Innerspring Mattresses
When you think of a mattress, you are likely picturing a traditional innerspring mattress. While many of these styles have similar exteriors, inside there can be significant differences. The basic innerspring mattress components are Coils, Upholstery and Foundation.
Coils
The "core" refers to the supportive layer of a mattress formed by internal coils, or springs. These coils provide the main support underneath your body. Good support is essential for a good night's sleep and for maintaining spinal alignment. When evaluating different mattresses, be sure to consider the number of coils present in the mattress, the construction technique, and the shape of the coils. These factors determine the overall comfort and support of the mattress.
Coil Count
Coil Count refers to the total number of coils in a mattress. The minimum number of coils you should look for is 300 for a Full size, 375 for a Queen size, and 450 for a King size.
Coil Construction
Gauge: "Gauge" refers to the thickness of the wire used to construct a coil. The lower the gauge, the thicker and heavier the wire. The higher the gauge, the thinner and more "springy" it is. Low-gauge coils provide a firm mattress and high-gauge wires give a softer feel.
Working Turns: "Working Turns" refers to the number of times your finger can travel 360 degrees around the coil. Each 180 degree turn is one working turn, while a 360 degree rotation equals two working turns. Mattresses that contain coils with a high number of working turns provide a softer feel. Also, high numbers correlate with durability since your body weight is supported by a more tightly wound spring.
Tempering: During production, coils are "tempered", or heated and cooled. This process helps ensure they retain their original shape and height after compression. The coils may go through the tempering process more than once to provide increased durability and resistance to sagging.
Coil Design
Hourglass Coils: Hourglass coils come in two varieties: Bonnell and Offset. The design of the Bonnell coil is primarily based on the springs found in buggy seats during the 19th century. The most prevalent coil in the mattress industry, its hourglass shape is knotted at each end. Offset coils feature a design similar to Bonnell, but the design has flat circles at the top and bottom of the coil to create a hinging action. This allows the mattress to conform more to your body shape.
Pocketed Coils: Sometimes referred to as Marshall coils, these coils are individually wrapped in a fabric pocket. Because each coil moves separately from the others, this construction method provides more motion separation (the degree in which movements on one side of the mattress can be felt on the opposite side). Mattresses incorporating this method are ideal for restless sleepers. An additional advantage is that the pocketed coils absorb weight individually and can take greater stress, therefore providing increased durability over time.
Continuous Coils: Continuous coil springs are loosely S-shaped spirals made from a single length of wire. Each coil is attached to the adjacent coil, making the entire core stronger and more stable. Continuous coil mattresses have significantly higher coil counts than styles with non-continuous designs, making it difficult to compare the coil-count aspect to other models.
Foundations
Innerspring mattresses require a foundation to work in conjunction with the mattress to enhance its support and durability aspects. Selecting a foundation is just as important as choosing the mattress itself.
Box springs are most often sold with mattresses as a set. A box spring is a wooden box that contains heavy coil springs. The purpose of these sturdy springs is to offer additional foundational support so the mattress doesn't have to absorb the full weight of the sleeper(s). This adds longevity to your mattress.
Split box springs are standard with all King and California King mattresses and are now an option with Queens. Split box springs come in two pieces and are therefore ideal if you anticipate having trouble fitting a box spring up stairs or through a narrow hallway.
Box springs have also become available in a low-profile option. These extra-thin versions are designed to accompany today's thicker, plusher mattresses. Standard box springs are 9" in height and low-profile options are usually 5"-6" tall. The lower profile of the foundation prevents the sleep surface from being higher than a traditional sleeping surface.
In addition to box springs, another type of mattress foundation is a torsion module. This version features heavy bars wrought at a 90-degree angle for support. There are also slatted bases, sometimes called built-up foundations. These feature wooden slats that go across the frame of the foundation unit. Slatted bases provide the firmest support of all foundations and can also be used with foam mattresses.
Upholstery
"Mattress upholstery" refers to the soft layers of padding and fibers that top the innerspring core, giving the mattress its comfort element. Innerspring mattress upholstery commonly contains four layers: Insulation, Cushioning, Quilting and Ticking.
Insulation: Insulation refers to the fiber layer that lies between the coils and the cushioning. This layer does not trap heat. Its purpose is to prevent the outer layers of cushioning from sinking down in between the coils with use.
Cushioning: The cushioning section is above the insulation but below the quilting layer. This layer is home to the comfort that your mattress gives you. Cushioning can be memory foam, latex, convoluted, or "egg crate" foam, felt, cotton, polyester, wool, goose down or even silk and cashmere. The comfort of your mattress depends almost singly on the layers of cushioning, their quality and durability.
Quilting: The quilting layer tops the inside of the mattress. It provides some additional padding while also providing a way for the mattress to breathe. Quilting is generally made of soft foam and/or fibers that are attached to the underside of the ticking. Make note of the size of the shape the quilting creates. A larger stitch pattern will have a softer feel with more give, while a tighter stitch pattern will be firmer. Types of quilting can range from a standard surface to the plushest of pillow tops.
Ticking: Ticking is another name for the cover of the mattress. This is the outermost layer that encases and protects the mattress. Ticking fabric is usually made of synthetic fibers or a blend of synthetic and natural fibers. Often mattress ticking is a smooth, woven damask pattern with a tonal design. Keep in mind that the stitch pattern on the surface of a mattress can affect the way it feels when you lie on it. As with quilting, a larger stitch pattern will have a softer feel with more give, while a tighter stitch pattern will be firmer.