Source: Wikipedia.com
Innerspring Mattresses
Modern spring mattress cores, often called "innersprings," are made up of steel coil springs, or "coils." The gauge of the coils is another factor which determines firmness and support. Coils are measured in quarter increments. The lower the number, the thicker the spring. Connections between the coils help the mattress retain its shape. Most coils are connected by interconnecting wires; pocketed coils are not connected, but the pockets preserve the mattress shape.
Types of Coils
There are four different types of mattress coils:
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Bonnell coils are the oldest and most common. First adapted from buggy seat springs of the 19th century, they are still prevalent in less expensive mattresses. Bonnell coils are hourglass-shaped, and the ends of the wire are knotted or wrapped around the top and bottom circular portion of the coil and self-tied.
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Marshall coils, also called "pocketed coils," are each wrapped in a fabric encasement and usually are tempered, with some adding carbon magnesium. Some manufacturers pre-compress these coils, which makes the mattress firmer and allows for motion separation between the sides of the bed.
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Offset coils are designed to hinge, thus conforming to body shape. They are very sturdy, stable innersprings that provide great support.
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Continuous coils Or Mira-coils, work by a hinging effect, similar to that of offset coils. In a basic sense a continuous coil is simply that, one continuous coil in and up and down fashion forming one row (usually from head to toe) of what appear to be individual coils. The advantages of how firm a support the continuous coil provides it is somewhat tempered with the 'noise' associated from a typical mira coil unit.
Air Mattresses
Air mattresses use one or more air chambers instead of springs to provide support. Quality and price can range from inexpensive ones used occasionally for camping, all the way up to high-end luxury beds. Air mattresses designed for typical bedroom use cost about the same as inner-spring mattresses with comparable features. Several companies currently produce adjustable firmness air mattresses.
Adjustable air mattresses come in a variety of models from basic, no-frills ones that measure about 7" in height, to high-profile, 15" tall hybrids that contain several types of foam, pillow tops, and digital pumps with memory, for individual pressure settings.
Air bladder construction varies from a simple polyethylene bag to internally baffled, multiple chambers of latex (vulcanized rubber) with bonded cotton exteriors. Mattresses have a layer of foam above the air chambers for added cushioning. The air chambers, top and sidewall foam all sit inside a removable two piece cover that looks like the outside of a standard innerspring mattress. These high-end luxury Air Beds are also known as soft sided Air Beds.
Foam Mattresses
Foam mattresses use latex foam or visco-elastic/memory foam instead of springs to provide support. Since foam varies in quality, prices can vary widely. Most name brand mattress manufacturers offer a line of memory foam mattresses.
Flotation Mattresses
Flotation mattresses, more commonly known as waterbeds, primarily consist of two types, hard-sided beds and soft-sided beds. Flotation mattresses are usually constructed from vinyl or similar material.
A hard-sided flotation mattress consists of a water-containing mattress inside a rectangular frame of wood resting on a plywood deck that sits on a platform. Platforms may incorporate drawer systems for storage. Frames may be decorative, with elaborate headboards or tall posts.
A soft-sided flotation mattress consists of a water-containing mattress inside of a rectangular frame of sturdy foam, zippered inside of a fabric casing, which sits on a platform. The effect is to look like a conventional bed and is designed to fit into existing bedroom furniture. The platform usually looks like a conventional foundation or box spring, and sits atop a much-stronger-than-normal metal frame.
Early flotation mattresses and many inexpensive modern mattresses have only one water chamber. These mattresses are commonly described in the industry as "free flow" mattresses. When the water mass was disturbed, significant wave-action could be felt. They needed some time to stabilize after a disturbance. Later types employed wave-reducing methods, including fiber batting and interconnected water chambers. More expensive "waveless" modern flotation mattresses have a mixture of air and water chambers, usually interconnected.
Flotation mattresses are normally heated. Temperature is controlled via a thermostat and set to personal preference, but is most commonly average skin temperature, 30 °C (86 °F).
Futons
Futons are flat are thick with a fabric exterior stuffed with cotton or synthetic batting. Futons are often placed on a configurable frame for dual use as a bed and a chair or couch. Typically, the frame folds in the middle allowing the futon to be used as a couch and flattens to be used as a bed. They are usually filled with foam as well as batting, often in several layers, and are almost always much thicker and larger than Japanese futons, resembling a traditional mattress in size. Futons are an affordable alternative to a standard-size bed and are often sold in sets that include the mattress and frame. Futons normally feature a removable and replaceable cover, giving them more versatility.