The terms "padding" or "upholstery" refer to the various soft layers of the mattress that surround the innerspring unit, giving the bed its comfort. Innerspring mattress upholstery contains four essential layers: insulation, cushioning, quilting and ticking.
Insulation is the layer that lies between the coil springs and the cushioning and is frequently constructed from fiber or mesh. The main purpose of the insulation layer is to prevent the outer layers of padding from pocketing into the coils.
Cushioning, also known as "middle padding," lies on top of the insulation and below the quilting layer which tops the mattress. The cushioning layer is key in determining how the mattress will feel against your body. Cushioning can be made from a dizzying variety of materials — the list includes latex, visco-elastic foam (better known as "memory foam"), convoluted foam (also known as "egg-crate foam"), felt, cotton, polyester, non-woven fiber pads, wool, goose down, or even silk and cashmere. Two mattresses with the same innerspring unit can vary widely in comfort, longevity, and price based on how luxurious and durable the cushioning materials are. For example, memory foam will limit how much you feel your partner's movements, and egg-crate foam will create a softer feeling than a flat slab of otherwise similar foam. Likewise, a set with cashmere or silk cushioning will cost a good deal more than one with polyester cushioning. The method by which the padding is stitched into place, known as "tufting," can also affect the durability and price of the mattress. Some of the higher-end models feature hand-stitching, which helps the padding better retain its shape and comfort.
Quilting is the top-most layer inside the mattress. It can provide additional padding, giving the mattress surface a feeling of softness when poked, while also providing a way for the mattress to breathe. Typically, quilting is made of foam and/or fibers stitched to the underside of the ticking. Quilting can vary from quite plush and soft to firm and resilient. Softer quilting will generally have a larger stitch pattern, whereas firmer quilting will be characterized by a tighter, more compressed pattern. A relatively recent innovation in quilting is the "pillow-top," a thick, soft, cushy layer of foam, cotton, wool and/or other fibers that is attached loosely to the top of the mattress. Nipping at the heels of the pillow-top is the newer "Euro-top," which is similar to a pillow-top but is attached more firmly to the mattress. Depending on your preference, special toppers such as these can make a bed significantly more comfortable. That said, be aware that pillow-tops and Euro-tops can compress over time, and as they are an integral part of the mattress, they cannot be replaced.
Ticking, a fancy word for the cover of the mattress, is the protective outer layer of fabric that encases the mattress. Most ticking is made from synthetic fibers such as polyester or a cotton-poly blend, although a number of high-end mattresses now offer ticking in such luxurious fibers as silk or linen. Ticking fabric is typically either woven on a loom (as with damask) or knit. Although you might be drawn in by a snazzy design on the ticking, stitch patterns relate as much to function as they do to aesthetics. As mentioned above, a large stitch pattern will result in a deeper, softer cushion whereas a tighter stitch will provide a firmer, more supportive sensation.