Traditional mattress consists of several layers: top, quilt or ticking layer, comfort or padding layer, coil support system, edge support. Steel coils, being the essential elements of the innerspring, come in many types – Bonnell coil, countinuous coil, tied coil and individually wrapped coil. The overall quality of innerspring and its support is determines by type of the coil, gauge of the coil (thickness of wire - the lower the number, the thicker the coil) and quantity of coils. All better mattresses nowadays use independently pocketed coils providing even support, better contouring of your body, reduced motion transfer and improved durability.
To utilize the entire sleep surface the edge of innerspring mattress is reinforced. Manufacturers use different types of edge support like foam inserts on sides, rows of extra firm coils, border rod around perimeter of the mattress or the most advanced foam incased edge.
The feel of the mattress comes from comfort or padding layers made from polyurethane or premium materials like memory foam, gel foams or latex. The layers come in different thicknesses and shapes and are stacked in certain order to provide a particular feel. They determine the overall softness or comfort of the mattress, what you feel when you push your hand on the top. The amount of padding also determines the model name of the product – firm, plush, pillow top…
On the very top of the mattress are quilting and ticking layers, providing final finish and breathability. Kind of like an insulation layer. High-end products will incorporate natural fibers like aloe, silk or cashmere in these top layers. By federal law all mattresses must be treated with fire retardant materials.
In the past innerspring mattresses were designed to work together with traditional boxsprings containing several bigger springs or tension bars for additional support. For the most part those are not used anymore and majority of modern innerspring mattresses come with solid foundations that don’t alter the feel of the mattress.