Anatomy of a Mattress
Conventional Inner Spring
How many springs and what gauge of wire? The number of coils in a mattress ranges from 312 to over 800 with metal inner spring mattresses. Normally heavier gauge coils will provide for a firmer support with fewer coils. The thickest gauge normally available is 12.5 while the thinner gauges are in the 14 to 15.5 range. When you have thinner coils it is important to have more coils in the mattress since the coils give easier.
Pocket Coil or an encased coil, or encased spring,(most commonly known in North America as "pocketed spring”) is a component part of a mattress in which each coil is separately wrapped in a textile material. Encased coils may also be generically referred to as Marshall coils or wrapped coils. Marshall coils were created by English-born James Marshall in 1900, when he settled in Canada. In 1901, he sold the rights to this design to English mattress maker VI-Spring. He received a Canadian patent for his unique invention: Marshall established the original Marshall Mattress factory to produce his mattresses in Toronto, Ontario. Marshall conceived of a mattress whereby internal independent springs would provide both support and comfort within the mattress itself. Marshall produced pre-compressed cylindrical coil springs, each sewn inside an individual cotton fabric pocket, which provided uplifting support on its own. When fitted together, the coils became an independent suspension system that contoured to each person's form and weight, providing unsurpassed support and comfort. When upholstered, a finished Marshall mattress not only reduced physical pressure under the sleeper, but actually relieved it as well. Consequently, Marshall's pocket spring-filled mattress system became the original worldwide standard for spring-filled mattress construction and would continue to shape the next century in mattress design. Many other manufactures also now use the pocketed coil, but each manufacturer is different.
The edge of the mattress can be one of the first places where it will show wear, since it receives the most concentrated compression as you get into and out of the bed. There are several types of edge support systems that are used to reinforce and support a mattress over its lifetime. The first is a foam perimeter which encircles the mattress body with 3 to 4 inches of high density foam. Some of the manufacture space there coils closer together at the edge for additional support. Space clips and edge guards are another option, and are used on the perimeter traditional inner spring mattresses to keep the coils from collapsing overtime. Another option, in the more advanced mattresses, would be the outermost coils are thicker gauge metal, which gives better edge support.
Today there are various types of specialty materials that will help with different needs.
Latex, memory foam, gel, cashmere, silk and wool are just to name a few.