TYPES OF CARPET CUSHION
There are three basic types of cushion:
Each type is further subdivided into two or three varieties. Each variety has characteristics that make it useful in particular types of carpet installation. Each variety also has grades, which vary by weight (also called density), thickness, and the amount of force it takes to compress the cushion.
Density is one of the most important parameters of any type of cushion. Density equals weight divided by thickness, and it measured in pounds per cubic foot. All types of cushion can be made dense (more material), or light (more air), or any grade in between, so they can be soft or firm, resilient or supportive, according to the type of room and expected traffic on the carpet they support.
Generally speaking, foam cushion comes in three recognized, clearly different varieties:
Prime polyurethane foam is a firmer version of the same cushioning used in upholstered furniture, mattresses, and automobile seats. Two liquid ingredients are combined to form a large mass of foam, which is then sliced into sheets for use as carpet cushion.
Bonded polyurethane foam (sometimes called rebond) is quite unique. You cannot mistake it when you see it, because it is formed by combining chopped and shredded pieces of foam, in different sizes and usually different colors, into one solid piece. It frequently has a surface net for ease of installation and improved performance.
Bonded foam is one of the most amazing recycling projects of all time. Nearly all the scrap foam in the U.S., and some from other countries as well, is utilized to make bonded cushion. This recycles waste, which would otherwise be thrown out, and it eases the strain on our landfills. Moreover, bonded foam is itself recyclable.
Froth polyurethane foam is made with carpet backing machinery. Liquid ingredients are applied, either directly to the backs of some carpet styles, or to a non-woven material (for making separate cushion). They react and form a thin, dense foam which is particularly useful in commercial applications with wide expanses of carpet.
There are two basic types of sponge rubber carpet cushion:
Waffled rubber cushion is made by molding natural or synthetic rubber. Heat cures the rubber and forms a waffle pattern. This variety produces a soft, resilient cushion whose luxurious feel is particularly useful for residences.
Flat sponge rubber is a firm, dense cushion, which has a flat surface and is normally used in large-scale commercial applications and with loop type (or Berber) carpet.
Rubber cushion manufacturing processes can be varied to produce different levels of density and firmness. The usual measurement is the weight in ounces per square yard.
Reinforced Rubber Carpet Cushions are manufactured with an open cellular structure made from ground tire scrap rubber granules bonded with latex.
Foam and rubber cushions are produced from new and recycled materials. Fiber cushion, on the other hand, uses existing fibers (both virgin and recycled, and either natural or man-made fibers), which are interlocked into a useful sheet of felt. There are two distinct varieties of fiber cushion:
Natural fibers include felt, animal hair, and jute (the material used to make some kinds of rope and heavy burlap bags). This is one of the oldest types of carpet cushion, dating back to the earliest days of machine-made carpet.
Synthetic fibers include nylon, polyester, polypropylene, and acrylics, which are needle-punched into relatively dense cushions which have a firm feel and, as with other types of cushion, can be made in virtually any weight, to stand up under light, medium, or heavy traffic, which is how they are usually classified.
Berber carpet is becoming increasingly popular, and needs a thin, firm cushion. When using this type of carpet, be sure that the accompanying cushion has been specified by the manufacturer as suitable for Berber carpet.
Radiant heating is becoming more widely used in certain sections of the country. In the case of radiant heating, you do not want a cushion that is an exceptionally effective insulator, but one that allows the heat from the subflooring to penetrate the carpet system and heat the room. A relatively thin, flat cellular sponge rubber or synthetic fiber cushion works well under these circumstances. Be sure to ask your customers if their room(s) have radiant heating.