CLOSED CELL FOAM PADS – PART 2

CCF pads available in the US

The most popular ccf pads in the US seem to be Therm-a-Rest’s pads, which include their classic RidgeRest with the ribbed imprints, their foldable Z-Lite with egg-crate countering, and their newer aluminized “SOL” versions of both.  It is very common to see someone on the trail with the rectangular folded Z-Lite pad (or one of its cheaper knock-offs) strapped to the outside of their pack.

Many ultralight backpackers are fans of Gossamer Gear’s NightLight pad, which serves double-duty as a back pad to give structure to their very popular frameless packs.  It is also egg-crate shaped, but it is smooth and flat on the other side; the bumps are not hollow underneath like in the Z-Lite. They also sell a 1/8” ThinLight pad, that is commonly used paired with an inflatable pad or by itself by the most extreme super-ultralight hikers, and a 1/4” ThinLight pad marketed to hammock-users but perfectly fine for ground-sleeping as well.

Nunatak, a leader in high-end sleeping bags, once made an egg-crate Lunapad, similar to the NightLight, but they have since discontinued its production.  These pads are both descendants of the popular but long-gone Mt. Washington ccf pad.

Oware is another cottage company that, while less well known than Gossamer Gear, offers a 3/8” pad and a 1/2″ pad in several sizes that are often recommended on ultralight forums.

Exped, Therm-a-Rest’s main competitor in the mainstream US sleeping pad market (although Big Agnes, NEMO, and Sea-to-Summit have big presences as well), makes a few ccf pads that I rarely hear any talk about.  You can also get some generic foam pads and Z-lite knock-offs from REI, ALPS Mountaineering, Coleman, and various other random companies – I included any I found that had sufficient data for comparison.

The UK-based company Multimat is another company that not many people talk about or use their pads, partly because few of their pads are even available in the US.  However, they have a wider range of ccf pads than any other company and are using many different type of foam and foam technologies in their pads. In researching foams for this article, their staff were very helpful in educating me about the different types of foam they use in their low-end, medium-end, and high-end pads, and how those differences relate to warmth and durability. Unfortunately, I could only find 5 out of their 14 pad options available for sale in the US, through Emergency Outdoors, Mad City Outdoor, and a few Ebay and Amazon sellers.

 

Comparing CCF pads

I attempted to compile data on all the ccf pads available in the US market, and include inflatable and self-inflating pads for comparison.  For some pads, primarily the low-end generic ones I found on Amazon, I was not able to find sufficient data on weights and R value/temperature rating to include them in the data table.  Also, rather than include every inflatable and self-inflating pad available, which is not the focus of this article (see Section Hiker’s sleeping pad article for a more comprehensive list), I chose to exclude any pad with a total weight greater than 20 ounces (1.25 lbs). This threshold was chosen to still include the most popular inflatable pads used by ultralight backpackers, and honestly if you’re willing to carry a pad weighing more than 20 ounces, ccf pads are probably not the ideal choice for you and you should stop reading now.  My survey resulted in a total of 133 pads: 51 ccf pads, 67 inflatable air mattresses (insulated and uninsulated), and 15 self-inflating pads.

As pads vary in material, thickness, width, length, and shape, it is difficult to simply compare pads based on their reported R values, total weight, or price, to determine which ones are the best value.  In compiling the data on these pads, I chose several different composite measures to better compare pads on equal terms.

The first composite measure is the Fabric Weight – this is the pad’s total reported weight divided by its area (length x width), with the units in ounces per square yard.  While pads, particularly inflatable/self-inflation, can include other components such as valves and grommets that add to the weight but are not dependent on the pad’s size, this composite measure is a good way of comparing the weight of pads while keeping area constant, independent of whether they are regular length, torso length, extra wide, etc.  For pads that are not rectangular, length x width overestimates the area and thus underestimates the fabric weight.  For some of these pads, both shoulder width and foot width were provided, and I used as width the average of these two widths to calculate area.  For others, I used the fabric weight of the rectangular version of the same exact pad.  Notable exceptions were the popular Therm-a-Rest NeoAir XLite pads, which don’t have rectangular versions and I could not calculate a more accurate estimate of area.  For these, I have left the fabric weight and subsequent composite measures as is, but I have noted in the comments that the area is overestimated, and thus fabric weight and other composite measures will seem better than they really are.

The second composite measure I used is the R value divided by the fabric weight (multiplied by 10 to make the numbers easier to discuss).  This provides a composite of the two factors backpackers care most about: minimizing fabric weight and maximizing insulation.  I will refer to this measure as Weighted R, and I feel this is the best single measure by which to rank pads – the higher the weighted R, the better the warmth to weigh ratio.  If we do some unit conversion, we discover that weighted R is simply the reciprocal of the product of a foam’s density and its thermal conductivity; a combination of low density and low thermal conductivity (which often go hand in hand) will produce the highest weighted R. When possible, I used the R value provided by the company (or converted tog values for the UK-based Multimat pads). For some pads, I estimated the R value based on the provided temperature rating, and in a few cases I estimated the R value based on the expected thermal conductivity for the type of foam used.

If you’re like me, you’re also concerned about cost.  It doesn’t matter so much once you have a pad, but it matters a lot before you have one.  The third composite measure I used is price per square yard divided by R value, what I will call Cost Effectiveness. While you would expect pads with more insulation to be more expensive, some pads are a better deal in terms of the raw warmth you get per dollar spent. This measure is especially helpful if you are considering layering two pads on top of each other to increase the total insulation, are buying a pad to cut down to the size you want, or want to compare the cost of a pad to the cost of different types of ccf that you can buy directly from foam suppliers (more on that in Part 3). For price, I used discounted prices from assorted online vendors when available; if not, I used the price on the company’s website.  While MSRP prices are less volatile and not dependent on the timing of discounts, I felt only using MSRP would unduly penalize the more expensive mainstream pads that are regularly available with deep discounts.

 

Top Ranked Pads

The google spreadsheet with the data on 51 ccf pads and an additional 82 inflatable pads for comparison can be found here .  You can sort it by any of the data columns that you wish to rank the pads.  I will discuss how the pads compare for my 3 composite measures.

Fabric Weight

When we consider fabric weight (the weight of the pad when area is kept constant), ccf pads easily outcompete inflatable pads.  Of the 133 pads, the top 27 pads with the lowest fabric weight were all ccf pads. While an inflatable pad may seem light when deflated and rolled up, for the area covered the fabric used in inflatable pads is simply much heavier than closed cell foam, in addition to the weight of air valves and any insulation.  Within ccf pads, thickness is the main factor determining which pad has the lowest fabric weight, with Gossamer Gear’s super-thin 1/8” Thinlight pad taking the #1 slot.  If all you care about is covering the area below you with a minimal amount of insulation and protection from water and dirt, then these are good options. Thin ccf pads are especially popular among hammock users where comfort is less an issue and where the thinner material molds better to the curvature of the hammock.  However, with proper site selection, some ground sleepers are still able to sleep comfortably on these super-thin pads.  They are also a great choice if you are looking for a ccf pad to supplement your comfortable inflatable pad.

Rank	Company	Name	Thickness (in)	Fabric Weight (oz/yd2)
1	Gossamer Gear	Thinlight Foam Pad – 1/8″	0.125	2.94
2	Exped	Doublemat Evazote	0.2	3.85
3	Oware	Foam 3/16″	0.1875	4.48
4	Jacks R Better	EVA Closed Cell Foam Pad	0.25	5.15
5	Exped	Multimat	0.1	5.39
6	Multimat	Camper 8	0.315	5.84
7	Multimat	Superlite 9.5 XL	0.374	6.10
8	Multimat	Superlite 8	0.315	6.11
9	Gossamer Gear	Thinlight Hammock Pad – 1/4″	0.25	6.25
10	Multimat	Trekker Voyager 8	0.315	6.75

Warmth to Weight Ratio

When we look at weighted R value (R value x 10 divided by Fabric Weight), all the top ranked pads are the insulated inflatable pads.  The top 10 include the Exped Downmat HL, Therm-a-Rest NeoAir Xtherm pads, Big Agnes Q-Core SL, Therm-a-Rest NeoAir Xlite pads, and Exped Synmat HL Winter pads.  These pads are all able to provide high R values with only a small increase in weight, achieving very high warmth to weight ratios.  Ccf pads by an large don’t provide high R values, with only 1 ccf pad even having an R value above 3 (the RidgeRest Solar) and its weighted R is below that of many other ccf pads.  To get a higher R value with ccf, either you need a thicker pad than what is available (and it would be quite difficult to roll) or you have to layer several pads. Many backpackers do layer a torso ccf pad over a thinner full-length ccf pad (like pairing the GG NightLight with the 1/8” Thinlight).  However, a thicker ccf pad or layering several ccf pads (which will obviously be heavier) are not going to improve the warmth to weight ratio.  Thus, when you need significant insulation for winter and cold shoulder-season trip, it appears that a quality insulated inflatable pad like those listed above is your best choice.

R values may not be the whole story, though.  Multimat uses a 3-level rating system for indicating which pads are summer, 3-season, or true winter pads.  It produces 8 level-4 pads rated for 3-season, with R values ranging from 1.11 to 1.77, while it produces 6 level-5 pads rated for winter, with R values ranging from 1.44-2.07.  Only 2 of the winter pads have R values exceed the R value of the highest rated 3-season pad.  Based on my discussion with Multimat, they take into consideration the quality of the foam in their rating, with a denser, less compressible foam with more consistent manufacturing considered more winter-worthy than a less dense, more easily compressed, and lower quality foam considered less winter-worthy even if both have similar measured R values in the lab. It appears that Multimat does a lot of field testing as well to back-up R values from the lab and they know which pads can hold up in winter.

Many recommend that winter backpackers take a sleeping pad with an R value of at least 4, ideally 5 or higher.  But the Multimat winter-rated pads have R values from 1.44 to 2.07.  I’ve read reports from some ultralight backpackers that they sleep warm in winter conditions with the egg-crate Gossamer Gear Nightlight/Nunatak Lunapad/Mt. Washington pads (all rated at an estimated R 2.27). Oware considers its 1/2” Plastazote pad with R 2.0 to be winter-suitable.  It may be that for R values significantly higher than 2, it is not suitable to make a direct comparison based on R values between ccf pads and insulated inflatable pads; or in other words, can an R 2.0 ccf pad be as warm as an R 4.0 inflatable pad? The answer likely ultimately lies in the fact that R values are based on measures of thermal resistance in the lab, for example detecting how long it takes a 1 degree difference in air temperature between the 2 sides of the insulation to reach equilibrium.  In the field, your body is compressing the pad, which changes the conditions, and your body and the pad are losing heat in other ways not directly measured by thermal resistance such as radiative heat loss and convective heat loss from wind. It may be that under these complex conditions, a ccf pad with a lower R value can feel just as warm as a higher rated inflatable pad.  I do not have any direct experience sleeping on snow with an R 2.0 ccf pad vs an R 4.0 inflatable pad to know if there is a significant difference, but I would be very interested to hear of others’ experiences.

Since this article is about ccf pads, let’s focus on the range of R values of the great majority of ccf pads. When we look only at the ccf and inflatable pads with R values of 3 or below, then we do see ccf pads topping the list for warmth to weight ratio, with the top 27 out of 88 pads being ccf.  The Exped Multimat is the highest ranked ccf pad, but Exped’s reported R value of 1.4 is just way too high for a 0.1” thick pad.  The Therm-a-Rest SOLite – Small version also has a reported weight that appears a little low, when compared to the Regular and Large versions.  Omitting these 2 pads, I have listed below the top 10 ccf pads for weighted R, combining pads that were the same except for size. We find that the top 2 ccf pads for warmth to weight ratio are Multimat’s Superlite 9.5 XL and Oware’s 1/2″ pads, both made out of Plastazote 1.4 pcf.  By having the lowest density of any of the available ccf pads as well as thermal conductivity values competitive with other high quality foams, these combine to produce high weighted R values.  The next 2 pads by Multimat use premium quality foam and lamination to increase insulation.  Unfortunately, none of Multimat pads making the top 10 list are currently available in the US.  Therm-a-Rest’s aluminizing on their SOLite pads apparently helps to reduce radiative body heat loss and increase their insulation.  However, even thick foam pads from ALPS make the top 10.

Rank	Company	Name	Material	Density (lb/ft3)	Thickness (in)	R value	Weighted R value
1	Multimat	Superlite 9.5 XL	Plastazote	1.4	0.374	1.53	2.51
2	Oware	Foam 1/2″ Thick	Plastazote	1.4	0.5	2.00	2.47
3	Multimat	Backpacker 9	IXPE-vertical/2-color laminate	1.8	0.3543	1.77	2.35
4	Multimat	Trekker Voyager 8	IXPE-vertical/2-color laminate	1.8	0.315	1.56	2.31
5	Multimat	Camper 8	XPE	1.5	0.315	1.34	2.29
6	ALPS	Foam Mat 625	Polyethylene	1.5	0.625	2.50	2.23
7	Therm-a-Rest	Ridgerest SOLite	Polyethylene-Aluminized	1.7	0.625	2.80	2.22
8	Multimat	Superlite 8	Plastazote	1.6	0.315	1.31	2.14
9	Multimat	Trekker Thermal 10 XL	XPE-Aluminized	1.6	0.3937	1.59	2.12
10	ALPS	Foam Mat 750	Polyethylene	1.6	0.75	3.00	2.08

Cost Effectiveness

To compare cost effectiveness, I took the best online price I could find for each pad, converted the price per square yard to calibrate for differences in size, and divided the price by the R value (not weighted R).  We again see that ccf pads top the list for most cost effective. The most affordable inflatable pad (Therma-a-Rest Trail Scout – Medium) comes in at #22, with the Klymit Insulated Static V Lite (#32) and Big Agnes Air Core (#35) following farther down the list.  The Therm-a-Rest NeoAir X-Lite Small, very popular among ultralighters, comes in at a whopping #121; even at the discount price of $100, its small coverage and moderate R value don’t provide good value for money (although comfort is another important factor).  In comparison, the Therm-a-Rest Ridgerest SOLite – Small is a similar size and weight with a slightly lower R value, but it is over 5x more cost effective than the NeoAir X-Lite.  For full-on winter pads with R value of 5 or higher, the most cost effective pad is the Therm-a-Rest NeoAir XTherm – Large (#46), although the Klymit Insulated Static V Lite provides an R of 4.4, is 50% more cost effective, and less than half the price of the XTherm.

Below is the list of the top 15 pads.  For pads with multiple versions in different sizes, I left only the most cost effective size in the top 15 list below.  I also omitted the Multimat pads that are not available for sale in the US (Trekker Voyager 8, Backpacker 9, and Comfort 12 XXL – their prices are from Multimat’s site converted from GBP to USD). With this list of 15, the top 10 are all ccf pads, but the inflatable Trail Scout – Medium comes in at #11.  The top 14 are all from mainstream companies, with the last #15 from Oware (and it is the most expensive pad overall of the 15 at $50 for the 2-person pad). This is likely because the mainstream company pads were almost all found with at least 25% discounts from MSRP, while the cottage company pads are listed at their regular price.  Therm-a-Rest’s RidgeRest Classic, aluminized Solar, or aluminized SOLite are all great deals for pads (although it seems the extra 0.9 in R value from the Classic to Solar seems elevated to justify the increased price).  Even though Multimat’s Trekker 10 XL has a reported R of 1.49, Multimat considers it a level-4 3-season pad. At only $12 for a full length 22”x73” pad weighing 9 ounces, the Trekker 10 XL is definitely the lightest, most cost effective 3-season option, with the big caveat being only if you are able to sleep comfortably on little over 3/8” of foam.

Rank	Company	Name	Price Source	R value	Price ($)	Cost Effectiveness (price per area/R)
1	Therm-a-Rest	RidgeRest Classic – Regular	Moosejaw	2.60	$15.00	$5.19
2	Multimat	Trekker 10 XL	Emergency Outdoors	1.49	$12.00	$6.48
3	Therm-a-Rest	Ridgerest Solar – Large	Moosejaw	3.50	$40.00	$7.69
4	Therm-a-Rest	Ridgerest SOLite – Small	Amazon	2.80	$16.00	$7.71
5	ALPS	Foam Mat Large 625	Amazon	2.50	$29.00	$7.81
6	Multimat	Trekker Thermal 10 XL	Emergency Outdoors	1.59	$16.00	$8.12
7	Therm-a-Rest	Z Shield	Moosejaw	1.50	$19.00	$9.50
8	Multimat	Discovery 10 XL	Mad City Outdoor	1.44	$17.50	$9.83
9	Therm-a-Rest	Blue Foam Pad	Therm-a-Rest	1.40	$20.00	$10.29
10	Therm-a-Rest	Z-lite SOL – Regular Limon/Silver	Moosejaw	2.60	$30.00	$10.38
11	Therm-a-Rest	Trail Scout-Medium	Moosejaw	3.40	$37.00	$10.68
12	Therm-a-Rest	Z-lite – Regular Coyote	Amazon	2.20	$28.00	$11.45
13	MEC	ZoteFoams Blue Foam-Regular	MEC (Canada)	1.40	$14.33	$12.06
14	Exped	Multimat	Moosejaw	1.40	$44.00	$13.14
15	Oware	Foam 1/2″ Thick – Two Person	Oware	2.00	$50.00	$13.50

Overall Best Pads

I have attempted to compare the pads in several different ways, so that you can evaluate them based on which composite measure is most important to you.  There are many other ways in which the pads could be ranked and I invite you to play around with the spreadsheet, re-sorting by different columns of your choice.  Lastly, I’ve combine each pad’s rank across the 3 composite measures, giving each measure equal rank, to crease the following list of the top 18 pads (excluding the Exped Multimat with its over-rated R value and the Multimat pads not available in the US).  I’m listing 18 because that’s how many I needed to include the top rated inflatable pad, the Therm-a-Rest NeoAir XLite Women’s pad.  There are 17 closed cell foam pads that have an overall combined rating better than the best inflatable, and the NeoAir XLite Women’s is also more than double the price of any of the better ranked ccf pads.  The Oware 1/2” pads, Multimat’s Trekker 10 XL and Thermal 10 XL, Therm-a-Rest’s RidgeRest Classic and SOLite, and ALPS generic foam mats all top the list for combined fabric weight, warmth to weight ratio, and price for warmth. And apart from the extra wide 2-person Oware pad which is a great deal if you need 2 pads or want to double it up for a full 1” torso pad, the rest can be had for under $40.

Rank	Company	Name	Thickness	Width	Length	Weight	R	Price
1	Oware	Foam 1/2″ Thick – Two Person	0.5	40	60	15	2	$50
2	Multimat	Trekker 10 XL	0.39	22	73	9	1.5	$12
3	Oware	Foam 1/2″ Thick – Torso	0.5	20	40	5	2	$20
3	Oware	Foam 1/2″ Thick – One person	0.5	20	60	7.5	2	$30
5	Multimat	Trekker Thermal 10 XL	0.39	22	73	9.3	1.6	$16
6	Therm-a-Rest	RidgeRest SOLite – Small	0.625	20	48	9	2.8	$16
7	ALPS	Foam Mat XL 625	0.625	30	77	20	2.5	$35
8	ALPS	Foam Mat Large 625	0.625	25	77	17	2.5	$29
9	Therm-a-Rest	RidgeRest Classic – Small	0.625	20	48	9	2.6	$15
10	Therm-a-Rest	RidgeRest SOLite – Regular	0.625	20	72	14	2.8	$25
11	Therm-a-Rest	RidgeRest Classic – Regular	0.625	20	72	14	2.6	$15
12	ALPS	Foam Mat Regular 375	0.375	20	72	9	1.5	$20
13	Jacks R Better	EVA Closed Cell Foam Pad	0.25	16	22	1.4	1	$5
14	ALPS	Foam Mat Large 750	0.75	25	77	20	3	$36
15	Therm-a-Rest	RidgeRest SOLite – Large	0.625	25	77	19	2.8	$35
16	Therm-a-Rest	RidgeRest Classic – Large	0.625	25	77	19	2.6	$22
17	Exped	Doublemat Evazote	0.2	39	79	9.2	0.8	$52
17	Therm-a-Rest	Z Shield	0.38	24	72	12	1.5	$19
18	Therm-a-Rest	NeoAir Xlite Womens	2.5	20	66	12	3.9	$120

You can access the full spreadsheet at any time here:

https://docs.google.com/spreadsheets/d/16IRegq78tFZOVVGvgyzRyPbIoGeDQfpUWIfs9m2xQ_o

In Part 3, I will discuss different types of foam you can purchase from foam suppliers if you want to make your own pad with a custom size or thickness.

CLOSED CELL FOAM SLEEPING PADS

Insulating yourself from the heat-sucking ground and providing comfort from your bones grinding into the hard ground or tent platform are critical to have a good night’s sleep when backpacking.  Sleeping pads come in 3 main types: closed cell foam (CCF) pads, inflatable pads (air mattresses), and self-inflating pads.

Many backpackers choose to sleep on a CCF pad because they have had bad experiences with punctures in the past using inflatable pads, while some simply are able to sleep comfortably enough on a CCF pad and choose it for its low weight and cost. And many backpackers use a combination of both: some put the CCF pad below their inflatable to provide protection from punctures, while others put the CCF on top to get the most insulative benefit (discussion of that is beyond the scope of this article, but trust me that all things being equal you will sleep warmer with the CCF pad placed between you and the inflatable than between the inflatable and the ground).

Comparison of the pros and cons of using CCF vs inflatable pads

Closed Cell Foam Pads	Inflatable Pads
Resistant to puncture Lightweight (in general) Warmer than an uninsulated air pad Low cost	More comfortable Take up little volume when deflated and folded Many types of insulation technologies
Bulky Less comfortable Need straps to secure rolled up (unless foldable-style) Confusing variety of different foam types used	Can be punctured Hard to find and repair punctures in the field Higher cost (especially for insulated) Need to be inflated (adds up after many nights) Need to be deflated (pushing all the air out every night adds up even more)

What is closed cell foam?

Closed cell foam refers to how the air pockets in the foam are not interconnected, resulting in a foam that is generally denser, waterproof, more insulative, more resistant to damage, and fairly stiff and uncompressible. Open cell foam has air pockets that are interconnected, resulting in a spongier foam that is generally less dense, less insulative, will absorb water or allow it to pass right through, and is usually relatively easy to damage.  Open cell foam usually compresses more and is more comfortable to sit on; it is used in mattress and seat padding and inside some inflatable and self-inflating pads.  In the past, some “foam” sleeping pads used open cell foam encased in waterproof fabric, but as closed cell foam technology has improved and diversified, different types of CCF have become the clear choice for foam sleeping pads.

Almost all CCF sleeping pads sold today use low density polyethylene (LDPE) because of its flexibility, low weight, durability, and moderate softness.  Polyurethane foam (PU) is still very occasionally used; it is heavier (more dense) but does usually provide more insulation per inch of thickness.  Many sleeping pads in the past (as well as exercise and yoga mats still today) were made of polyvinyl chloride/nitrile rubber (PVC/NBR or Ensolite); these pads deteriorated under extended UV exposure and are no longer used.  Note you will sometimes see a CCF sleeping pad’s material listed as polyolefin foam – this is not very descriptive as polyolefin can refer to polyethylene or any of a wide range of other plastics; in these cases, I would assume the pad is made of LDPE.

Polystyrene (Styrofoam) is another type of closed cell foam we are all familiar with.  Commonly used in packaging as well as house insulation, it provides more insulation per weight than polyethylene, but because it is rigid and breaks easily, it is not suitable for backpacking except perhaps as a small sit pad.

Types of Polyethylene Foam

There are two main types of LDPE foam used in pads: extruded and cross-linked, with cross-linked being further subdivided whether it is chemically cross-linked or physically cross-linked. Extruded polyethylene (abbreviated as PE, PEF, or LDPE) is produced by blending molten polyethylene polymer with a gas under high pressure.  The hot liquid-gas mixture is then extruded onto a conveyer at atmospheric pressure where the gas quickly expands to form bubbles and the polymer cools into a solid, trapping the gas in interstitial cells. A common additive to LDPE is vinyl-acetate, referred to as EVA foam (ethylene-vinyl-acetate), which makes the foam softer, more rubbery feeling, and more UV resistant.

Chemically cross-linked polyethylene (abbreviated as PEX, XPE, or XLPE) involves adding chemicals that create bonding in the liquid polymer before initiation of the foaming process, resulting is smaller cell size and a smoother surface to the foam. Physically cross-linked polyethylene (IXPE) usually uses some type of irradiation to produce even smaller and more consistent cell sizes, resulting in a very fine-textured foam.  The direction of the conveyer where the foam expands can also be orientated vertically instead of the traditional horizontal orientation, which affects how the cells form in the foam.  There are endless varieties of proprietary blends and processes for making different types of cross-linked polyethylene.  Two of the most popular proprietary foams used in pads are Evazote and Plastazote produced by ZoteFoams. Additionally, some foams are produced by laminating the same or different types of foam together; these will appear as having layers of the same or different colors when viewed in cross-section.  Some pads are also laminated with a thin layer of aluminum to reflect body height.

The main types of CCF used for pads:

Foam Type	Abbr.	Characteristics
Low-density polyethylene foam	PE, PEF, LDPE	Low-moderate durability, large cell size and difficult to roll, standard material used in foam swim tubes
Chemically cross-linked polyethylene	XPE, XLPE, PEX	Smaller cell size, higher durability
Physically cross-linked polyethylene (horizontal foaming)	IXPE	Small uniform cell size, high durability
Physically cross-linked polyethylene (vertical foaming)	IXPE	Similar to horizontal foaming, possibly lower thermal conductivity
Laminated cross-linked foam		Layers, improved durability, often more difficult to roll
Ethylene-vinyl acetate (PEF)	EVA	Softer rubbery feel, standard material used in floor mats
Evazote		Type of IXPE with EVA
Plastazote		Type of IXPE, less durable, available in low densities
Volara		Type of XPE with small uniform cell size
Minicel		Type of XPE with very small uniform cell size, soft smooth surface

 

Examples of different types of polyethylene foam, with the density indicated in pounds per cubic foot (pcf):

PE 1.2 pcf

PE 1.7 pcf

PE 2.2 pcf

XPE 1.5 pcf

XPE 1.5 pcf

XPE 1.5 pcf Aluminized

IXPE 1.8 pcf

IXPE 1.8 pcf

IXPE 1.8 pcf vertical-formed, 2-laminate

IXPE 1.8 pcf vertical-formed, 2-laminate

Plastazote 1.5 pcf

Evazote 2.1 pcf

Evazote 2.1 pcf

Evazote 2.1 pf

Evazote 2.2 pcf

Evazote 3.0 pcf

Evazote 1.7 pcf, 2-laminate

 

Comparing types of closed cell foam

As each type of foam can be produced across a variety of densities, it is very difficult to make generalized comparisons between the different foam types.  Most foams used for CCF pads have a density of 1.5-2.5 lbs/ft³.  As density increases, tear resistance increases but the force needed to compress the foam 25% or 50% increases, so there is a trade-off between durability and comfort. Denser CCF is too hard to sleep on and difficult to roll, while less dense foam is softer but less tear resistant.  Very low density CCF (<1.5 lbs/ft³) is sometimes used as sheets in packaging.  While these very low density foams could still be used for sleeping pads, this requires using a thicker, bulkier pad to avoid bottoming out or shredding your pad to pieces.  However, as we will see later, the lower density foams have the highest warmth to weight ratio.

In addition to weight, the other primary characteristic backpackers care about is insulation.  In the US, pads are normally rated by R value, a measure of thermal resistance.  R value is related to a material’s thermal conductivity – this is a measure of how fast heat passes through the material and has the units Btu*in/ft²*h*F.  R value is calculated by taking the material’s thickness in inches and dividing its thermal conductivity, with the units ft²*h*F/Btu. While R value will increase with thickness, thermal conductivity should be constant for a given material.  Materials with low thermal conductivity are good insulators, with things like argon gas or perlite under vacuum having extremely low conductivity (thermal energy passes very slowly through space with few atoms).   Sometimes the R value for 1 inch of material is given, which will remain constant for a given material, being simply the inverse of its thermal conductivity.  Outside the US, R values may be given in metric units (k/W).  In the UK, pads are often rated by tog value: 1 tog is equal to 0.57 R value (US).

For a given type of foam, thermal conductivity generally increases with greater foam density. However, as each type of foam can be produced across a range of densities and ccf pads rarely indicate what density of foam was used, it is very difficult to compare the thermal conductivity of different pads.  Density can be estimated based on the pad’s size and weight, but as pad manufacturing can add weight, this is only an approximation. Different technologies can further reduce thermal conductivity for a given density.  Here is my best attempt at ranking the types of foam from highest conductivity to lowest conductivity as:

non-cross-linked > chemically cross-linked > physically cross-linked (horizontal) > physically cross-linked (vertical)

Laminating foams together and aluminizing the foam can further reduce conductivity.  Some pads are formed in an egg crate shape; this should not affect the conductivity of the foam, but may allow insulation in your sleeping bag, quilt, or jacket to loft underneath you and further reduce conductivity.

Next in Part 2, I will survey the many ccf sleeping pads available in the US market and present compiled data comparing them.

Klymit Sleeping Pad Review

As an owner of 3 different Klymit pads, I thought it would be useful to do a comparison video.  I see a lot of recommendations for the Klymit Static V in my Facebook backpacking groups.  While it has nowhere near the insulation of the very popular NeoAir XLite pads which seem to be easily the #1 choice for ultralighters, for around half the price you can get a Klymit pad that weighs about the same (or even less with the Inertia X Lite) and will be sufficient for summer trips.

To give some background on my purchasing experience, I first bought 1 and then quickly 2 more of the original Static V, which my family and I have used on many trips and just sleeping at home on the floor for sleep-overs and such.  In my pursuit to go lighter, I bought the Inertia X Lite on sale last year to try it out.  On my first real trip, I actually pulled the bulb valve apart (you can see me inadvertently do this on the Inertia X Wave in the video).  I was able to superglue it back together in the field at night, without gluing my fingers together too badly, and slept on it for 2 more nights with only minimal leakage over the course of each night.  When I got home and reported the issue to Klymit and offer to return the damaged pad for a replacement, Klymit responded right away that they’d send me a replacement with no charge and that they didn’t need the original one back.  Thanking them for the great customer support, I asked if I could instead get a new larger Inertia X Wave and just pay the $5 difference in price at the time, which Klymit responded saying they’d be happy to send the Inertia X Wave instead at no additional charge.  I was able to better repair my old X Lite, so now I actually have 2 pads for the price of 1.  Great customer service from Klymit!

About the valve issue, this appears to be an inherent problem with the bulb valves on their pads that use it.  The valve is made of 2 pieces. The first piece is glued to the pad fabric and has a C-shaped casing with a hole in it.  The second piece is a cylinder with a release button, which has a small nozzle that inserts into the hole in the first piece’s casing, and then another nozzle on the other end that you insert into a bulb to finish pumping up the pad.  The factory gluing of these 2 pieces together does not appear to be sufficient, as my pulling the bulb off the valve has easily separated the 2 pieces in both pads.  Using super glue, I have been able to reglue the valves together in both pads such that they do not leak, at least at the valves.

Which brings me to the other issue, that of durability of the bottom fabric.  I have never sprung any leaks on any of the Static V’s after many, many nights of use.  Whereas I have had to patch 1 hole in the Inertia X Lite and 2 holes in the Inertia X Wave, and there appears to still  be a small leak somewhere in the Inertia X Wave that I need to hunt down.  Every time I have used them outside, they were placed on top of 1.1 oz silpoly, never just against bare ground.  Thus, I’m not impressed with their durability and I would recommend using at least a 1/8″ closed cell foam pad underneath them at all times.  I’m debating actually gluing my Inertia X Lite to a foam pad to ensure that it is always protected and make set-up and storage easier.

I discuss in the video how the 2 torso pads (as well as the full-length Inertia X Frame and Ozone) are designed more for sleeping bag users than quilt users, so that your bottom insulation can loft in the gaps and keep you warm.  However, I have found that wearing my down sweater under my quilt can also take advantage of the loft pockets.  But I still want to have a barrier between the ground and my sweater, which is partly why I want to use a thin ccf pad underneath the torso pad.

I hope you enjoy the video and I appreciate any and all feedback.