History and Evolution of Mattresses
It is hard to believe that the concept of a mattress or bedding predates the human race. Archaeological findings from Sibudu rock shelter in South Africa dating approximately 77,000 years ago, much before the advent of Adam and Eve, have revealed the existence of three feet by six feet ‘mattress’. This mattress consists of many layers of rushes and reeds, and it was found below bedding made out of compacted leaf plants and grasses. The bedding was found to have accumulated in a cave over 39,000 years, with the oldest one dating as far back as 77,000 years. The study leader Lyn Wadley from the University of Witwatersrand in Johannesburg has described this mattress as being 50,000 years older than others discovered at other archeological sites across the world. Evidence points to the burning of the bedding periodically, most likely done to eliminate the effects of garbage and pests (Owen, 2011). The mattress had built-in pest control as well. It was made out of leaves of a tree called Cryptocarya woodii, which has got aromatic leaves which contain mosquito-killing insecticides (Wayman, 2011).
Historians suggest that while earliest hominids slept on tree branches to keep themselves protected, probably the first hominid who slept on the ground might have been the Homo Erectus sometime around 1.89 million years ago. They also suggest that this shift could have occurred due to the discovery of fire and the ability to control it. The flames could easily keep the predators away. As Homo Erectus became taller and bigger, the adaptation from trees to the ground was more or less complete. While there is nothing in the paleontological record that points to the use of any type of bedding or mattress by the Homo Erectus, it is known that Neanderthals built grass beds as evidenced by the discovery in a cave site in Spain dating sometime within 53,000 to 39,000 years ago. From that time on, beds are reported to have gone through an evolutionary process (Wayman, 2011).
Mattress and the Ancient Egyptians
In the post-flood period after Noah, the invention of the raised bed has been credited to the Egyptians. It was very important for people to protect themselves from crawling insects or even other reptiles like snakes and lizards, etc. and it was important to sleep a bit above the ground to ensure that such creatures will not have easy access to the human body at night. The ancient Egyptians, therefore, came up with the idea of a raised bed. They are known to have used items like carpets, rugs, garments, and even wool as materials to build the foundation or fill the mattress. The use of wool was related to the influence of the Greek people on the Egyptians, as many Greeks had moved into Egypt during the Ptolemaic Kingdom. The use of wool influenced the lifestyle of people during that period.
Woolen Mattresses on Wooden Beds
The Egyptians are known to have made raised beds. They had intriguing structures, as many were slanted from the headboard towards the footbed. They even had a footboard to make sure that the sleeper would not roll over the bed and slip down. Many of the beds had side rails as well, stressing the fact they wanted to ensure that they stay on the bed throughout the night and not fall from it. Most of the beds had legs, and these, unlike the single braces used these days, were more like animal legs. They often used gazelle-like or even heavy bull-like legs. The legs also had hooves like endings, and some were in the form of a paw or claw-like the felines. The mattress, the Egyptians used on the bed, was made out of reeds, plaited strings, or even with wooden slats. These supports had women cushions on them, and in other cases, they used some other soft material to provide comfort and to cushion. Linen was the material Egyptians used as sheets. (Springer, 2019). Indeed, Egyptian Kings, like Tutankhamun, had all the provisions available for luxury beds, which were made out of ebony and gold. Still, the general public also employed raised mattresses made out of palm bows, and they were heaped in one corner of their homes.
Mattress/Bed and the Israelites
Easton’s Bible dictionary mentions that the Jewish bedstead used to be in the form of a divan or a type of platform that was placed around the side of the house. This used to be in different shapes. At times, it would be merely a mat; at other times, it would have one or more quilts. Sometimes, it would be in the form of a portable frame. The dictionary also provides information on how the bed chambers were. The elevated platforms used as beds and overlaid with a mattress were usually at the upper end or along the sides. According to (2 Kings 4:10; Ex. 8:3; 2 Kings 6:12), this was the general arrangement for the male members in a family and also for guests. However, there would be other bed chambers with a distinct private character. In another revised version, the bed-chamber is also considered as a place where mattresses were stored. (Mathew, 1897).
Mattresses and Ancient Greeks
It is clear that even during ancient times, the beds were made out of hard materials like wood or iron, and the mattresses on top of them were made either of wool or other soft materials. When archaeologists dig, they are likely to find the beds in some form, but since the mattresses were made out of perishable materials, they are usually not excavated. The same holds for the mattresses or the soft material that was used for cushioning the beds during those times. A lot of funerary beds have been excavated from places like Macedonia, which are either made of stone or wood and were used in funerary. Experts have been studying the possibility of getting an idea from them about the beds that were used in houses (Hesperia, 2006). However, as the Greek people often used wool and their entry into Egypt also gave way to woolen mattresses ion Egypt, it can be deduced that wool must have formed a part of the material they used as the soft cushioning on wooden beds.
Beds with Mattresses for both Sleeping and Meals
Experts believe that the funerary beds were covered with mattresses, cushions, and pillows even. The mattresses were also carved and throw light on the Hellenistic bed furnishings. An oil painting found in the 4th-century B.C. tomb III at Ayios Athanasios shows such furnishings. It depicts six symposiasts who are reclining on beds, which have got colorful covers. The symposiasts have their hands rested on pillows, and they are seated on soft mattresses. The colors of the sheets and the pillows even matched. They are shown in front of the meal table. Many experts believe that during the Greek period, the beds with soft mattresses which were used at the time of meals were also the same beds on which people slept.
Evidence of Mattresses from Literature
It is not just the excavations and the paintings from the Ancient Greek period that give evidence of the mattresses that were used in their culture. There are many pieces of evidence available ion literature as well. In Athenaios, there is a description of sweet-smelling or rose-fragranced covers. Mattresses are described as being made out of linen, wool, animal skin, dry leaves, or even feathers. Of these, the dry leaves, wool, and feathers were used as fillings. As far as the archaeological evidence of a mattress is concerned, a substance that could be feathers or wool was found in the Tomb of Philip at Vergina. It is considered to be the remains of a mattress or a pillow (Hesperia, 2006). Thus, plenty of evidence from the ancient Greek period suggests the use of soft mattresses on beds.
Mattresses and the Romans
The beds were considered as defining pieces of furniture in the ancient Roman era. The materials used in the construction of the bed, as well as the mattresses and bedding, have been studied extensively by scholars. Latin texts give lots of information on the sleeping and reclining g habits, which were quite versatile as well as elaborate. The types of the bed, along with the mattresses, ranged from the simple camp bed (grabatus) all the way to the super-luxurious furnishings that were used while sleeping or even while reclining for dinner. The Roman bed was known by many different names, and these included grabatus (and its variants), cubile, Torus, lectus, and lectulus. These are all synonyms, however, with some differences. The Roman bed served as a multifunctional piece of furniture. It served as a place to sleep, to make love, and also for other activities such as dining and even for pursuing literary activities (Nissin, 2016).
During the Roman era, it is now known that even people who had humble means owned beds as well as mattresses. The bed, even though an ordinary kind, had legs as well as a frame. These beds, however, were not easily portable. It is very rare to find evidence of the use of pallets and mats for sleeping during the Roman era, as evidenced in the Roman literature. Pallets were most likely used by slaves. However, this has not been noted down in the literature produced by upper-class writers of those times. The seasonal effects on the bed and mattresses cannot be overlooked either. Due to the humid Italian winters, the beds needed to be raised above the ground, and the use of appropriate mattresses was a must. Although the moralists during the Roman era did not like the concept of luxurious bedding and despised luxury to favor austerity. Yet, comfortable and luxurious bedding and mattresses were favored in that era (Nissin, 2016). It is evident that without a comfortable and luxurious mattress made out of textiles and other soft materials, the beds could not have been luxurious. However, in ordinary people’s houses, who could not have afforded the luxury, straw-stuffed mattresses were likely used while the slaves slept on mats and pallets.
A Typical Roman Bed for the Rich
A typical Roman bed used by nobles was closed on one side with a board (pluteus) while on the other side, it was kept open (sponda). The legs of the bed were wooden, and these were richly decorated with gilded bronze plates as well as ivory. The corners of these beds were usually embellished with the heads of satires or cats. Mattresses are known as Torus as well as pillows used to be stuffed with many different materials like wool, straw, leaves, or even cheap feathers from duck, chicken, or goose. The effect of leaves on human health was considered beneficial in terms of human health. The leaves were also used to pull away from the parasites. Leather straps were used to hang the mattress, and the pillows had beautiful embellishments at ends. The bedding on these beds used to be made out of hemp or wool. In even richer homes, there were quilts and blankets as well. Purple was a popular color, and sewn gold patterns were common. The wealthy Romans also used curtains to keep dust from getting to the beds and the mattresses. Despite, all the luxuries described here, experts believe that the Roman beds were not as comfortable as the modern beds that exist today (Romanum, 2020).
Other Royal and Ordinary Beds and Mattresses in Ancient Times
Research on the Assyrians in ancient times suggests that the royal bed consisted of a mattress along with large and rounded pillows as well as cushions and coverlets. However, as far as the ordinary people are concerned, they only had mattresses, and as researched by experts, they were raised slightly on one side and aptly fitted into the curvature of the arm. This acted as a substitute for the pillow. This feature likely provided the poor laborers with the sort of comfort that the rich would get on their luxurious pillows (Rawlinson, 2018).
The Persian Innovation
The Persians as far back as 1,600 B.C. are credited with the invention of the water bed or mattress, which consisted of goatskin filled with water. This was a watershed moment for luxury sleeping and in terms of the development of the mattress, which the Egyptians had already made a part of their lifestyle. Waterbeds offered the kind of comfort, which was not easy to achieve with other materials. It was a revolutionizing concept as it involved the use of a ‘fluid’ rather than soft materials as filling for the mattress. It was, therefore, the Persian royalty who were the first people to have slept on water beds (Horne & Horne, 2006).
Mattresses and the Byzantine Era
In Byzantine literature, sleeping equipment such as rugs used in place of pallets or mattresses, or even cushions themselves are mentioned along with blankets, covers, etc. which were made out of wool. There is mention of animal fur or even fake animal fur. There are mentions of quilts filled with wool as well. Some were covered with silk. Silk covered pillows are also mentioned. Sleeping equipment and materials like these used to be second in worth after jewelry in a Byzantine household. Often, there used to be curtains and canopies which would hang from the ceiling and were used to protect from the insects or sometimes for privacy. Amazingly, in some accounts pertaining to the 12th and 13th centuries, beds appear in the literature, which could be disassembled and stored away. These were always used with mattresses. Such beds, according to the accompanying documentation, were to be used exclusively either for the sick or for visitors and, more specifically, for important visitors. It appears that during the Byzantine times, beds and mattresses in combination were present in all the royalty and within all noble households (Oikonomides, 1990).
Ordinary People Homes During the Byzantine era
The ordinary homes were familiar with beds as well. The saints of the 12th century, as well as the ascetic monks and other people, often used a mattress or a prayer or sleeping rug. Animal skins were also used as mattresses. Pallets were also used. However, these were used primarily for the sick. Many ordinary people put the mattress directly on the floor at night and put away the mattress during the day. 10th and 11th-century Byzantine texts speak a lot about high mattresses made out of wood or sometimes even stones with softer materials on top. It appears that the main idea of hard material at the bottom and soft material on top related to the concepts of comfort and support provided by the mattresses (Oikonomides, 1990).
Mattresses During Medieval Times
The late-medieval ‘materas’ does not really resemble the modern mattress. Terms like ‘fetherbed’ and ‘matrasse’ are common in wills from the 15th century. However, they do not resemble the featherbed or mattress of today. However, it appears that these two items went together as a pair. Experts believe that the mattress was an essential component of the bed. However, the featherbeds were rather luxurious additionals. Fourteenth-century accounts mention Dukes in England sleeping on featherbeds. ‘Standard Materas’ was probably the essential mattress required for the bed. The featherbeds were usually stuffed with clean down without the scalded feathers. Mattresses, on the other hand, had wool. By the late Middle ages, the featherbeds were stuffed with soft materials, while mattresses were quite firm. As time passed, mattresses became more and more stuffed and were more and more used to lie upon rather than to be used as unstuffed coverings. Featherbeds were similarly used but were an alternative to the mattresses as they were filled with clean down (Louise & Morgan, 2014).
Mattresses During the Renaissance Period
There is no doubt that the royalty and the nobility enjoyed the best of beds and mattresses that filled with soft materials or down, and so did other wealthy individuals. However, during the Renaissance period, the ordinary people slept on mattresses that were made out of straw, feathers, and pea-shucks, and these were stuffed into coarse ticks. All of these were then covered with brocades, velvets or silks. One can imagine that these mattresses would have been highly vulnerable to bugs, especially in view of the fact that during those days, it was normal to have scorpions, varmints, snakes, roaches, and other creepy creatures invading people’s homes (Tucker, 2018).
Mattresses and Beds for the Rich
As far as the rich and the endowed were concerned, their beds and mattresses, even before the Renaissance period, i.e., by the 14th century, had become highly ornamented. Such Embellishments had become an integral part of the bed. The beds started to be covered with hangings of very rich and exotic materials such as velvet, silk, and gold cloth. From the 14th century to the 17th century, the size of the bed for the wealthy kept increasing. The fillings were primarily of wool in the mattresses, and the featherbeds had down fillings. From the 17th century onwards, the beds became magnificent and even enormous. The start of this period is often termed as the magnificent century for beds. As a piece of furniture, the foundations acquired prime importance in European culture and homes. During this period, portable beds were also introduced and, along with them, the appropriate mattress as well. The French aristocracy was the most passionate about magnificent beds and accompanying mattresses. One such enormous foundation was built for the Palace of Versailles, and it had so much embellished gold that the velvety part and the bedding were barely visible. (Swanich, 2012).
The Advent of Mechanical Technology and the Invention of the Spring Mattress
Since time immemorial till the end of the 19th century, the evolution of the mattress had been more or less linked with the type of materials that were filled into the mattress to get the firmness level desired and make them comfortable for sleeping in the night. However, during the Renaissance period and in the following years of the industrial revolution, technology started to make its mark on a lot of objects that were used by people. The mattress was no exception. Mechanical technology, which was the primary mode of technology during the industrial revolution, had a direct bearing on how the mattresses were designed. In the year 1871, a German inventor Heinrich Westphal was the first one to introduce mechanical spring technology into his mattress design successfully and came up with the very first spring mattress. The invention was based on the idea of combining comfort and support. Westphal fully understood how the mattress provided comfort and support to the sleeper. He knew that the soft materials on the top of the mattress give the cushioning required which increases the plushness or the comfort level for the sleeper while the bottom part of the mattress has to provide the support that was usually provided by the beds traditionally as a result of being made out of hard materials such as iron, wood or even stone in the past. He became up with the brilliant idea of utilizing mechanical springs under the soft mattress top to provide the necessary upward bounce, which could balance and neutralize the gravitational force, which tends to bring the body downward.
Thus, the very first technology-supported mattress was invented in 1871. However, no one took the invention seriously. Perhaps the consumers were not attuned to the idea of using technology-supported items in their bedroom by that time, and the bed and mattresses kept being manufactured using wood, iron, etc., while the soft mattress materials remained wool, feathers, and other textile materials. As a result, the inventor of the spring mattress could not benefit financially from his invention, and he kept living a life of hardship. It was not until at least 60 years later (post-1871) that his innovation was taken seriously, and the spring mattresses came into mass production with their popularity rising exponentially each following year.
Evolution of Spring Mattresses
Innerspring mattresses have kept evolving since the time of their invention, and several modifications and various types of springs have been tried. The spring mattresses used these days were manufactured in the early 1900s, and their popularity has been so pervasive that almost everyone who is more than 30 years old is likely to have used a spring mattress during their lives in the modern world. Spring mattresses contain spring coils that get compressed when a person gets on the bed. This happens as a result of the weight of the body, which applies pressure on the springs. Various models of spring mattresses use different types of coils with varying shapes, sizes, and even the number of coil springs vary from one kind of spring mattress to another. In general, the more springs there are in a mattress, the better and more reliable it is supposed to be as it is more durable and supportive. The thickness of the steel gauge is another very important factor. The heavier the gauge, the better and more reliable is the mattress. A spring mattress with a thin coil gauge is not likely to be very strong and as durable as one with heavier gauge. However, some people might want to have thin gauge coils because mattresses made out of these will be less form. Therefore, it will appeal to people who prefer softer mattresses. Recently, the coil springs made out of tempered steel have become very popular. Tempered steel is first heated, and then it is shaped into coil springs. These springs maintain and sustain their shape better in varying conditions (Hawks, 1987).
Currently, the spring mattresses are available with different types of coil springs. With such a variety of coil spring types, it becomes easier for an individual to select the right kind of mattress for himself/herself depending on his/her preferences. The most common types of mattresses are given below:
These are the coils that had been initially invented in the 1early 19th century. They were being used in the seat cushions of buggies. Therefore, one can gather from this information that the transportation sector had a direct influence on this invention. The seat cushions were bolstered by the Bonnel coils to allow them to absorb the shocks due to the jumps on bumpy roads, etc. As such, the inventor understood their importance in providing comfort to the passenger of the buggies due to their shock absorption capability and very intelligently decided to utilize them on the mattresses designed for home use. The Bonnel coils are either helix-shaped to form an hourglass type of shape. The Bonnel coils provide the most affordable option among the coil types for people purchasing spring mattresses. The drawback of the Bonnel coils, however, is that over extended periods of use, they tend to become squeaky and, as such, create unpleasant noise.
Continuous coils employ a long and continuous wire, which forms the coil spring system in the spring mattress. The wire has got a king of an S-shape, and it is made to interlink repeatedly and, therefore, becomes very durable, reliable, and ideal for long-term use. However, even the spring mattresses with continuous coils are not very expensive and can be easily afforded by anyone willing to purchase a durable and comfortable spring mattress for long-term use. Besides affordability, Continuous coils provide stability, durability, and consistent support. It is also possible to increase the coil density with their design, and this way, the support gets smoother. Smooth support provides better sleep quality. However, these coils have a potential drawback as well. As a result of their ‘continuity,’ these coils do not isolate motion and tend to transfer it along the row. That is why the rows of coils are made to run head-to-toe. The connection between two rows is helical, and it acts as a hinge and, thus, provides a high degree of flexibility across the entire mattress. This arrangement helps to enable motion isolation between sleep partners. The same arrangement leads to a lower load on each coil. Some continuous coil designs incorporate rows of continuous coils both along the length as well as the breadth of the mattress. This increases the coil density significantly and, thus, enables the bed to support more weight.
Offset coils are considered to be the best quality coil springs. These coils have the extraordinary capability of adjusting to the shape of the body as well as to its weight. As far as their way is concerned, they also look like an hourglass; however, their top and bottom are flattened in such a manner that they form a square. Each coil spring is joined with the next one, and this joining creates a hinging effect. The arrangement leads to a lot of flexibility as well as body-conformance and support capability in the coil springs. The offset coils are considered very strong and robust, and they are also very quiet. The hinge action in these coils also leads to the prevention of sagging and leaning (Hawks, 1987).
Pocketed Coils (Marshall coils)
A pocketed or Marshall coil is quite different from a typical traditional spring mattress. In this coil system, there is no interconnection or wiring of the reels with one another. The coils are therefore allowed to work quite independently from one another. Moreover, these coils are not just left to themselves as such. They are encased or wrapped in fabric pockets or sleeves. Thus, these are independently or individually pocketed. The arrangement leads to perfect motion isolation or, conversely, the prevention of motion transfer between sleep partners. When one partner gets up from bed, the other one is not disturbed at all. The coils under the person who got up regain their shape, but the coils under the partner who is still sleeping remain compressed. The motion is not rolled over, and the sleeping partner is not bothered in the middle of his/her sleep. This type of coil springs is ideal for couples who have separate sleep schedules. This coil spring system provides a superior level of support as well, and as such, is the most popular system in the spring mattresses these days. It is also used in hybrid mattresses, which combine foam and coil springs and are detailed later in this article.
Upholstery in Spring Mattresses
The coils cannot directly come in contact with the human body as they are made out of steel. On top of the reels, insulation and upholstery are a must. The coils provide the necessary support to the body. However, for comfort, which is another essential factor for any mattress, both insulation and upholstery are essential. The insulation is necessary to prevent the top soft materials from getting into the coil system. Various materials are used as insulation, and these include resin-bonded synthetic pad, sisal, synthetic fibers, rubberized curled hair, polypropylene netting, and mesh type insulators, etc. The upholstery generally consists of very common materials like cotton batting, and more recently (after the invention of foam), urethane foam is used. The purpose of the upholstery is to make the mattress very soft and comfortable, depending on the firmness level desired. It also provides the body protection against touching the spring coils, which would be quite discomforting. In general, the higher the quality of the mattress, the more upholstery, it is going to have. Many manufacturers stick to using the coil spring system in all their mattresses but simply change the upholstery to alter the firmness levels for people with different preferences. This can be easily accomplished by adding more layers of the upholstery material or subtracting them (Hawks, 1987).
The upholstery could also comprise of more expensive materials to provide a higher degree of softness. An extra layer of padding, which could be as thick as 2 inches, could give a very comfortable and soft top. Mattress covers of the spring mattresses might consist of materials like cotton and polyester and a mix of the two. Many stain-resistant finishes are also applied. The stipulation against flammability requires the mattresses to have flame resistance as well, and the cover has to provide this characteristic as well.
Foundations for Spring Mattresses
While the modern spring mattresses can be directly placed on bed frames with slats, the traditional spring mattresses required proper foundations that were necessary to hold the mattresses properly and not allow them to sag or slip. There are quite a few types of foundations available. These include a torsion bar, wooden base, and coil. The padding under cover of the mattress had to be checked before placing it on the foundation. Extra padding at the bottom ensured that the mattress would be easily placed and that it will provide more comfort to the sleeper. Some foundation manufacturers would add the padding on top of a torsion bar or coil to allow for a higher level of comfort. Low price foundations were usually without any padding. A wooden base used as a foundation consisted of a wooden frame that was covered with fabric. As this type of foundation did not have any coil element, it was easier to manufacture and was available at a lower cost. However, according to some experts, the life of the mattress would reduce if a wooden foundation was used. Their main contention was that if one purchased a high-class spring mattress with a 15-year warranty and placed it on a wooden base, the mattress would go soft within five years (Hawks, 1987).
The torsion bar does not comprise of coils but uses pieces of metal bent in a ‘Z’ shape. This is set into the frame vertically. Each bend in the wire acts as a torsion bar. Some wires have five bends, which serve as five torsion bars. The coil is another type of foundation that was employed and came in 3 forms: flat, cone-shaped, and spiked. The flat loop has got flat links or strips of steel wire that are attached to the frame horizontally with the help of helical coils. Normally bunk beds and cribs use flat coils. The cone-shaped coils are narrow at the base but wide at the top. This lets them have even compression exerted upon the entire coil. The spiked ones are wide and cylindrical at the bottom and provide a high level of support as they have got several spirals. Good quality coil foundations usually have 81 coil counts for full-sized mattress (Hawks, 1987). However, as mentioned earlier, most modern mattresses do not require a special foundation and can be directly placed on bed frames.
The Use of Foam in Mattresses
The synthesis of the first urethane foam happened even earlier than the invention of the spring mattress. The first urethane foam was synthesized in 1849 by Wurtz, and it not until 88 years later in 1937 that Otto Bayer synthesized the first Polyurethane foams by causing a polyester diol to react with a diisocyanate in Leverkusen, Germany. Both these inventions were magnanimous in their times. The invention of the Polyurethane foam started a new class of polymerization reaction called polyaddition. Interestingly, when the PU was invented, the industry considered it to be a useless invention (Szycher, 2006).
The Popularity of Polyurethane (PU) Foam
It was not until 1954 that Polyurethane foam or PU foam as it was popularly known later came to be employed in production first in Europe and then in the United States. From that time onwards, there was no looking back. In a few years, flexible PU foam became a very popular material of choice for the furniture industry, which included mattresses as well. It was also used as upholstery in car seats and other furniture pieces as well. It ended up gaining a significant share of the mattress market. As a result of its unique properties, PU foam reached out far and wide and kept capturing the mattress market. Polyurethane foam is very flexible and versatile. It is also quite lightweight and proves to be both durable and cost-efficient. Developers of polyurethane foam have since its invention come up with many different types of PU foam, thus forming many different classes that are used to satisfy the diverse preferences of the customers. No other material has this many types and classes in the mattress industry. The properties of the PU foam last for a long time and thus serve the owner for years after purchasing the mattress. As compared to many other materials, it is composed mostly of air and has several environmental benefits as well. It reduces emissions and helps to keep the room air cleaner (ISOPA, 2020) (Polyurethanesteam, 2020).
The Polyurethane foam has a significant advantage over traditional spring mattresses, which is because of the lightweight nature of the polyurethane foam. This happens due to the presence of air in the PU foam. Apart from this unique advantage, the polyurethane foam comes in different densities. The PU foam of high density is very durable as the higher the density of the foam, the better is its quality. The high density of the PU foam does not allow the allergens, dust mites, mildew, mold, etc. to enter the mattress and live and thrive in it. A typical traditional mattress will have up to one million dust mites living inside it, and they are a source of many different allergies and nuisance. People who have allergy issues have a hard time sleeping on such mattresses. The traditional spring mattresses have a lot of space in between the coil springs, which allows the dust mites to make the bed their home. The high-density PU foam does not have enough space for the allergens to live and thrive inside it. For this reason, high-density PU foam material acts as a hypoallergenic mattress and keeps the allergens away. This makes it very suitable for people who have allergy issues. They can sleep on the PU high-density foam mattress and wake up in the morning without any stuffed noses or skin irritations. The whole night is spent comfortably in the absence of such irritants.
Types of PU Foams
The Polyurethane foam used in the mattresses is the Flexible PU foam, which can take on different types and shapes. Its firmness can be varied, and it is very comfortable, lightweight, supportive as well as durable. Flexible PU foam accounts for almost one-third of the North American market for PU foams. There are other types of PU foam as well, which include Rigid PU foam, Rigid Polyurethane Foam, Thermoplastic Polyurethane (TPU), Reaction Injection Molding (RIM) PU foam, Binder PU foam, and Waterborne polyurethane dispersions (PUDs) (Christensen, 2020).
NASA and the Invention of Memory Foam
NASA spinoffs are materials that were originally invented by NASA but later came to be very useful in the industrial
and commercial sectors as well. Perhaps, the greatest of all the spinoffs from NASA is the ‘Temper Foam’, which was invented as far back as in 1966. The 60s were the decade when the race to get to the moon between the United States and the Soviet Union had been at its peak. The material had initially been developed to absorb shocks and provide protection to seats in the NASA’s air and spacecraft. However, later, it was used in many other applications, which included padding the helmets of the Dallas Cowboys in the 70s as well as the 80s. It also helped to protect patients who could not get out of bed from getting body sores and also provided comfort to the wearer of highly stylish shoes that used this material in their insoles as cushioning material. At the turn of the century, the temper foam was still going very strong in many world applications, which include amusement parks, prosthetics, automotive applications, and modern art (NASA, 2019).
Charles Yost and Temper Foam
Charles Yost was working for Systems Dynamics Group at North American Aviation, Inc. and helping them to build a recovery system that was to be deployed in the Apollo command module in 1962. In 1966, he was contracted by NASA through Stencel Aero Engineering Corporation, in Asheville, North Carolina to help improve airline seating against vibration and crashes. They also wanted him to work on developing energy-absorbing techniques to allow for a higher possibility of survival in air accidents. Yost came up with an open-cell, polymer material that was termed as memory foam, and it boasted extraordinary viscoelastic properties. It was very soft, and at the same time, it could absorb energy. Initially, this temper foam was referred to as the ‘slow spring-back; temper foam, and it could gradually return to its original shape and matched the pressure applied. NASA’s Ames Research Center incorporated this material into a new seat design for airplanes. It offered superior accident protection upon impact and also increased the comfort level of passengers on long flights. This resulted from the even distribution of both bodyweight and pressure over the contact surface area of the cushion. NASA detailed the new temper foam in one of their publications titled ‘Human Survival in Aircraft Emergencies.’ Yost formed Dynamic Systems, Inc. so that he could sell the technology of this temper foam. In 1974, the company sold the rights to this technology, but then it developed second and third-generation versions, which were more environmentally-friendly and less temperature-sensitive (NASA, 2019).
Further Developments on Temper Foam Derivatives
The company was able to expand the applications of the temper foam derivative to the medical cushion and seating for disabled people. Its SunMate viscoelastic cushioning was used for orthopedic seating pads as well as mattress pads. It also produced Pudgee, another viscoelastic foam material that could compress and also take the shape of the body sitting or lying on it. It generated much lesser friction as well as pressure on the sensitive area of the skin and was able to transfer moisture as it was wicked away from the body. The company blended both SunMate and Pudgee together to form a new material called ‘Laminar.’ The Pudgee layer helped to lower the pressure, while the SunMate layer below it provided extra support. Pudgee was very soft, while SunMate was available in varying firmness levels (NASA, 2019).
.The Development of the Memory Foam Mattress (1990s)
Fagerdella World Foams was the first company to release a Memory foam mattress in the 1990s, and it was termed as ‘TempurPedic Swedish mattress.’ After that, the use of memory foam in mattresses knew no bounds, and it also led to the development of the bed-in-a-box brands. Memory foam is a kind of PU foam, i.e., it is viscoelastic PU foam. It is also termed as Low-resistance PU foam. Many compounds, as well as additives, are added to Polyurethane to get this product, and their types depend on the characteristics desired. It is a ‘vicious’ material as it takes a long time to change its shape under pressure and also takes time to transfer energy from one point to another. It is also ‘elastic’ in the sense that it returns to its original shape once the pressure is taken away. These properties and their proportion are controlled by the differing amounts of chemical additives put into the PU foam. Most memory foams contain polyether polyol, which provides both viscosity as well as elasticity.
Benefits of Memory Foam Mattresses
The introduction of memory foam mattresses was a milestone in the evolution of the design of the mattresses. These mattresses distribute the body weight evenly and also respond to pressure to take the shape of the body. Once the weight is lifted, the foam returns to its original form. If force is applied quickly, the memory foam will still respond slowly. Therefore, it can absorb the force of impact. The mattress cushions the body adequately and cradles the body to create a cozy feeling. When pressure is removed, it returns to its original shape slowly, as well. This tends to dissipate the energy from impact. This time lag is known as ‘hysteresis.’ As its viscosity is decreased at high temperatures, it becomes flexible when it’s hot. That is why memory foam mattresses feel soft after a person lies on it for some time.
Evolution of Different Types of Memory Foam Mattresses
There are mainly three types of memory foam available in the market, and the latter two were developed to overcome the shortcomings of the first one:
Classic Memory Foam
The memory foam invented originally is the classic memory foam. It molds the body. However, it tends to retain heat. This could cause the sleep surface to get hot in the night leading to uncomfortable warmth for the sleeper. To alleviate this problem, two other types of memory foam have been created.
Open-Cell Memory Foam (Late 1990s)
Classic Memory foam is indeed pressure relieving and body-conforming, but it proved hot to sleep on. So, open-cell memory foam was developed towards the end of the 1990s. It has got the same ingredients as the classic memory foam. However, its internal structure is different. The structure comprises of pockets or open cells which enable airflow through the foam structure. This property helps to dissipate the heat. Initially, the open-cell memory foams were less dense, which did not have a right firmness level; however, now the cooling effect comes with thicker structures as well.
Gel-Memory Foam Mattresses (2006)
Another way to have an open cell structure was developed in 2006 by the very inventor of memory foam, Charles Yost to ensure airflow through the mattress. The infusion of gel into the memory foam materials by the injection of gel-based microbeads into it leads to the creation of open cells. This process creates pockets inside the structure which resembles open cells. They do not just let air through but change phase to absorb and then release heat.
Other Developments in Memory Foam Mattresses (2006 till date)
Memory foam mattresses might be incorporating any one of the foams mentioned above, or they might combine either two or all three types in the form of layers to produce a combination of the different characteristics. Many mattress manufacturers went on to add other materials like Copper or Aloe-Vera to their mattresses to get the desired effects. Copper is antimicrobial and makes the mattress both clean and sanitary. It is highly conductive and also provides quick heat dispersal, thus creating an enhanced cooling effect as well. It also wicks moisture better. The addition of Aloe-Vera makes the mattress feel very fresh at all times. The addition of bamboo charcoal also produces an enhanced cooling effect. The addition of plant-based materials to the bed instead of the petroleum products make the mattresses very eco-friendly. Latex is one such material that is used in many mattresses, and depending on how the Latex is formed, the mattress becomes eco-friendly as it comes from sustainable sources. As such, memory foam mattresses kept evolving with the addition of new useful properties with the addition of different materials.
The Uniformity in Mattress Construction over Time
Regardless of the newness of materials in the mattresses, the basic design of the mattresses remained the same in the sense that the upper part of the mattresses provides comfort while the lower part provides support. Most of the memory foam mattresses follow a standard construction type, which comprises of the following three functional layers. Each operational layer can have one or more than one coat of a certain kind of memory foam. The supportive bottom layer usually has got the high-density PU foam
The Comfort layer is the top layer under cover of the mattress. The cover of the bed is usually made out of soft and breathable fabric, which helps to increase the breathability of the mattress. The memory foam used in the comfort layer is often gel-infused, or sometimes, layers of Copper, Aloe-Vera, or bamboo charcoal-infused memory foams are used. This layer provides the required cushioning, pressure relief, body contouring, and even weight distribution. It also provides a cool and serene sleep surface that stays at the desired sleep temperature throughout the night. This layer helps to dissipate heat and wick the sweat and moisture away from the body.
This is a new development in the modern mattresses. It has been added to enable a proper and gradual transition in terms of layers from comfort to support. This functional layer is not mandatory, but many manufacturers prefer to introduce it between the comfort layer and the support layer below. It could comprise one or more layers of foam, which could include airflow foam or soft comfort foam. This layer has a higher density as compared to the comfort layer foam materials, but it is still lower as compared to the elements in the support layer below. It acts as a transitionary layer between the comfort layer and the support layer.
The support layer is at the base of the mattress. In the old days, support was provided by stone, iron or wood. This part provides the necessary pushback to the body to compensate for the downward pulling gravitational force. It keeps the body perched up on top of the mattress and prevents it from sinking into the mattress. Traditionally, this function was provided by the coil springs in the traditional spring mattresses. The type of foam used in this layer has high density, and it usually has strong edge support as well so that the sleeper will not roll over the mattress while sleeping on it.
Properties of Contemporary Memory Foam Mattresses
Contemporary Memory foam mattresses provide a variety of different benefits to the sleeper, which is a result of the following features of the memory foam material:
Memory foam adjusts to the shape of the body. When a person sits on it, the memory foam area under the body is compressed according to the contour of the body touching the mattress. Once he/she gets up, the memory foam returns to its original shape. As a result of this property, it cradles the body and gives a nice cozy feel.
The mattress embraces the individual as the body tends to sink into the mattress. It does not sink all the way because of the support provided by the memory foam and the base layer. Sometimes, the sleeper feels as if he/she is sleeping on a cloud as the plushier the memory foam layer, the more cloud-like it gets.
The memory foam mattresses provide a high degree of pressure relief to the sleeper. Many parts of the human body come under severe stress on a traditional bed. As a result of the even distribution of weight on the entire mattress surface under the body, these parts are not unduly stressed, thus relieving them of potential pressure. These parts include the hips, neck, shoulders, heels, etc. This property is highly beneficial for people who usually have arthritis or joint pains when they sleep on traditional mattresses. The use of memory foam mattresses can lead to a reduction in such issues and discomfort.
The use of memory foam mattresses enables lumbar support as well as spinal alignment. This happens as the memory foam is responsive to the shape of the body and adjusts to the shape of the natural curves. This lets the sleeper quickly figure out the most comfortable positions that keep the spine properly aligned and neutral. The sleeper does not toss and turns in the night as a result. Pain and soreness are also non-existent when the person wakes up in the morning.
The memory foam mattresses are ideal for couples. Even couples who have different sleep schedules can make good use of this type of mattress. When one sleep partner gets up from the bed, the other sleep partner is not disturbed. This happens as a mattress surface under the first partner regains its shape, and the motion is not transferred to the partner who is still sleeping. This provides a very comfortable and relaxed sleep experience for couples.
The memory foam is a high-density product. It does not have empty spaces, which can let the dust mites, mildew, mold, and other allergens to live and thrive inside it. Traditional spring beds have a lot of space in between coils, and thus dust mites are rampant. Memory foam, as well as high density PU foam, do not allow these irritants to thrive inside the mattress. As such, people who have allergies can easily make use of this mattress and not get any skin irritations or stuffed noses. They can wake up fresh in the morning and feel very energetic.
The memory foam mattress is very quiet as compared to a spring mattress. This is very important for many couples who sleep on the bed, and they do not want the noise or squeaky sounds to wake up the other sleep partner. While there will be no motion transfer, the presence of noise can still cause the other sleep partner to wake up when the other gets on the bed or off it. With memory foam mattresses, there are no squeaky sounds and thus no noise-related disturbance.
Development of Certification System for Foam Mattresses
With time and in relation to the regulations regarding flammability standards and the need to minimize the use of chemicals in the production of mattresses, many different certification systems have been developed by various third-party international agencies. The quality of a memory foam mattress can be assessed by the certifications the memory foam and PU foam used it carry. The certifications are issued after conducting tests on the mattresses rigorously before certifying them. The most widely used and accepted international accreditation is the CertiPUR-US certification, which assures the purchaser about the content, performance, and durability of the mattress. In 2008, many high-quality US foam producers were worried about the penetration of sub-standard foam materials in the market. Many contained chemicals that had been banned in the United States. The CertiPUR-US program was developed in answer to these concerns. This certification also ensures that the mattress does not contain any harmful chemicals like TDCP, phthalates, formaldehyde, mercury, lead, other heavy metals, flame retardants, and other toxic substances. It also assures the purchaser that the Volatile Organic Compounds (VOCs) emitted by the mattress are within acceptable limits (CLC Team, 2019). There are other certifications as well. One of the popular ones is the Oeko-Tex standard 100, which tests the mattress against the presence of 100 harmful chemicals. This standard predates the CertiPUR-US certification. It was developed in 1992 (Oeko-Tex, 2020).
Remedying the Shortcomings of Memory Foam Mattresses
There is nothing perfect in this world. Everything has a downside to it. Memory foam is no exception. As such, these mattresses have been continuously going through innovations and developments. Some sleepers often feel that they feel ‘stuck’ on the memory foam mattress as it cradles their bodies and causes a sink to occur. This feeling could worsen with time as the bed gets older. There is. However, a solution for this problem and many manufactures have developed quickly responding memory foam surfaces that do not regain shape gradually but are very quick to respond, The smart response foams allow the sleeper to get rid of the ‘stuck’ feel, and it gives the ability to the sleeper to roll over the mattress which is a bit hard to do on a traditional memory foam mattress. Many manufacturers have developed patented technologies to provide quick responsiveness to the top part of the bed to allow a very comfortable sleep experience. However, it is not necessary to use proprietary technologies as the same quick response property is available with the natural Latex product, which is now extensively being used in mattresses. The entire upper layer of the bed could be made out of Latex, or at least the top layer is made out of it to enable the quick response. The other shortcoming regarding memory foam is the trapping of heat; however, for remedying this problem, many different infusions into memory foam ensure that the mattress surface will stay at the desired sleep temperature throughout the night.
Development of Latex Mattresses (1920-1940s) till date
Latex Mattress has been around since 1930s when Dunlop, with the help of scientist E.A. Murphy developed the first latex mattress. The development process had continued to span from 1920s to the 1940s in all Natural Latex is a sustainable product, and its inclusion in the mattress makes it eco-friendly. Latex Mattresses were developed as their comfort level, and body-conformance turned out better than that of memory foam. The Latex is also quickly responsive, and it does not let the sleeper feel ‘stuck’ on the mattress surface. They are also very durable. The most significant advantage of Latex is that natural Latex does not contain any harmful chemicals, and some of the latex types are even biodegradable. Thus, it is a very eco-friendly material and provides comfort as well. It is also very durable. Natural Latex is extracted from rubber trees, and because if it is natural, there is minimal off-gassing. Synthetic Latex is made out of many different materials, and mostly by using Styrene-Butadiene Rubber (SBR); however, mattresses made out of synthetic Latex are not as durable as the natural latex mattresses. As far as natural Latex is concerned, it is manufactured through the Talalay process or the Dunlop Process (Deliege et al., 1998).
The Dunlop method pours the rubber tree sap into a mold, and when it solidifies, the upper part has a lower density as compared to the upper part.
Talalay Process (1950s)
This process was developed to remedy the non-uniform density of the latex obtained with the Dunlop process. It was developed in the 1950s. However, the patent which was obtained in England is with Talalay Global, which was formed 35 years ago in the United States (TalalayGlobal, 2020). During the Talalay process, a vacuum is used while the mold is being filled. This fills air into it and creates a uniform density latex material.
According to a study, the latex mattresses reduce the peak body pressure on the buttocks and the torso and also provide a higher proportion of low-pressure areas as compared to the PU foam mattresses. Thus, they enable a more even distribution of the pressure as compared to the PU foam mattresses. This is true for all three sleep positions, i.e., back, front, and side. This information is even more significant when one considers the long-term use of mattresses, which would reduce the possibility of getting sores (Low et al., 2017).
Development of Hybrid Mattresses (2008)
In the last 90 years or so, the most popular mattresses have been the spring mattresses and the memory foam mattresses. The spring mattresses are known the world over for their ultimate support, while the memory foam mattresses (or Latex) provide ultimate comfort. This has made possible the development of Hybrid mattresses, which combine the best of the worlds of sympathy and support. These mattresses contain memory foam or gel-infused memory foam or even Latex in the comfort layers, as well as the transitional segments. Still, the support layer is made out of pocketed coil springs. This provides an excellent and almost ideal amalgamation of the best features of both the memory foam (or Latex) and the pocketed coil springs. Most high-quality mattresses available from the most advanced mattress manufacturers are hybrid mattresses, and these provide comfort, support, and durability all in one package.
Various Foam Combinations in Hybrid Mattresses (2008 till date)
While the bottom layer, which provides support, is almost always made out of pocketed coil springs, the comfort and transitionary layers might employ as any type of foam material. These include memory foam, gel-infused memory foam, Aloe-Vera, bamboo-charcoal, green tea, Copper, etc. are very popular infusions. Very often, manufacturers use patented foam technologies as well to increase ventilation through the mattress or to make the surface of the mattress more responsive. The manufacturer also uses Latex in the comfort layer, thus making the mattress highly responsive, pressure-relieving, thermoregulating, body-conforming, motion isolating, comfortable, and highly supportive at the same time. As such, hybrid mattresses are intended to provide all the best features possible.
The Growing Trend towards Organic Mattresses
Human health and wellbeing are prime concerns for consumers in the modern world. The modern consumer is also very concerned about the eco-friendliness of the supply chain of the products they purchase. While the primary concern in the past related to human health has always been directed towards finding solutions that protect against bacteria and allergens, the extensive use of chemicals in the last century has led the consumers to wage war against the use of harmful chemicals in the products they purchase. Proposition 65 for California residents is a case in point. This proposition bans the use of any product that might contain carcinogenic materials that lead to the possibility of causing cancer in individuals who use the product. Natural Latex along with pocketed coil spring layer at the bottom is preferred by many such eco-conscious consumers. It brings them eco-friendliness as well as numerous health and wellbeing benefits, which include a higher level of comfort, minimal VOC emissions, cleaner room air, and long-term comfort. However, Latex is not the only material that is being used in organic mattresses. High-quality wool and cotton batting, which are sourced in an eco-friendly way is also great sources as comfort materials.
There are quite a few international agencies that award certification for natural and organic mattresses, and these include Global Organic Textile Standard (GOTS), Global Organic Latex Standards (GOLS), Greenguard and Greenguard Gold, USDA Certified Organic, etc. These standards evaluate the products after examining their supply-chain as well as their manufacturing, packaging, and distribution channels
Smart Mattresses and the Role of Technology
Smart Mattresses are set to dominate the mattress spectrum in the future. The efficacy of smartwatches and fitness data is already well-known. With the advent of technology into mattresses, the data on health and sleep is collected where it is the most appropriate to obtain it, i.e., on the mattress. Thus, fusing the sleep-tracker technology with the mattress has a lot of benefits as not only the sleep patterns are monitored, but the mattress can also be regulated. The information collected can contribute to future developments in mattresses and bedding as well. It might be possible in the future to eliminate the ‘disturbances’ that wake-up people in the night in light of such information. Smart mattresses also provide adjustable firmness levels for each bedside. A mattress can be made smart enough to tilt the sleeper’s head when he/she snores. Thus, the possibilities are endless. The concept behind smart mattresses had already been tested in hospitals as Electronic Profiling Beds (Neuberger, 2011), however, now the concept has widened in its scope.
These mattresses monitor the heart and breathing rates as well and provide a higher level of detail as compared to the wearable health trackers. Many new smart mattresses are now available with climate control features. Some can create flows of cool air on demand. Many of these smart mattresses create two separate zones on the same mattress to accommodate the preferences of the sleep partners with regards to sleep temperature. Smart mattresses can be incorporated into smart homes of today. Alexa can be made to connect to a smart mattress, and once the sleeper wakes up in the morning, he/she can inquire about the sleep quality experienced
The Future of Mattresses
Machine makers are encouraging the mattress maskers to incorporate more and more technology in their products and exhibit these products in industry fairs every year. A lot of these high-tech machines that speed up mattress production and packing on the assembly lines with minimal human involvement, thus reducing the possibility of errors. Many of these machines are meant for making spring mattresses in a very efficient way. Others cut different types of foams efficiently and then glue them together without any human involvement. Thus, human handling during manufacture will be eliminated in the future (Nelles, 2016).
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