How Mattresses Are Made: A Primer For Mattress Shoppers
The concept of the mattress probably reaches as far back in time as petroglyphs found in cave drawings during prehistoric times. A simple nest of of leaves, straw, and animal skins, allowed humans to sleep more comfortably and more soundly than they could have on hard surfaces.
These primitive mattresses could be left in place and reassembled as people wandered from place to place, but as greater numbers of people abandoned a nomadic, hunting existence for a settled, agricultural lifestyle, primitive furnishings, including the bed frame or bed fixture, began to develop.
The development of the earliest mattresses is closely linked with that of the bed frame. In many ancient societies, the bed frame was considered the most significant piece of furniture in a home. Often, it served as the fixture for the central gathering place for virtually domestic activities, such as dining and relaxing, as well as sleeping.
Over the centuries, bed frames became more elaborate and decorative, for those leading luxurious lifestyles, were often intricately carved and fashioned, often with gold or inlaid gems and stones. But despite this, mattresses themselves remained woefully unsophisticated, and unbearable to sit or sleep upon.
Usually, the components of a mattress for a farmer, let’s say, might typically include a sack, filled with straw, corncobs, crop debris, or other gathered vegetation. If you were a person of wealth, the mattress might have been slightly more tailored in shape, and would have included layers of cotton, horse hair, discarded garments or other textile remnants, and significantly less agricultural debris.
Not only were these primitive mattresses uncomfortable, they were extremely difficult to clean, and typically were filled with soil and insects. In either case, rich or poor, the primitive mattress was cheap and made of cast-off remnants that served no other purpose.
Even as recently as the late 1800’s, mattresses were not a whole lot more sophisticated than the debris filled bag from medieval or even primitive times. Once mattresses started to be produced commercially, and with the onset of the Industrial Revolution, mattresses suddenly became more refined.
Deftly hand placed layers of cotton or other plant based ingredients, horse hair, and more refined textiles like linens or other fluffy fibers, were included in the construction of a more vertically integrated design, rather than just being stuffed and scattered about into the ticking, or sack. Often discarded fabric from tailoring shops were sold to high end mattress manufacturers for bespoke mattresses made for high end customers.
It was the invention of a continuous framework of steel coils by German inventor Heinrich Westphal in 1857, that essentially redefined the concept of a mattress, and in 1871, the first commercially made innerspring mattress was introduced in the marketplace.
By placing a set of uniform springs between layers of upholstery, mattress manufacturers could develop consistency in their product so that it had a firm, resilient, However, because so-called innerspring mattresses were initially pretty expensive to manufacture, only cruise ship steamers and higher end hotels that could afford to purchase them.
At the end of World War I, a man named Zalmon Simmons, Jr., who had been an entrepreneur involved in many projects, including the bed frame business, took a crack at improving the comfort of the notoriously firm and rock hard feel of the first innerspring mattresses. He began to produce a line of mattresses that at the time sold for $40, an unheard of price for a home furnishing of any kind.
Simmons’ coil systems were stabilizing woven coil mats were typically about 8” tall, had a wire wrapped exterior perimeter which was perfectly rectangular, and could be made in several sizes. At first the steel used was hand woven, but as machinery was developed to twist the wiring, a complete unit could be machine made very rapidly, and an assembly method of placing the layers around the woven coil mat made mattress making profitable. It also meant that the innerspring mattresses was available even to people of modest means.
As the Simmons company progressed and refined their designs to include tufting and padding, their products became increasingly more comfortable and affordable, and Zalmon Simmons’ son Grant marketed the mattress line effectively getting his mattresses into the White House, and onboard the first Air Force One. They remain a giant in the mattress industry to this day, after enduring many hard times through multiple family generations.
First, through a number of enhanced innerspring designs, modern coil type mattresses changed dramatically. The one piece woven coil “rack” style piece was notorious for transferring motion and waking your partner, so new innovations such as individual pocket style coils that are individually placed became the new design standard used by many manufacturers, including another industry pioneer, the Leggett & Platt Company, who supplies coil components to many large scale mattress fabricators.
How A Mattress Is Made
The central component of a typical coil type mattress is the innerspring unit, a series of wire coils that are attached to one another with additional wire built in a sequential, cage like format. The upholstery layers are affixed with wires or clips to the innerspring unit, usually beginning the first layer, called the insulator, which is attached directly to the coil units and which keeps the next layer, called cushioning layers, imprinting on and molding to the coils.
While the insulator is fairly standard, the number of cushioning layers can vary widely in number, ranging from two to eight layers and from 1/4 inch to 2 inches (.63 to 5 centimeters) in thickness. Moving outward, the next component is the flanges, connecting panels that are attached to the mattress’s quilted cover with large, round staples called hogs rings. The top, bottom, and side panels of the mattress are stitched together with border or edge tape.
The comfort layers can be a variety of foam layers, which can be polyurethane foam, memory foam, latex, even plant based foams made from soy and other green and eco-friendly ingredients.
While a wide variety of springs are designed to accommodate special needs and situations, the four most commonly used coil units are the Bonnell, the offset, the continuous, and the pocketed coil. The Bonnell springs are hourglass-shaped and knotted at both ends. The offset design is similarly hourglass-shaped, but its top and bottom are flattened to facilitate a hinging action between the coils.
The continuous innerspring consists of one extremely long strand of steel wire configured into S-shaped units. Finally, in the pocketed coil unit, each coil is encased in a fabric casing that also connects it to neighboring coil-casing units. The pocketed coil system is now the most popular form of coil mattress insert in the business today.
A typical mattress contains between 250 and 1,000 coil springs, and mattresses that use fewer coils normally require a heavier gauge of wire. It is not uncommon for an innerspring unit to require as much as 2,000 linear feet (610 meters) of steel wire. The individual coils can be joined in several ways. One common method is to use helicals—corkscrew-shaped wires that run along the top and bottom of the springs, lacing the coils together. Rigid border wires are sometimes attached around the perimeters to stabilize the unit.
Most manufacturers also manufacture foundation pieces ( often called boxsprings) that lie directly beneath the mattress, resting on the frame of a metal or wooden bed. One of the most common types of box spring foundations uses a spiked coil configuration, in which the springs are narrow at the bottom but spiral to a wider diameter at the top. While a spring system provides the most common type of boxspring support, torsion bars are also sometimes used. Other foundation mattresses contain no springs at all but consist of a built-up wooden frame.
The Raw Materials
Mattresses are presently made of many materials, both natural and synthetic. The innerspring, helical, and boxspring components are made from wire; the boxspring wire is usually of a heavier gauge than that used in the innerspring. The insulator consists of semi-rigid netting or wire mesh, and the cushioning layers can comprise a number of different materials including natural fiber, polyurethane foam, and polyester. The flanges are made of fabric, and the hogs rings of metal. Top, bottom, and side panels consist of a durable fabric cover quilted over a backing of foam or fiber, and the binding
Once the completed innerspring unit is received, workers manually apply the insulator layer. Next, they apply the cushioning layers that will determine the feel and comfort of the final product. These layers can be made from a variety of foam layers and arranged in different sequences, different thicknesses and densities, all with the intention of creating a unique “recipe” for the mattress being designed. A particular mattress may have specific applications, perhaps as a firmer mattress, or a softer variation.
Meanwhile, the decorative ticking, encasement, or outer covering that will serve as the exterior for the top, bottom, and sides is made on a giant quilting machine, which controls a multitude of needles that stitch the cover to a layer of backing material.
The underlying boxspring may consist of either a wooden frame with slats or of metal coils similar to those used in the mattress itself. The boxspring may be upholstered, but, even if it is not, it always receives a fabric covering.
In the late 1980’s a new kind of mattress emerged and became commercially popular. Largely pioneered by the Tempur-Pedic Company, an all foam mattress design that did not include springs or coil elements, became hugely popular.
Foam Mattresses: Tempur-Pedic Was Developed From A NASA Project
The very first memory foam material was developed by NASA in the 1970s. Their intention was to try to improve seat cushioning and crash protection for airline pilots and passengers. Memory foam has widespread commercial applications, in addition to the popular mattresses and pillows you are familiar with today.
Anybody who has gone shopping for a bed, a new pillow, or even a new bicycle seat or mouse pad wrist rest in the last twenty years will be familiar with memory foam. This new material has been applied to a huge range of uses since its introduction to the US in 1991—from revolutionary medical uses like burn unit bedding to gimmicky new product designs. In fact, the original material has been knocked off by many companies who created their own variations of the material, and it is found in hundreds of mattress designs and options. But what is it, who came up with it, and how does it work?
Though it is a relatively recent invention in the U.S., memory foam has been around in various forms since the midpoint of the century—the first work on the polyurethane polymers that are part of the memory foam recipe which give it the unique melting sensation that it offers, was actually begun in 1937 by Otto Bayer and his coworkers.
In 1965 the nursing staff at Lankenau Hospital in Wynnewood, Pennsylvania, tested polyurethane pads for use as bedding material, and found that they prevented “decubitus ulcers” (also known as pressure ulcers, or bed sores, sustained by patients who spend long amounts of time in bed), and found them to be hypoallergenic and resistant to bacteria. In the 1960s, NASA did work on materials that would serve as better cushions, and would also keep astronauts comfortable and protected from the extreme g-forces of lift off.
Memory Foam vs. Polyurethane Foam: The Two Common Ingredients Of Most “Bed In A Box” Mattresses
Memory foam, which is essentially urethane foam, starts its life as polyurethane foam—a material first manufactured in the mid 1950’s by adding water, halocarbons, or hydrocarbons to a polyurethane mix. Depending on the chemicals added and the way it is processed, polyurethane can form anything from car parts to spray liner, or in this case, an extraordinarily comfortable sleeping surface recognized the world over.
In the modern production of memory foam, a compound called polyol is mixed with a di-isocyanate and water. The foam becomes to froth, and rises like bread, and forms an open cell structure that helps give it its unique ability to spring back slowly from pressure. The introduction of bubbled gases into the initial solution creates a matrix that allows air to move from cell to cell; vary the application of chemicals and the amount of gas infused, and the size of the bubbles changes. A more open cell structure will have more give, and allow more airflow through the material.
The firmness of memory foam as well as polyurethane foams is rated by a unit of measurement called IFD (Indention Force Deflection), otherwise known as ILD (Indentation Load Deflection) measuring the force in pounds required to make a 25% indentation in a 4 inch thick foam square.
Also important in measuring the “softness” of a foam is the density of the foam, which gives the foam a firmer or softer feel. Foam densities range from 1-7 lbs, but a foam of decent quality for mattress construction will usually be at least 4 and ideally 5 lbs. A foam with a high density, but low ILD may still feel firm when compressed, especially in a lower room temperature. The density together with the IFD/ILD and the resilience will determine the softness, firmness, and life-span of the foam.
Foam that is lower density will more readily conform to pressure, whereas higher density foam (usually 5-lb. or above) molds itself to contours when warmed by body heat. Major production of memory foam did not begin until NASA released it into the public domain in the 1980s. Fagerdala World Foams began producing this somewhat difficult product in full mattress sizes using specialized molds, and in 1991 produced the first “Tempur-Pedic Swedish Mattress.”
Today numerous companies around the world produce visco-elastic memory foam, which gives consumers increased variety and price range. Unfortunately, it also increases the risk of purchasing cheaply-made foams that may deteriorate over time. Not all memory foam is created equal, as many of the overseas manufacturers work at reducing the cost of memory foam by adding in other “filler” type ingredients that reduce the quality and potentially add toxicity to the formulation.
mattress industry Trends
Currently, the consumer demand for mattresses is fairly consistent. In 1990, approximately 16 million mattresses were sold in the United States. Together with foundations, mattresses accounted for about $4 billion in retail sales. With the exception of a few large companies, most mattress manufacturers are fairly small, community-based operations. Of the approximately 825 mattress factories across the United States, most are still owned and operated by the founding families.
In 2020, most mattresses are manufactured according to standard sizes. This standardization was initiated by the industry to resolve any dimensional discrepancies that might occur between companies that manufacture beds and companies that make mattresses. The sizes include the twin bed, 39 inches wide and 74 inches long; the double bed, 54 inches wide and 74 inches long; the queen bed, 60 inches wide and 80 inches long; and the king bed, 78 inches wide and 80 inches long.