The Mattress Dictionary

The Mattress DictionaryThere are a lot of terms thrown around in the mattress industry. So we thought a starter mattress dictionary with those we get the most questions on would be helpful. Let us know if you’d like to see others!

Bio-Based Foam
A flexible foam in which a portion of the petroleum-derived polyols has been replaced with plant based oils such as soy, castor, canola, rapeseed, sunflower or palm. This content typically ranges from 5% to 20% of the total polyols in the foam.

A knotted, round top, hourglass-shaped steel wire coil.  When laced together with cross wire helicals, these coils form the most basic innerspring unit.  The finished unit is also referred to as a Bonnell.

Coil Count
The number of coils in an innerspring unit. When specifying an innerspring unit, the coil count is usually designated by the number of coils in a full-size unit of that model or series. Example: a “312 Bonnell” innerspring has 312 coils in the full-size and proportionately larger numbers in the queen and king.

Continuous Coils
An innerspring configuration in which the rows of coils are formed from a single, continuous piece of wire.

Convoluted Foam
Foam that is specially cut to produce a surface with dimples, available in a variety of shapes including egg carton-like designs, waves, squares or sharply defined points.

A measurement of the mass per unit volume, measured and expressed in pounds per cubic foot (pcf) or kilograms per cubic meter (kg/m3). Foams are most often discussed in terms of their density.

A tightly coiled, elongated wire used to join individual coils to each other in an innerspring unit.

Coils that taper inward from top to middle and outward from middle to bottom, resembling an hourglass in shape. They are typically employed in Bonnell and offset coil designs.

Latex Foam
A flexible foam created from a water dispersion of rubber, either from the rubber tree (natural latex) or a manufactured product (synthetic latex) or a combination of the two. Latex foams are not chemically related to polyurethanes.

An unknotted offset coil with a cylindrical or columnar shape. An LFK innerspring unit is generally high coil count and uses high/thinner gauge wire.

Memory Foam
See Visco-Elastic.

Offset Coils
A coil design on which portions of the top and bottom convolutions have been flattened to facilitate hinging action between coils. Offset coils with unknotted wire at the top and bottom are called “open offset.”

Pocket Coil
A type of innerspring construction in which thin gauge, knotless coils are encased in fabric pockets. Also known as Marshall coils.

An indicator of the surface elasticity or “springiness” of foam, measured by dropping a steel ball onto a foam cushion and measuring how high the ball rebounds.

Wire Gauge
The diameter of the high-carbon steel wire that is used in innerspring constructions. Wire is typically furnished in 12.5 to 18 gauge for bedding industry applications. The higher the gauge, the thinner the wire.

Tempered Steel
Steel for use in coil springs is treated with heat to reduce brittleness, a process employing electric charge, oven heat or both. The finished innerspring unit is also heat-tempered, or “stress relieved,” to restore original coil characteristics after assembly.

A common term for polyurethane foam but actually a misnomer. Urethane is a colorless, crystalline substance used primarily in medicines, pesticides and fungicides, not in the production of polyurethane foams.

Visco-Elastic Foam
Slow recovery polyurethane foams that are temperature-sensitive. They conform to body shape and, by doing so, increase the amount of surface area, reducing surface pressure. Also known as “memory foam.”

photo credit: Muffet via photopin cc

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