to see a review of this new model.

By the way, it's not called a Prolite 3, it's called a Prolite.

And the old Prolite 4 is now called a Prolite Plus.

You might want to change the article to have the correct name so as to not be confusing (as if that's possible with their screwy naming convention).

David Pex
(dpex) - MLife

Locale: Pacific NW
ProLite Air Mat Durability on 02/01/2011 15:40:49 MST Print View

I am not sold on the Prolite (by any name). It failed on me part way through my JMT hike last year (just after leaving VVR going south), and despite numerous attempts at field repair, it continued leaking. At first, I located two slits on the underside that I patched. But after patching these leaks, more slits became apparent that I either had not noticed the first time, or developed after the first patch. This happened three or four times until I finally resigned myself to a flat pad for the remainder of the trip. This was not so bad until the last three nights (starting at Tyndall Creek) when the temperature dropped into the 20s at night (late August). That's when I missed the lack of insulating capability of a flat airmat. Upon my return, I took the pad back to REI, and have gone old-school, with an old-fashioned blue foam closed-cell, cut to the shape of a Prolite. A bit bulkier to pack, but lighter, cheaper, and totally flat-resistant.

Addie Bedford
(addiebedford) - MLife

Locale: Montana
ProLite Naming on 02/01/2011 16:05:50 MST Print View

I verified that - thanks Jerry! The changes are made everywhere but the URL, where I can't change things without breaking other things.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
re on 02/01/2011 17:36:04 MST Print View

I've used my regular size Prolite for about 150 nights.

No problems with leaks.

Fairly comfortable to sleep on but I sleep better in a regular bed.

It doesn't slip on my silnylon, but that's because I coated the silnylon with silicone diluted with mineral spirits (1:4) so it's almost sticky.

There's all this buzz about the Neo-Air, but I think this Prolite is better - only slightly heavier, not as comfortable, self-inflating but I always add about two puffs, I think it's less likely to have an air-leak and if it did it would retain some warmth and comfort

Nate Powell
(powell1nj) - F

Locale: North Carolina
re: ProLite Review on 02/01/2011 18:20:19 MST Print View

+1 to the ProLite series. I've used one for years and it's served me well. The only time I've ever had a leak was definitely operator error. I was trying one of the thermarest chair converters and for some reason thought it was a good idea to have a seat next to the fire. Yeah...

If I were going to buy a new one I'd probably buy the women's version. It's only six inches shorter and has an R-Value of 2.8 instead of 2.2. A pack or extra clothes would easily make up the missing 6" as a pillow or footpad.

Very nice review as usual.

George Matthews
(gmatthews) - MLife
Re: Therm-a-Rest ProLite 3 Air Mat Product Review on 02/01/2011 19:30:07 MST Print View

Another excellent review. Thanks.

Really enjoy the pictures with your views looking out of you tent. Beautiful places!

James Klein
(jnklein21) - M

Locale: Southeast
note on testing on 02/02/2011 10:54:48 MST Print View

Roger,

As usual, great article.

Regarding ignoring the transient...it makes since that you would for R-value determining. But IMO that transient would definatly be a piece of info to consider. A long time to reach steady state means a long time of elevated heat loss.
Two pad w/ equal steady-state R-values but significantly different heat capacities will feel much different during that transient period. For pads of equal R-value I would want the one with the lower heat capacity (and thus the shorted trasient in your test).

James

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
How do you measure R value on 02/02/2011 11:02:59 MST Print View

Roger, how do you measure R value?

David Kelly
(dkelly) - F

Locale: Maryland
Therm- a- rest pad on 02/02/2011 14:00:17 MST Print View

I've used the 3/4 pad for the past several years, purchased one for my oldest son before we went to Philmont, since then purchased another one for my youngest son at an rei attic sale, said it leaks. I patched the leak & I use it now with no problems.I too add air since I like a firm surface. As far as something under my legs I put clothes under by sleeping bag. I have no complaints with all our backpacking trips over the past three years and will be taking it back to Philmont this year.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: note on testing on 02/03/2011 16:27:48 MST Print View

> Two pad w/ equal steady-state R-values but significantly different heat capacities will feel much different during that transient period.

True, but ...
I don't think the thermal mass of the airmat is more than 1% of a human body. (Actually, way less than that.) As such, I seriously doubt that the transient found during measurement will be significant in the field. Certainly, I have never noticed the effect myself, after sleeping on many of the mats.

Cheers

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: How do you measure R value on 02/03/2011 16:30:57 MST Print View

> how do you measure R value?

Ah yes. We have an article devoted entirely to the Thermal Insulation Measurement System I have built to specifically measure R-values. It will be published soon.

I will add that this is not the first one I have built: my team did build one when I was working for CSIRO Textile Physics many years ago. Anyhow, it's coming ... soon.

Cheers

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Re: How do you measure R value on 02/03/2011 17:13:09 MST Print View

"I will add that this is not the first one I have built: my team did build one when I was working for CSIRO Textile Physics many years ago."

You aren't trying to gather wool over our eyes, are you?

--B.G.--

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
re on 02/03/2011 17:34:35 MST Print View

That should be an interesting article, Roger

James Klein
(jnklein21) - M

Locale: Southeast
yeah on 02/03/2011 18:51:17 MST Print View

You're probably right about the relative importance but it would still be interesting to confirm.

Christine Thuermer
(chgeth1) - F
Delamination on 02/03/2011 21:19:02 MST Print View

I am very surprised that you do not mention one of the big problems of the Therma-Rest: Delamination!

I have been hiking and cycling for the last 3,5 years straight and I am always using a Thermarest Prolite (3) short. In these 3,5 years I have gone through 5 (five!!!) thermarests - all exchanged under warranty due to delamination.

I want to mention that in this whole period and 5 mats I never had a single leak. But after about 6 months of constant use the mat starts delaminating. That means that on chamber created by the punch out bursts, connects with the chamber next to it and creates one big chamber. If you continue using the mat more and more chambers will burst and create a bigger and bigger bubble - until you cannot sleep comfortably on it any more.

I am treating my gear very carefully (never had a leak), so this delamination does not stem from mistreatment of the mat - I think it is a quality problem. The only reason why I continue using Thermarest is their worldwide warranty policy. When the delamination starts, I just exchange it. The problem is so common that dealers in various countries (Germany, US, Australia and NZ where I had to exchange mats) knew about it at once and exchanged it immediately with no questions asked.

I would like to see a technical explanation for this problem on BPL. When I last exchanged a Thermerest in Australia I received a standard letter from the Australian Thermarest distributor claiming that this problem is caused by bacteria and funghus growth due to contamination through body oils - which did not make much sense in my eyes.

Could you give some explanation for that problem?
Christine

Edited by chgeth1 on 02/03/2011 21:27:18 MST.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
re on 02/03/2011 22:40:05 MST Print View

6 months of constant use - 180 days

Most people would take years to use it that much

Maybe it would be reasonable for something to wear out after years of use

Maybe that's just beyond what the Thermarest mattresses are capable of doing

Christine Thuermer
(chgeth1) - F
Delamination on 02/03/2011 23:29:22 MST Print View

I don't think that half a year of constant use is an unreasonable amount of time for a sleeping pad - especially for one that is not exactly cheap either...

To give you a comparison:
I am using a Tarptent Contrail and it has gotten more than 400 nights of use - and is still doing fine. I only had to replace the zippers.
My WM sleeping bag has seen more than 500 nights of use and still does fine.

In comparison to that 180 nights of use is not really much...
I think that Thermarest is aware of the delamination problem, but as not many people use their mats that long they just accept the return rate for delaminated mats. Still I think that Thermarest produces mediocre quality - they have not been able to resolve the delamination problem in 4 years. The delamination occured with the "old" Prolite 3 (orange) mat as well as it does with the new Prolite (red) one.

Christine

Franco Darioli
(Franco) - M

Locale: Melbourne
Therm-a-Rest ProLite 3 Air Mat Product Review on 02/04/2011 00:33:35 MST Print View

Hi GT
Franco

peter vacco
(fluff@inreach.com) - M

Locale: no. california
Re: Delamination on 02/04/2011 07:48:32 MST Print View

". Still I think that Thermarest produces mediocre quality"

now that there is a pretty hard slam at a company made up of some very skilled and polite people.
i suspect that what might be a better choice of slams is that they produce products of excellent quality, but that do not possess outstanding longevity. (i bet we might all agree on that feature.)

those of us who use their products at length know well of the delamination issue. i sleep on one at home, and recently, as expected, it inevitably delam'd, and now has a big bubble in it.

you can see a delam coming. and except on a very long trek, it's hardly an issue in that they'll front you another one.

for along trip .. buy a new one. you can always use another air mattress.
considering the landfills heaped with castoff computers gratis microsoft, and hp printers tossed by the millions, a mattress repair now and again is small pick'ns.

it has been my experience that delam occur directly under where is pivot on my right elbow when moving about. i suspect that the elbow imparts considerable shear into the fabric, and this is a contributing factor.

questionable as thermarest longevity may be, those chinese ones from pacific outdoor are worse.