Hi sleeperawake,
There are a few posts around the forum that talk about gel memory foams or gel infused foams so I thought I would use your question as an excuse to amalgamate them and create a reference post (that will likely become a page on the site as more information becomes available).
The gel that is used in various gel foams (most commonly memory foams) is a type of thermoplastic polyurethane that is used to change the performance characteristics of the foams they are added to including memory foam but other foams as well. In effect the “gel memory foams” are a sub group of memory foam with similar properties. They have been used for a number of years (and the buckling column gels use the same material in a different form) but were recently popularized by the success of the iComfort, Serta’s successful advertising campaign, and their “showroom feel” which was very successful. The Serta version uses gel “beads” or particles mixed into memory foam. Of course in the mattress industry … when one company is successful with a variation of a material then everyone else will quickly come out with their own version to keep their market share which is exactly what is happening.
Gel is very heavy, strong, and elastic and in the better formulations can add several properties to memory foam including faster response time, conductive cooling properties, phase change properties in some cases, and less temperature sensitivity. The gels can also add some support properties to memory foams (at least compared to other memory foams because all versions of memory foam including the gel versions are too soft to be used as a support layer).
The type of gel added to foams can vary and the percentage of gel added can also vary from about 5% to about 30%. The gel itself is either thermally conductive (like a stone countertop which feels cool to the touch) or phase changing (which stores and releases heat in a specific temperature range) which can both be used to either reduce or regulate temperature for a period of time until the temperatures equalize. You would find that the “hand feel” of most gel foams will be noticeably cooler than regular memory foam (not to the degree of a countertop though) but that depending on the percentage of gel in the mattress they will equalize over time with body temperature at which point the insulating properties of the foam will become dominant. Depending on the amount and type of gel the temperature regulating effect will last longer or shorter over the course of the night. It may be enough to help someone while they are going to sleep or with a greater percentage of gel it could last for a longer part of the night but in general the cooling benefits of gel tend to be somewhat temporary. The cell structure of the foam will also play a major role because gel added to foam that is less breathable and that has a less open cell structure will have little or very temporary benefits because there would be no air circulation to remove the heat it absorbs to the environment.
There are also other types of “non gel” memory foams that have been developed which have many of these same cooling or support properties as well but in the current market environment where every manufacturer is rushing to come out with a gel material to “keep up” with the interest Serta has created … the gel memory foams with these properties can be easier to find and “differentiate”. There is more about some of the different ways that can be used to “cool down” memory foam to help offset its tendency to sleep warmer than other foam materials in post #6 here.
There is also more about the many variables that can affect the sleeping temperature of a mattress in post #2 here.
So gel memory foams are an emerging subgroup of memory foam with similar properties and while they don’t have long term results in real life to show yet … it certainly appears that they have some benefits and some of the feedback on them shows some promise. Like all new materials though … there is lots of hype and exaggeration about gel memory foams in general and they are similar to new generation, cooler, faster response, or more supportive memory foams of other types but there is also “some” substance to the claims. They can make a good choice … especially in the top layers of a mattress where their temporary cooling properties can be more effective or in transition layers (underneath a softer layer) where their greater support properties can be beneficial.
Because gel is heavier than conventional memory foam … adding gel can increase the density of the memory foam that uses it which can make it appear to be higher quality than the base foam before the gel is added. What this means is that the base memory foam before the gel is added may be low density/quality and then the gel can increase the density which makes it appear to be higher quality. In some cases though … adding gel can actually lead to a more durable memory foam because there are some methods of adding gel which can strengthen the base memory foam it is added to. Overall though you can reasonably compare the gel memory foams to the same density of regular memory foam in terms of durability. Some of the different types of gel memory foams includes …
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Gel particulates or microbeads which are mixed into the memory foam itself. These are by far the most common type of gel memory foam in the market. The idea is that the gel particles or “beads” will stay under a person’s body while the memory foam itself “displaces” which can make it more supportive. The particles can also create a more open cell structure which makes it more breathable. The downside to this type of gel memory foam is the risk that the gel particles, like other fillers that are used in memory foam, may actually weaken the cellular structure of the memory foam rather than strengthen it. In this case… the gel memory foam may be less durable than the original memory foam before the gel was added but this will also depend on the size of the particulates. Smaller particulates that are embedded into the cell wall of the memory foam and that have less tendency to migrate out of the foam will be less abrasive or harmful to the cell structure and have less effect on the durability of the memory foam than larger particles that are more inside the cells themselves and will separate from the foam more easily.
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Some are an actual “pure gel” gel material (not mixed with memory foam) which is added in very thin layers on the surface. This is often a “swirl” or “just a touch” on top of memory foam. If it is very thin it is more “label copy” because while the gel may add some small degree of benefit … the layers are too thin to take real advantage of the qualities of the gel material.
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Some are pure gel materials which are poured into holes that have been punched into the base memory foam or into fabricated impressions in the memory foam. This allows for thicker “pieces” of actual gel (as opposed to beads) which can compress more deeply and respond better with weight. This would appear to be a more durable and effective use of the gel (as the “inserts” are thicker and react more independently from the memory foam) as long as the memory foam is also high quality but of course it is still a hybrid memory foam that uses less gel material than a pure gel layer.
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One of the most effective methods of adding gel is actually pouring the memory foam and liquid gel together and in this case the gel becomes part of the structure of the memory foam itself rather than being more of a filler or addition. According to conversations I have had and some testing results … this appears to strengthen the structure of the memory foam and can actually make it more durable rather than less and as I mentioned earlier, changes some of the properties of “pure” memory foam but this type of gel may also soften the foam so it is usually added in lower percentages so the gel itself may have less effect than gel added in higher percentages.
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There are also versions which use thicker layers of pure gel which are laminated onto a layer of polyfoam or memory foam. These use more meaningful layers of gel where the gel itself can act as an actual layer rather than being infused into another foam and has more of the beneficial properties of the gel material itself rather than a combination of gel and memory foam. This is probably the best method to take fullest advantage of the thermal conductive and cooling properties of the gel itself but because the gel material is more expensive … using it this way can also be more costly. This type of gel material is often firmer and is usually only suitable in thinner layers with other layers of softer materials underneath to modify its firmness.
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All of these are different from the “buckling column gel” which is not a viscoelastic material and has completely different properties even though it also uses a version of thermoplastic gel as well.
In terms of durability they will be roughly comparable to “regular” memory foam of the same density … but perhaps slightly less durable.
There will be some “shaking out” yet to happen over the coming years as time will tell how they will perform in real life over the longer term but for now … to a large degree because of extensive advertising and hype and to some degree because of actual performance … they are a popular choice. Post #2 here has more information and links to other posts and information about gel materials and cooling technologies for those that wish more detailed information.
So all in all … gel memory foams are a variant of memory foam that can certainly have some slight cooling benefits (usually temporary when you are first going to sleep until temperatures equalize) and some support benefits and while they are not the answer to all mattress issues that so much of the advertising would have you believe, and there are many other alternative materials and combinations that have similar properties … they are a legitimate material that in it’s better versions can have some beneficial effects on the memory foam they are added to.
Your other two questions are much simpler and I’ll answer them in the next post.
Phoenix
