For many years, I just used simple closed cell foam pads for everything; camping, climbing, whatever. I have a full length yellow Karrimat (closed cell evazote foam) that I bought in Hong Kong in the mid 1980’s that I used contentedly for decades. In really cold conditions, I just put a thinner evazote pad under my torso, and I was good.
However, as I’ve grown older, I have found that my old bones need a little more padding and insulation in order to get a decent night’s sleep and not wake up with aches in my shoulders, back, and hips. Because the ground has become harder and I’ve become softer, I’ve mostly migrated to inflatable sleeping pads. However, the exception to this is if I’m climbing and I’m going to be doing an open bivi without a tent. In this situation, I will still take a closed cell pad. Closed cell pads are pretty much indestructible, and can stand up to being scraped and poked on rough rocks. I use a length of shock cord to keep the pad rolled up, and when I lay the pad out to sleep on it, I thread the shock cord through a hole in one corner and use this to tie the pad down so it won’t blow away in the night.
The best closed cell foam pads are pressure blown evazote foam. The best place to buy them in North America is at Mountain Equipment Co-op in Canada. Cascade Designs makes a couple of closed cell foam pads, the RidgeRest and the Z-Rest. These pads are supposed to be more comfortable than traditional closed cell foam because of ridges or bubble shaped indentations built into the pads. I haven’t found much difference in actual use, however. The Z-Rest does have the advantage of folding easily and taking up marginally less space than a rolled pad. In use, however, I tend to prefer the smooth surface of the traditional evazote pads, as the smooth surface doesn’t collect snow or water like the surfaces of the RidgeRest or Z-Rest.
Self Inflating Open Cell Foam Core Pads
My first move away from closed cell foam was to a self inflating pad with an open cell foam core. These were first popularized by Cascade Designs as the Thermarest pad. I have used numerous variations of the Thermarest self-inflating pad open cell foam pads, typically favoring the lighter models in a half length size.
They’re a bit heavier than closed cell foam pads, but they are a lot more comfortable, and they fold up a lot more compactly than a closed cell pad.
Over the years, self inflating pads have become lighter and more compact.
The big concern with these pads is that they are susceptible to getting punctured. Mark Twight, in his book, Extreme Alpinism, discourages the use of inflatable pads for this reason. However, in all the years I’ve used them, I’ve only ever had one puncture of a Thermarest, and that was on a car camping trip. I repaired the hole with a repair kit.
Steve House used one on his ascent of Nanga Parbat. I guess if they’re good enough for House, they’re probably good enough for me.
Besides warmth and comfort, one of the the real benefits of an inflatable pad is that they are much less bulky when deflated and I can easily carry it inside of my pack rather than strapping it to the outside.
Here are my thoughts on some of the self inflating open cell foam core pads I’ve used.
Note that all of these pads are short length pads that go from shoulders to hips. I don’t use full length pads of this type as they are too heavy and bulky for my tastes.
Thermarest Prolite 3 small pad 14.2 ounces R 2.2 Comfort B- This is the current lightweight model of the classic thermarest. It packs small, and has enough insulation for 3 season use. It’s not particularly thick, and you need to blow it up a bit as it needs to be inflated firmly for comfort, particularly for side sleeping.
Thermarest Prolite Plus small pad 16.6 ounces R 3.8 Comfort B This is the winter version of the classic thermarest. It’s thicker, which provides more comfort and also more insulation in cold weather. It’s a bit heavier and bulkier than it’s three season sibling.
Ortik Backlite small pad 13.9 ounces R 4.5 Comfort B-This is a minimalistic sleeping pad that is targeted at alpine climbers. It is slightly thicker than the Thermarest Prolite 3, but it has a more tapered shape. It has the best non-slip surface of any of the pads, and when deflated, scrunches down to a very compact package. Ortik lists the R value as 4.5, but I don’t think I trust this R rating. Unless there’s some hidden magic going on with this pad, my guess is that the R value is likely closer to an R3, as this pad is part way between the Prolite and Prolite Plus in thickness. (I haven’t slept on it in cold enough weather to actually ascertain a lower limit for this pad.)
Inflatable Air Mattress Pads
Recently, a new type of inflatable sleeping pad has come onto the market. These are inflatable pads that don’t have an open cell foam core. Obviously, inflatable pads have been around a long time. Your standard Wal-Mart slumber party air mattress is an inflatable pad. However, these pads typically have been heavy and have had poor insulative value in cold weather.
These drawbacks of air mattresses have been addressed with the use of ultra-light materials and the clever addition of reflective and/or insulating materials inside of the air mattresses. Exped air mattresses use down or synthetic materials in their air mattresses to provide insulation, while Cascade Designs (the Thermarest company) uses reflective films and baffles to provide insulation in their NeoAir air mattresses. The result of eliminating the open cell foam core means that these air mattresses are lighter and less bulky than traditional Thermarest type mattresses.
The down side of these air mattresses is that if they are punctured, they provide almost no insulation at all, (while with a standard thermarest, you still have some insulative value from the open cell foam.)
Although there were initial reports of numerous defective Neoair mattresses when they were first released, Cascade Designs seems to have worked out these quality control issues, and the current crop of air mattresses seem to be less prone to popping and leaking. I’ve got about 40 nights on various models of these air mattresses, and have yet to have a problem with leaking, even though most of these nights I was sleeping with the mattress directly on the ground (no tent floor.)
These air mattresses have pretty much replaced the open cell foam core inflatable mattresses as my standard pad for just about any activity now.
One note on these mattresses. The tend to be significantly thicker than other types of sleeping pads. Because of this, I find that I am not comfortable sleeping on a half-length pad. My first Neoair pad was half length, and I found that my legs hung off the end in an uncomfortable manner. Because of this, all of my inflatable air mattress pads are now full length.
NeoAir full length pad 13.6 ounces R 2.5 Comfort A This was the original Cascade Designs air mattress. It relies on reflective insulation baffles to provide insulation. I really like this pad a lot. It’s more comfortable than a traditional open cell foam Thermarest, and is relatively light and compact. It’s a little bit crinkly and noisy, but that doesn’t bother me much. I’ve used this pad directly on the ground, and haven’t had any punctures, in spite of the occasional contact with rocks, sticks, and pine needles. Cascade Designs now has an even lighter model out, and they will no doubt continue to improve them as time goes on.
NeoAir All Season full length pad 17.9 ounces R 4.9 Comfort A This is the 4 season version of the Neoair. It’s a bit heavier, but it provides almost double the insulative value of the regular Neoair. I have used this pad in temperatures hovering around zero degrees Fahrenheit, and never felt any cold seeping in from below. It’s very comfortable, and the surface seems a bit softer and less slippery than the regular Neoair.
NeoAir XTherm full length pad 15.5 ounces R 5.7 Comfort A- This is a lighter weight version of the All Season. It has a tapered shape, which reduces weight, but also reduces the sleeping area, particularly at the foot section. This pad is reportedly even more insulative than the All Season, although I can’t confirm that with actual use, as I received mine in the month of April, after the cold winter months had passed. I have slept on it, however, and it is quite comfortable, comparable to the original Neoair. I gave it a slightly lower comfort rating than the two other NeoAir mattresses because of its tapered shape, which leaves less room for the feet. One nice feature on this pad compared with the other NeoAir pads is that the fill knob doesn’t face upwards, so it doesn’t poke you in the face if you lay your head on it.
Exped Synmat UL 7 full length pad 16.1 ounces R 3.1 Comfort A+ This is my most comfortable sleeping pad. There are a few things about this pad that lead me to give it the highest comfort rating of any sleeping pad I’ve used. First of all, the baffles on this pad are oriented length-wise, with the outside two baffles slightly taller than the others. This means that I am much less prone to sliding off of this pad than any other I’ve used. The material the pad is made from is soft and comfortable and quiet, particularly when compared with the Neoair material. I also like the dual valve feature on this pad. There are two separate one way valves on this pad; one for inflation, and one for deflation. This makes blowing the pad up easier, as air doesn’t escape from the one way valve as you are blowing the pad up. The Exped also rolls down into a very compact package, which is great for long trips, where space is at a premium. Although it is not the lightest of the pads, the Exped is perhaps my favorite of the 3 season pads due to its outstanding comfort and ease of use. It’s a good combination of small packed size, reasonable weight, good insulation, and top of the line comfort.
Klymit Inertia X-Series Pads
There is another, very different type of inflatable on the market as well. These are the strange looking Klymit pads; the full length X-Frame and the short length X-Lite. These inflatable pads have removed the sections where less padding is needed, and kept the padding at the head, shoulders, and hips. They come with a small bulb shaped hand pump to help inflate the pads to a very firm state. This pump only weighs 1.4 ounces and is pretty much essential in order to get the most out of the performance of these pads. These are far and away the smallest and lightest pads available. However, these pads have a few drawbacks First of all, they are not as comfortable as other inflatable pads. They are a step above closed cell foam, but lag behind the other inflatable pads in comfort. The other shortcoming is their cold weather performance. The pads don’t have any significant insulative value. In frigid conditions, cold seeps up from below. Some folks use these pads in cold weather in conjunction with a closed cell foam pad, but that kind of defeats the compact and lightweight benefits of this design. For warm weather, these pads are adequate, and are certainly a step up in comfort if you’re used to sleeping on a closed cell foam pad. They are a bit Spartan for my needs, but for someone who currently uses a lightweight closed cell foam pad, these Klymit pads are a very attractive ultralight alternative, particularly the tiny X-Lite.
So, which pad is best? That really depends on use.
For climbing bivis without a tent, I choose the traditional closed cell foam pad. When you’re planning on sleeping on sharp pointy rocks etc., the durability and fool-proof nature of closed cell foam offsets it’s relative bulk.
For three season use, my pick is the Exped Synmat UL 7. It’s a little heavier than the NeoAir competitor, but I love the comfort enough to carry the few extra ounces.
For winter use, the Xtherm seems to be the winner. It has higher R values and lighter weight than the other cold weather competitors, and has reasonably small bulk when packed as well. Unfortunately, I have not had the chance to use this pad in really cold weather, so my conclusions regarding cold weather performance with regards to the XTherm are based solely on my experience with the NeoAir AllSeason and the manufacturer’s specs for this pad.
Below is a chart that compares the various pads. Weights are as weighed by me. R-Values are as provided by the manufacturers. These R Values are not necessarily consistent between different manufacturers, however. My personal experience indicates a higher actual R-value than that listed for closed cell foam evazote pads. My comfort grade is simply my personal opinion of the relative comfort of the pads. The grades shouldn’t be looked at as a statement on absolute comfort, but rather a comparison among the various pads. I’m a side sleeper with achy joints and a history of joint and back injuries, so I tend to grade rather hard on comfort. Someone with less aches and pains or someone who sleeps on their back may have graded many of the pads a bit higher on comfort than I did.