3 ABOUT FOAMS (Series Cushioning 3 of 9)

Post 744by Gautam Shah


3.12 Styro-Foam Bean bags at Google Developer Day 2007 httpswww.flickr.comphotoskentbrew53995451753

3.3 Polimide Aerogel Film GRC-2011-C-03587 - PICRYL Public Domain

Foams are air-entrained objects, where nominally a gas is trapped in solids or liquids. Foams, are called ‘examples of dispersed media’. The gas, the main dispersing agent is divided into bubbles of different sizes, called ‘polydisperse’. Foams are usually disordered with many different sizes of bubbles. In liquid-foams the bubbles continuously resize through collapse or assimilation. When the dispersed medium is very thin, it is called a type of colloid. Though some claim, ‘A Foam is a colloidal solution of liquid and gas, with liquid acting as dispersing medium, and the gas acting as the dispersed phase. So it cannot definitely be said that it is a solid, liquid, or gas. It is a colloidal solution’.

3.8 Aluminium Foam Wikipedia Image by Stehfun

Foams are nominally, air entrained compounds, but, the air (or a vacuum) pockets could be continuous- interconnected, or could be isolated. In the first case, the structure is fairly stiff (non-compressible), so, called solid foams (just a ‘light-weight hollowed mass’). In the second case, for the soft foams, the structure is not stiff, it can collapse, and which may or may not recover to the original shape.

3.2 Aerogel Flickr Image 5810742717

Aerogel is a synthetic ultra-light ‘porous’ material (98.2% air) that is derived, when a liquid is replaced by air. The result is a solid with extremely low density and low thermal conductivity. Aerogel is a synthetic porous ultra-light material derived from a gel, in which the liquid component of the gel has been replaced with a gas without significant collapse of the gel structure. It results into a solid form of extremely low density. Such materials show extremely low thermal conductivity. These have been called (mainly due to the translucent mass) frozen smoke, solid smoke, solid air, solid cloud, and blue smoke. Silica Aerogel feels like fragile expanded polystyrene to the touch, while some polymer-based Aerogels feel like rigid foams.

3.5 Sea foam on ocean beach http pixabay.com 3903736

Froth: The fizz on beer or the soap suds (bubbles) in bath water, are foams, a mixture of gas and liquid. Whisking the milk and egg-whites produces foam, air bubbles as an emulsion. Blowing a gas through a molten plastic fills it with bubbles, and when the plastic cools and solidifies, the gas bubbles are trapped inside, making a foamed-plastic, used for filling cushions, and packing of goods.

3.9 Beer Froth httpswww.piqsels.comenpublic-domain-photo-flyva

Materials have three states or phases of matter, namely Gas, Liquid, and Solid. These states also denote the structural rigidity and resistance to change of shape or volume. The states or phases are due to the temperature and pressure.

3.1 Forms of Compounded Materials

One of the earliest realizations of a foamed structure was the pumice stone (very porous, froth like volcanic glass, cooled fast without the crystallization). It is used as an abrasive for cleaning (rubbing the body-hair and fabrics), polishing, and as scouring compound. Another was the dried froth, spongy material (locally, W. India, called Ush) that gets deposited against the slightly alkaline shores of rivers and rivulets. It was used for washing the clothes. Ceramic materials, such as bricks are produced by addition of organic fibers (typically rice husks, chopped hay or mustard leaves and stalks) into the mud. On firing the organic material burns out leaving a lighter and hollowed mass.

3.23 Porous Brick of Clay httpswww.vhv.rsviewpichobhiJo_buy-red-clay-bricks

3.15 Dunlop Lateax Foam

Right from early days, the rubber-based foams had issues of density, heat dissipation from the mass, deterioration of the material due to defective vulcanization and release of VOCs. Some of the issues were partly solved by providing hollow cores on the back-face, which achieved additional compressibility (even with high density structure) and better aeration. The foams were excellent materials for thermal insulation, floating devices, packing, padding and stuffing of toys.

3.17 & 3.18 Open and Closed end foam structures

Foamed or Cellular materials are called expanded plastics or foams. These are made in various types, from soft and flexible to hard and rigid. There are three types of cellular plastics.
• Blown, an expanded matrix such as in a natural sponge.
Syntactic, encapsulation of hollow organic or inorganic micro-spheres (or nodules) in a matrix.
Structural are composed or formed materials with dense outer skin surrounding a foam core.

3.27 Methods of forming Cellulor Structures

✓ Gas in Liquids or Liquid foams These are like, froth, aerated soda, washing soap suds. These become little more stable or last longer, when a stabilizer or surfactant is present or added. In foods Proteins (eggs, oils, gums) act as foaming agents. Nearly all fermented foods are like foams. In aerated drinks and fire extinguishing foams, Carbon dioxide is dissolved. Foaming makes many foods lighter. Gas-liquid foams have high surface area and is exploited for flotation and foam fractionation. Many foaming conditions are not always desired, such as lubricating oils, chemical processes. To break the foams air releasing agents or skimmers (blades moving over the surface).

3.28 Gas in Liquid foam httpswww.pxfuel.comenfree-photo-jticg

✓ Gas in Solids or Solid foams. These are like breads, cakes, rubbers, polystyrene (Thermocole), polyurethane, paper pulp, slag, ceramic foam, sponge iron and tantalum or titanium sponge (for prosthetics). Solid foams are mostly used as lightweight cellular engineering materials.

3.6 Puffy mass of Idali (South Indian fermented food) httpswww.flickr.comphotosjuliepics 4273563605

✓ Solid foams are of two classes, based on their pore structures. Foams with open-cell structures, called reticulated foams, where the gas pockets are connect to each other. Foams with closed-cell structures, called cellular solids, where the gas is trapped into discrete pockets, each completely surrounded by the solid material. A bathing sponge is an open-cell foam, the water can be sucked in as well as squeezed out. A shoe base or sole is a closed-cell foam, though ‘porous’, cannot soak water as the gas pockets are sealed and separated from each other.

3.7 Bread foamed cavities httpspixabay.comdephotossauerteig-brot-brot-sauerteig-5001833

There are other classes of closed-cell foams, known as syntactic foams. These have embedded hollow particles or nodules placed in a matrix material. The nodules are made of glass, ceramic, polymers, etc. Such syntactic foams offer very high strength-to-weight ratio and so are useful for deep-sea and space applications. Memory Foams also use a syntactic shape-memory polymer, as a matrix.

3.16 Open cell polyurethane foam httpswww.flickr.comphotoscore-materials3841032416

✓ Foams can be forms of Composites. It is a product that is made by mixing fibers like straw, hair, coir, hemp, jute, papyruses, rice-husk etc. into fillers, like latex, mud, gum, etc. The filler fibres are arranged into patterns such as, random, unidirectional (aligned in a single direction), multi-directional (oriented in two or three directions) or spaced continuous strands. There is no compaction of the mass. On curing or hardening the mass has cavities that gives an identity of air-filled material. The materials are not very compressible, but have resilience. Such composites can absorb shocks, vibrations, sound and in few instances water or moisture. Rubberized-Coir fibre sheets are used with polyurethane foams and other foams for mattress making.

3.14 Aluminium foam sandwich

✓ Aluminium foam sandwich (AFS) is a product made of two metallic dense face sheets and a metal foam core made of an aluminium alloy. It is produced, once the raw MMC (Metal Matrix Composite) is melted, then transferred to the foaming apparatus, where gas is injected into the melt and dispersed using either rotating impellers or vibrating nozzles. Such panels are used as insulation face in very hot environments, as sound damping layer, reduced weight, increased energy absorption in case of crashes, and in military operations to combat the concussive force of IEDs.

3.13 Stabilized Aluminium Foam Wikipedia Image by CymatTechnologies

3.30 PU Leather

✓ Integral skin foams, also known as self-skin foams, have a high-density skin and a low-density core of the same material. Examples of integrated skin foams include, furnishing fabrics like rexines, insulated rails and handles, arm rests, baby seats, shoe soles, and mattresses. Exterior sandwich or composite panels (Aluminium composite panels -ACP), are used for external and internal architectural cladding, partitions, false ceilings, signage, machine coverings, container construction, etc. Materials like ACP may not be a sandwich construction, but through application like a coating on one face (that foams and insulates). ACPs often have highly combustible Polyethylene (PE) core, which was the principal cause of the rapid spread of flame in the 2017 Grenfell Tower fire in London. Similarly the coating on the the aluminium sheets with polyvinylidene fluoride (PVDF), fluoropolymer resins (FEVE), or polyester paint may contribute to combustibility and spread. In packaging, fluted polypropylene boards and polypropylene honeycomb boards are used for impact resistence. Ship cabins use lightweight door shutters, table tops, cupboards and shutters formed of wood veneers with core of foam.

3.29 ACP Panel tiles for Spaceship Earth at night Image by Benjamin D. Esham Wikimedia Commons

Under appropriate conditions almost any Polymer resin, thermoplastic or thermosetting can be foamed. Plastics, commonly foamed include vinyl, polystyrene, polyethylene, phenolic, silicone, cellulose acetate, and urethane, polystyrene or polypropylene. Hydroxyl terminated polyethers are often used to prepare flexible foams, typically for furniture cushioning. Hydroxyl-terminated polyesters, are popular for making rigid foams such as those used in custom packaging of appliances.

3.19 Porous ceramic filler for biological filtration in aquarium filter httpswww.flickr.comphotos30478819@N085103809288651038092886

Unlike many polymer foams, metal foams remain deformed after impact and can therefore only be deformed once. Reticulated foam, compressible and porous material. For orthopedic applications, tantalum or titanium foams are used for their tensile strength, corrosion resistance and bio-compatibility.

3.24 Sand holes structure background a hole httpspixabay.comdephotoszellen-sand-lcher-struktur-4871686

✓ Many natural substances such as rocks and soil (e.g. aquifers, petroleum reservoirs), zeolites, biological tissues (e.g. bones, wood, cork), and man made materials such as cements and ceramics can be considered as porous media and not as Foams.

3.26 Spray Foam Applicator for Open Cell Foam WSikipedia Image by Chicagosprayfoam

Foams are used as shock absorbers and vibration retarders. There are many other shape configurations that absorb the impact. Air-filled constructions or compositions, such as the air-filled tubes and bubbles, tubes and tyres, fibers like carded cotton, rayon, coconut, wool, hay, straw and bird-feathers are pressed into mats or sheets. Mineral wool is a fibrous mass formed by spinning or drawing the molten mineral or rock materials such as slag, glass and ceramics. These have resilience as well compressibility. Multi layered corrugated papers, paper pulp formed items (egg crates), layered beds of hair (brushes), coiled springs, pre-stressed and shaped shock absorbers of spring steels, etc.

3.31 Paper Pulp Paper mache packaging


HAMMOCKS (Series Cushioning 2 of 9)

Post 743 -by Gautam Shah

2.1 Gustave Courbet Lady in the Hammock 1844

A variant of the hay-spreads or stuffed bags for sleeping were the hung hammocks. The Hammocks are simple long pieces of cloth or nets (like for fishing). A Hammock is a sling, made of fabric, entwined net of twines or woven mats. It is suspended between two or more points on tree trunk, column, wall or ceiling. Hung hammocks forms a very narrow sling, to widen it, both the ends have spacer-sticks.

2.3 Joseph in a hammock on wheels A rudimentary type of coach, depicted in the Anglo-Saxon manuscript Old English Hexateuch (11th century) Wikipedia Image by Ælfric of Eynsham (editor)

Hammocks do not need a mattress and one can even do away the pillow. Pillows or head supports are required for head related activities like reading or drinking.

2.2 An ISAF soldier rests during Op Medusa Wikipedia Image by Afghanistan Matters from Brunssum, Netherlands

Like all other sleeping devices, mattresses, beds, manch (platform) need a flat resting ground (floor), but hammocks are flying or hanging devices, which just need side connections for hanging. Hammocks can be hung over wet or muddy floors, stock rooms, guns, armaments, stocks in warehouses, between birth in carriages like horse, automobile, railways and space crafts. Hammocks are used for fun, casual swinging, relaxation, siesta, reading, contemplation and slumber.

2.6 An Able Seaman asleep in his hammock on board HMS ANSON. Wikipedia Image

2.7 Traditional Mayan home in Santa Elena, Yucatan, Mexico Wikipedia Image

Hammocks are used in many parts of the world, in varied environments, conditions and for different purposes. Hammocks were developed by native inhabitants of the Americas for sleeping. These were adopted by explorers traveling in wooded regions. Hammocks are collapsible to a small volume and lightweight for transportation. Hammocks have thin body mass, which even, if gets wet, dry out quickly. A hammock covered with net eliminates the chances of mosquito bites. Hammocks do not need mattresses, so there is no fear of dust mites or lice and other contagious skin infections. It also provides safety from insect stings or animals bites like snakes, mosquitoes, ants, bees, etc.

2.8 Hammock floating over tools and equipments and ofcourse animals and insects Travel and adventure in the forests of Venezuela http www.flickr.com photos internetarchivebookimages 14595904369

A hammock experiences three types of movements, 1, the swinging motion, 2, micro changes due to the breathing, 3, twitching, due to the shifting of the body posture. Hammocks were adopted by sailors, as its capacity to swing counters the sickening motions of the sea waves. Later, these were used on marine vessels. Ordinarily the rocking motion of a hammock is unnerving, but once accustomed, it encourages deeper sleep.

2.9 Wayuu open-air Bedroom with hammocks Wikipedia Image by Leonfd1992

Swinging motion speeds up the change from wakefulness to the deep sleep (stage-2 sleep). Sleeping in a hammock relieves the pressure on body muscles, as it allows minor adjustments of tissues and body-fluids. There is equal distribution of pressure on all parts of the body, as the surface of the hammock is stretchable and flexible.

2.10 Hammock without the spacer stick becomes too narrow for turning around https www.pxfuel.com en free-photo-jeunm

2.11 Hanging Hammock of net httpswww.publicdomainpictures.netpictures310000velkahanging-hammock-15742890792mK

Royal navy in 1597, for the first time mentions the hammocks as ‘hanging cabbons or beddes’. Hammocks were preferred over fixed bunks, as could be hung between-over the guns, rope coils or wet floors. Hammocks require no mattresses, and so were ideal against proliferation of skin deceases among sailors (due to vitamin C deficiencies). During the colonization of the 17th C, the hammocks became a world-wide a marine facility. Hammocks have also been employed on spacecrafts in order to utilize available space.

2.12 The Royal Naval Volunteer Reserve during the First World War Q53295 - PICRYL Public Domain Image

2.13 U S S Brooklyn, hammocks on deck - PICRYL Public Domain

Hammocks allowed comfort and maximum utilization of the cramped space in temporary army tents. Hammocks are used as a lightweight bed for tropical climate explorers. The advantages of the snug Sleeping bags for colder climate campers and mountaineers are of different class. Hammocks have a sleeping facility that is of a thin body fabric or net structure and off the ground. This creates an air movement system around the body, same as the Indian Charpai.

2.5 Hammock without the spacer stick becomes too narrow for turning around httpswww.pxfuel.comenfree-photo-jeunm

2.4 Bamboo or can matt weave Hammock With space sticks at the ends httpswww.pxfuel.comenfree-photo-oblis

Early hammocks of Latin Americas and other pacific islands were of local materials like woven tree bark fibers and sisal fibers. These were soon replaced with cotton and other fibers, spun into ropes. The salvage (ends) of the fabric needed extra reinforcement. For these the warp-yarns at the edges, are made heavier and stronger, alternatively annealed copper or steel wires are used. The edges are also stitched as doubled seams. Net weaves or basket like constructions, also need edge reinforcement besides extra strength in sections where the buttocks of the body exert high stress. Another issue is keeping the hammock wide-open, for sleeping side ways. These is achieved with use of spacer bars, pipes or sticks at both the ends.

2.15 Baby in the sack

2.17 A young child in a makeshift wHammock. photo taken by flickr user bingregory

Children Palana or Zhula (India) cradles or Ghodiya (Gujarat India) provide the movement experience similar to a hammock. There are two major configurations, Flat beds offer only the swinging motion, but hammock style curved ones, bend the body in the manner of a mother’s womb. Best or popular movements are sideways but some contraception permit movement in head to feet direction. A bassinet, bassinette or perambulators, are baby carriages, with some additional facilities like head-shade, shock absorber springs and wheels. The springs are soft (spaced spirals of compressible springs) that generate extra vibrations to compensate, for the hammock like movement.


In India, Sarees, Dhotis and bed sheets are used to function as a hanging hammock. Injured patients, dead bodies and colonial officers, in hilly travel were carried, through hammocks hung from a long horizontal mast (a sleeping palanquin). Patients and dead bodies are carried in hammocks (called soft stretchers) through small stairs or elevators (which do not allow full length stretcher or coffin). The shroud is used as a hammock to lower the body in the grave. Hammocks have also been employed on spacecraft in order to utilize available space.

2.16 COMA, a film 1978 Directed by Michael Crichton, Novel by Robin Cook, and main Cast of Geneviève Bujold + Michael Douglas), ‘shows brain dead patients in hanging, swinging and continually variable positions

COMA, a film (COMA 1978 Directed by Michael Crichton, Novel by Robin Cook, and main Cast of Geneviève Bujold + Michael Douglas), ‘shows brain dead patients in hanging, swinging and continually variable positions for trading of live organs and body fluids’.

2.18 Guatemala-hammocks-market-colours httpswww.pxfuel.comenfree-photo-ozjxf

Two-way woven fabrics, through knitting mode eliminates the strength differential (and stretching capacity) in weft-web directions. Hammock pose many risks. This may include, neck and back pain, limited space shape for stretching, fixed or limited posturing, risk of falling out and difficulties of getting in or out.

2.19 Natives carrying European in covered hammock]- PICRYL Public Domain Image

AIR-ENTRAINED MATERIALS (Series Cushioning 1 of 9)

Post 742 -by Gautam Shah


1-14 The Sleeping Gypsy ART by Henri Rousseau httpswww.flickr.comphotosralphandjenny 4440860047 4440860047 c15fb32619_c

Air-entrained materials as shape-able materials and pre-shaped objects are in use since prehistoric times. These continue to be used for supporting the body or limbs in various positions such sleeping, reclining or sitting. These materials and shapes allow better flow of body fluids, heat conservation, dissipation and absorption of the reverse impacts and vibrations.

1-1 ancient-mattress-5784025c5f9b5831b5f7746e

In ancient times, bedding materials were of vegetative origins like grasses and leaves. The materials retained the body moisture causing putrefaction, so required frequent replacement. Another reason for frequent replacement was that all ‘beds’ get infested with lice. It was difficult to terminate the lice-infections, so bedding stuffs were occasionally burnt.

1-2 Iroquoian_Village,_Ontario,_Canada40

1-20 Typical Hay Barn httpswww.flickr.comphotoscalliope8382839831

Unknown visitors and guests brought in infections and smells. The problem was acute at Inns, Sarais and Brothels. In dwellings, such visitors were asked to sleep in hay lofts. The hay stocks were seasonally replaced, the hay floor was ‘re-done’ or the bedding hay was frequently smoked or sun-dried. The vegetative materials were mixed with rice husks (fairly stable material) and eucalyptus or other aromatic leaves, to act as the natural insecticide. The ‘floored sleeping arrangements were prone to rodents, insects or snakes. The lower sections close to the floor, were affected by cold draughts in winters.

1-4 Interior of an inn or Sarai Long White Mountain Raised platforms for sleeping No mattresses or special floor covering

1-19 Farmer a sleep on hay

1-3 image

Winters in Northern Europe are too severe for spending nights in hay lofts. Guests shared with the family and servants, the warmth of kitchen-fire side platforms. These platforms were multipurpose facilities, used for food preparation, dining and social interactions. Privacy was not a medieval consideration. Loose straws of hay in kitchen area were fire-hazard, and so not preferred. Instead chopped grass, hay, straw, chaff, or bird feathers were stuffed into sacks or burlap bags. Such bags, the manageable stock served as the raw mattress for centuries. Where woven fabrics were difficult to get, the chopped fillers were contained in bottomless, four-sided frames, or open boxes. The chopped hay in heaps, bags or boxes were sometimes topped with leather, pieces of tapestry, wool or heavy quilted fabrics.

1-18 Stuffing Materials of Farm origins

Straw vs Hay
Hay vs Straw Hay is harvested while a live, healthy plant. Straw is the dead stalks of plants after the valuable upper parts of the plants have been harvested. Hay is valuable as provides better nutrition to animals while straw provides little nutrition and so often burnt. Straw has sharp edge and can hurt anyone handling or eating it. Other farm or agriculture products have some value include chaff, husk etc. There value was as stuffing material in mattresses. due to finer size and non rotting nature. Chopped Straw is used as an additive for mud walls, whereas chaff and husk are added to brick muds. These were also used as floor spread for stables, poultry farms.

1-16 Manch or raised Platform Child, sitting, occassionaly used for sleeping Ethiopia, Tribe, Africa, Culture, Omo, tribal httpswww.pxfuel.

Questions have been raised, which came first the Mattress or Pillow? No find of historical, archeological or narratorial evidence supports the ‘mattress’ as the inevitable form of sleeping. Japan, China, India and many other countries of the region have used ‘head-supportas the required tool for sleeping. Even today, travelers, fakirs, beggars, and road side squatters, may not use a mattress, but use the elbow for supporting the head. The head supports were through the raised head-bar of Charpais (India), wood pieces carved to shape of head, own entwined hair, Pagari (Indian head gear as head-tied or loosened form), bundled piece of tapestry or travel bag and stuffed pillows.

1-11 Ancient Head rests

1-12 Makura_(The Wooden Pillow Two sleeping women Japan 10796813065

1-15 Wooden sticks as sleeping floor Iroquoian Village Ontario Canada

Long houses of primitive age had two types of sleeping facilities, parallel and perpendicular to the central aisle or fires. For sleeping solidly built or leg supported platforms were created, often supplemented with ‘bunks’ at upper level. The legged platforms had strips of wood or woven mats with piece of raised wood as the head support. Many regions in South Asia have been using Manch or Manchi (a wood platform covered with woven mat), often taller than the height of the crop.

1-6 Madyaranga_Ranganatha_temple

1-17 Indian Sadhu Resting

Buckwheat pillows were once very popular and still admired by many, except for the crushing sounds during head shifting. Main stuffing material were of buckwheat hull shells. These are durable and fairly long lasting. The pillows originally came from Japan. Buckwheat controls the temperature.

1-13 Man taking a nap over rough and inclined terrain with a bush heap as head support in San Cristobal Cusco Peru Wikimedia Image

Pillow shells or bags are made of woven fabrics, leather, mats, etc. The shells or bags are stuffed, and so naturally contour to the shape of the head. Feather bags or pillows sag fast, making the mass stiff. In case of a puncture the feathers spread out, and it is difficult to restuff. Other stuffing materials include, cotton, wool, coconut. Kapok (silk-cotton -Ceiba Pendandra) fibers.

1-7 woman-sleeping-out-vietnam-fruit-seller

The stuffed mattresses or pillows (and perhaps some form of bolsters) had some common problems such as uneven sagging, loss firmness, hygiene, unmanageable high volume and consequent heavy weight.

1-5 Adam Sleeping

A k’ang is a platform bed with a stove built underneath. It was used for different purposes through the day. Starting around 300 AD, pipes or flutes were introduced to distribute the heat and ventilate the smoke from stove. Spread of palm fronds or mat was sufficient as the bedding surface.

1-8 Sleeping Buddha in Pandavieni cave

1-9 buddha-gold-sleeping

1-10 hatyai-4109019_960_720