Gel is a recent newcomer to the mattress space. It is being used as both a standalone layer and an infusion into foam. Gel benefits mattresses by retaining less heat than memory foam. Also, newer gels compete against memory foam by being more responsive and less toxic.
Gel is similar to foam because it is a polymer made by blending plastics and other chemicals.
Because of gel's heat diffusing properties, it is generally found in the top layer of the mattress under the cover.
Pros: Cooler sleeping surface vs memory foam. More responsive feel when not combined with foam.
Cons: Similar to foam, it is a synthetic blend of chemicals.
Overall Score: 8.6/10
General Support: 9.5/10
Price Value: 9.2/10
Each gel is a different proprietary blend of chemicals. Similar to foam, there are chemical reactions, blending and heating of the plastics followed by cooling and molding. For gel infused memory foam, the gel layer is added to the memory foam prior to cooling so that all of the benefits of the gel are absorbed into the memory foam.
Generally, gel is used in combination with foam to provide a cooler and more responsive sleeping surface.