CORROSION PROOFING TREATMENTS

Post 367 –  by Gautam Shah 

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Corrosion is degradation of a material due to an electrochemical oxidation process with the environment. The process is more common with metals, but can also cause disintegration of a polymer due to sunlight exposure, or in case of ceramics and stones as seen as efflorescence.

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Stable metals like copper and precious metals like Gold, Silver, Platinum, are less prone to disintegration. Some metals form their own protective cover on the surfaces to prevent, or slow down the corrosion.

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There are several ways to stop or retard the corrosion. One, is to isolate the metal object from environment and other metal objects, and Two, is to constitutionally alter the metal to reduce its vulnerability to rusting. In both the cases the availability of electrons for displacement is reduced. Metals are protected by formation of a barrier. The barrier could be an applique coating like paint or an integrated one like plating or galvanizing. Integrated barriers are also formed by metalizing, surface alloying and ceramic formation. The barrier could be generated by the material itself such as the Patina on bronze. The Barrier could remain on the surface forever, or covered by other coating systems.

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Barrier protection: One of the oldest methods of protecting the metal surface is plating with a metal of stable nature such as Tin, Silver or Gold. Such plating processes were expensive and used for small objects. Post middle ages, metal household objects of iron were covered with a layer of coloured ceramic-glass called enamel. Enamel is inert, and adheres tightly to the steel, protecting it from corrosion while providing attractive appearance. Later chromium plating via electrolytic compounds began to be used as a protective-barrier coating on steel. To get better adherence, the steel is first electroplated with layers of copper or nickel. Today many other types of barrier protections of organic nature such as paints and polymers are used.

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The oxide layer that forms on metals when they are exposed to air also constitutes a protective barrier. Bronze, Stainless steel and aluminum form the most stable and protective of such films. The thickness of the oxide film on aluminum is often increased by making the part function as the anode in an electrolytic cell. This process, called anodizing, enhances the corrosion resistance and makes it easier to colour the surface. The films that form on copper and steel as a result of corrosion (commonly known as tarnish and rust) are somewhat thicker and show a characteristic colour that is often incorporated into the design of the part.

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Galvanic protection: Applique protective films (like paint) on steel are susceptible to being broken at scratches and sharp dents. This occurs in automobiles and other entities, as the applique films have no ability for self-healing. A protection application of zinc metal which has greater capacity to donate electrons then the steel, if forms a prime (first layer on steel) surface, then the objects can be protected from effects of corrosion. This is called galvanic protection. A layer of zinc can be placed on a steel surface by either by hot-dipping or electroplating. Galvanized steel is much more resistant to corrosion than un-galvanized steel. Where a galvanized coating is cut or scratched, the zinc flows in over the exposed area and provides continuous protection. Cadmium can also be deposited for galvanic protection of steel. Hot-dip aluminum-coated steel is used in the exhaust systems of automobiles. At low temperatures its action is galvanic, but at high temperatures the oxidation forms a barrier layer. Galvanic protection is also provided by imposing an electrical potential on steel structures.

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Other coating techniques

Among other methods for applying a metal layer to metal is thermal spray coating, a generic term for processes in which a metal wire is melted by a plasma arc or a flame, atomized, and sprayed onto a surface in an inert gas. A process similar to this is vacuum coating wherein metal is evaporated and deposited as coating in high vacuum. High-temperature bearing super alloy components, such turbines are given oxidation protection by annealing them in a chamber containing volatile aluminum chloride.

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Metal coatings are surface treatments that form the first coatings in a multi coat set. Conversion coatings are of basic two types: phosphating and chromating. These are  temporary, but provide an adequate substrate for subsequent applications.

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Phosphate coatings are used for ferrous, zinc metals, aluminium, tin and cadmium metal surfaces. It is a thin, porous, insulating and adherent application that allows keying of the applied paint film. The electrical inertness of the coating arrests corrosion spread to local spots. Phosphate coatings are applied by immersion, brush application or spraying. Zinc phosphate coatings are smooth and fine-grained treatments, used for reducing the corrosion creep under the paint. Coatings containing manganese phosphate are less widely used as paint pre-treatment because they have a large coarse crystal structure although these heavy coatings are very useful as oil-carriers and have good wear resistance, which is advantageous for engineering components.

Steel structure showing residues of inner coatings

Chromating is formation of a chromium oxide film on the metal surface. It is used to increase corrosion resistance of metals like aluminium, magnesium, tin, zinc and cadmium. It is also used to enhance the tarnish resistance of copper and silver.

Diffusion Coatings are also known as cementation coatings as part of the applied material interacts and forms alloys with the substrate. Cementation coating process is very similar to carburising of iron to produce surface-hardened steel (iron heated with carbon particles for the diffusion to occur). Common processes falling in this category, are: aluminizing (calorising), chromising and Sherardising (zinc cementation coating), siliconising and borating. Processes like hot dip galvanizing, tinning, aluminizing and terneplating also form alloy, but technology is different from diffusion coating. Such alloyed coatings are used where high corrosion and abrasion resistance, in very active environments are needed.

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Metal cladding can cover a metal or other surfaces to form a barrier against corrosion. The thickness of a cladding metal could be few microns (metal leaf) to few millimeters (metal sheets or plates).

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Chromising is the term applied to the formation of a diffusion coating on iron or steel by chromium to produce a surface with enhanced oxidation, corrosion and wear resistance. Gas phase chromising is performed, when the articles heated in a powdered mixture of chromium, alumina or kaolin and an ammonium halide in a hydrogen atmosphere.

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DAY-LIGHTING – in Interior Spaces

Post 366 – by Gautam Shah

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Day-lighting or daytime natural illumination is an important requirement for Interior spaces. The illumination requirements vary for various tasks, background brightness (contrast or glare), forms of shadows, and movement or variations in levels of lighting. The direct sources of daytime natural illumination in interior space are openings like doors, windows, gaps, cracks, punctures, translucent or transparent walls, trellis, etc. Besides these there are number of indirect means that enhance or contrast the direct sources of illumination. These means are planer or curvilinear surfaces, reflective surfaces, colours and textures. The daytime illumination arrives to a built-form, from different directions and sources, such as directly from the source, from sky, and as the reflections from terrestrial objects. These sources include, direct sunlight, diffused sky radiation, and both of these as reflected from the terrestrial objects.

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The amount of daylight received into an interior space is defined as a daylight factor (being the ratio between the measured external and internal light levels). The external light level can be as high as 120,000 lux at noon for direct sunlight at noon, to less than 5 lux on very heavily cloudy evening.

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To gain maximum daylight into an interior space the building should have wider foot print and its perimeter should be linear or undulated. The building must be longer in North-South direction, compared to East-West direction, unless the space is meant exclusively for either Morning or Evening use. For Northern Hemisphere, North side and for Southern Hemisphere, the South side receives more daylight.

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The neighbourhood buildings and topography and immediate surroundings have a bearing on the quality of illumination entering a building. The reflected light from surfaces of buildings, colours of roads and pavements affect lower floors of the buildings. Reflections from sea front and movement of trees tops, due to the breeze, can have unsettling effect on interior spaces. Upper floors of tall buildings, except in similar localities, receive consistent, but very strong daylight from nominal windows. Such floors with bottom windows get disturbing reflections from traffic and other movements, reflected to the ceiling.

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Location of openings, their proportion to wall, and distribution, determine the distribution of day light in the interior space. In tropical climate zones and in colder climes during warmer months, open doors play a very important role in daylight gain. Similarly, open to sky Chowk or cutouts with surrounding passages or ‘livan’ like spaces allow distributed illumination.

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For good day lighting the interior spaces must have at least one face with exterior exposure, or with an abutting shading component like verandah or gallery. A skylight or upper level opening is an efficient source for natural illumination. A taller window leads the daylight deeper into the room space. The depth of daylight penetration is approximately two and one-half times the height of the opening.

High – performance glazing with downward inclination

The space planning of an interior layout must be optimized for daylight. Large tall pieces of furniture can act as mid space barricading element or as reflective surfaces. In commercial spaces half or fully glazed partitions can allow just sufficient illumination for passage areas. A plain ceiling at low level may not be as reflective as a stepped or contoured one.

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On exterior and interior sides use of light-shelves, against an opening, helps distribute the daylight and cut glare. A light shelf could be a small width blade of a louver to very large fixed or adjustable jalousie system. A high-performance glazing systems generally admit light without the heat gain.

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Reflectance of room surfaces impacts the perception of brightness in a space. The surface reflectance is a function of colour, its texture (matt, dull-sheen, glossy) and the orientation of grains of textures. Extreme levels of brightness are present in the same field of view, can be calibrated by surface design.

Ahwahnee_Dining_Room

Daylight must be planned and ‘attuned’ for requirements of tasks, posture, communication, expression and intra-personal relationships, Poor visibility, recognition, and discomfort result from lack of required levels of illumination, direction. To remove wearisome consistency (as with sky or high level openings), some variations in moment to moment daylight must occur.

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CARBON and STEELS

CARBON and STEELS

Post 365 ⇒   by Gautam Shah 

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Iron as a metal is very ancient material. It was difficult to process (smelt), unlike materials with lower melting temperatures, such as copper and its alloys. Iron is rarely obtainable in pure form. The impurities in iron derive from the ore, and carbon through the smelting process. Carbon is one of the most important of impurities, varying between 0.002% and 2.1%. Presence of Carbon makes the Iron up to 1000 times a harder material. Technically more than 90 per cent of all steels are carbon steels. Presence of small amounts of carbon changes the quality of steel. It affects strength, hardness, mechanical properties (machining, forming, etc.). With very high percentage of carbon workability and impact strength are reduced, whereas with lower carbon content hardness and tensile strength are higher.

Iron of meteorite -similar to Earth’s inner core

Iron ore pellets

Crude iron or Pig iron metal is produced in a furnace, by mixing ore with coke. The high carbon content of crude iron can be further reduced by refining it with air or oxygen, to turn it into steel. A carbon content metal is commonly called Cast Iron. The carbon content of cast iron is 2.1 percent or more. Gray cast iron is relatively soft. It can be easily machined and welded. It is used for engine cylinder blocks, pipe, and machine tool structures. White cast iron is hard, brittle, but not weldable. When annealed, it becomes malleable cast iron. Malleable cast iron can be welded and machined. It is ductile material. Ductile cast iron is sometimes called nodular or graphite cast iron. It is ductile malleable and weldable.

Iron Ore

Pig Iron billets

Besides carbon other elements present are, manganese, silicon, copper, nickel, chromium, molybdenum, vanadium, tungsten, tin, niobium, zirconium, and non metals like sulphur, phosphorus. These materials mostly find their way through the scrape that is partly used for steel making or through an intentional quality markup. The additions of these materials take steel to the category of Alloy steel. Such alloying elements are added to gain properties like better strength, hardness, durability, or corrosion resistance. These are often called specialty steels.

Crankshaft casting

Adjusting the carbon content is most common tool to control quality of steel. Other quality determinant is the rate at which the steel is cooled. Steel properties are also modified by heat treatments, mechanical working it at hot or cold temperatures and by adding other alloying elements besides carbon.

Steel with high carbon content is hard and strong, but not ductile enough for common uses. In carbon steels, the higher carbon content lowers the melting point and reduces weldability.

Mild steel bars

Low carbon steel has approximately 0.05% to 0.25% carbon content with other materials like manganese. Mild steel, is also known as plain-carbon steel or low-carbon steel. Its very common form of steel, and its material properties are adequate for many applications. It is ductile and malleable. It has a relatively low tensile strength, but is cheap and amenable to cold forming processes. Its surface hardness can be increased with carburizing. It is used for structural steel.

Steel forging

Medium carbon steel has approximately 0.29% to 0.54% carbon content (with 0.60 to 1.65% manganese content). It shows good wear resistance and used for large parts, forging and car parts.

High carbon steel has approximately 0.55% to 0.95% carbon content (with 0.30 to 0.90% manganese content). It is very strong material and used for springs and high-strength wires.

High end Steel – chef’s knife

Ultra high carbon steel has approximately 2.5–3.0% carbon content. These steels that can be tempered to great hardness and used cutting tools, knives, axles or punches. Steel with a carbon content above 2.14% is considered cast iron.

Clydach Gorge Iron Bridge Cast iron supports

Hardened steel usually refers quenched or quenched and tempered steel. Silver steel or high-carbon bright steel, gets its name from its appearance, due to the high carbon content. Silver steel is used for cutting edges and axle components.

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TAFFETA

Post 364 – by Gautam Shah 

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Taffeta is a high end or luxury fabric of Silk. It was worn by Persians since early 3rd C. Persians called it, taftah or taftan or taffian. It has been called taffety. The Persian word meant twisted-woven silk. Silk taffeta was once made from white silk cocoons. The taffeta making materials, their combinations, weaving styles, dyeing, printing and finishing procedures, all have been varying in different locations and times. But, all through history, in spite of many variations, it has retained its popularity for uses like women’s wear, bedspreads, dresses, drapes, lampshades, linings, trimmings, ribbons, corsets, etc.

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Winslow Homer Croquet Scene

Taffeta is tightly woven fabric and so has full body. Original taffeta is believed to be woven with equal numbers of warp and weft yarns. But in later periods, the proportions have been varied: with warp and filling threads, yarn-quality such as filament or staple, density of the weave. Other main effects included yarn-dyed and piece-dyed fabrics. Yarn-dyed taffeta has a stiff handle, and a rustle known as scroop, (Scroop -its synonym froufrou, is the sound that taffeta makes). It can be added to certain fabrics, by acid treatment that hardens the fibres of the fabric. Scroop is a desired effect of formal or evening dresses, and for undergarment-skirts for couture dresses of very thin or sheer fabrics like chiffon or georgette.

Jean Auguste Dominique Ingres princess Albert de Broglie

Taffeta being a silk fabric has a lustrous surface, but different texturizing, sizing and effects can make it a dull or slightly sheen fabric. Taffeta has an identical surface on both sides, and same texture from both orientations due to the same number of yarns in both directions. Some taffeta fabrics have fine cross ribs, formed due to the use of heavier Filling yarn than warp.

Woman’s plaid silk taffeta dress 1855

Faille Taffeta is cross rib weave fabric with a heavy and firm handle. It is woven with staple yarns. Moire taffeta or Moire faille has ripples which if heat set may not be permanent. Moire, French word meaning watered, once applied to lustrous fabrics of gold, silver and silk during 15th C. Today, it is used on synthetic taffeta as perma-set process. Paper Taffeta is a plain weave light weight material, treated to give a paper-like crisp feel. Tissue Taffeta is similar to paper taffeta but softer in feel and very light weight and transparent fabric.

Silk Taffeta dress 1865

Taffeta fabrics are given effects. Pigmented Taffeta is woven with pigmented yarns to make them almost an opaque or solid coloured fabric. Shot taffeta, Iridescent, Changeable or Chameleon taffeta, is a plain weave material, but with different colours for warp and filling. The fabric seems to show different colours in different angles of views. Warp-print taffeta is a plain weave, but the warp yarns are differently dyed in segments, or printed before the filling is inserted (similar to Patan, Gujarat, India, Patola Sarees). This gives a dazzling or fuzzy look to the regular patterns.

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Taffeta coutil is silk-cotton mix fabric, with lilac-white effect. Taffeta alpaca is similar to coutil but with black and white colour combinations. Fiantique taffeta has slub filler yarns and a near reversible look that imitates fine shantung. Taffeta angleterre is a highly glazed and stiff material used for, caps, hats, form-effects and for curtains and for billowing the dresses through stiff lining.

Taffeta fabrics were favoured for offbeat uses till arrival of Rayons, Nylons, Polyester and glass-fiber fabrics. Taffeta fabrics were used for electrical insulation, parachutes, making air-balloons and very light air craft. Synthetic taffeta like fabrics, mainly of polyesters are used for different purposes ranging from garments, industrial to built-forms. The uses include dresses, dresses for performance, stage curtains, tents, partitions, air structures, umbrellas, soft luggage, and as an insulation and lining fabric.

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MAINTENANCE versus REPAIRS of Buildings

MAINTENANCE versus REPAIRS of Buildings

Post 363 ⇒   by Gautam Shah 

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To maintain a building means, in literal sense is, `to preserve from loss or deterioration‘. Maintenance is the act of maintaining, supporting, preserving, continuing, and defending. A Repair means, to mend, to restore, to revitalize, restoration after injury or decay, reinstatement of loss. Maintenance is preventive in nature, compared to Repair which is a corrective action.

Well -Baoli Ghaus Ali Shah, Farrukhnagar

Buildings with adequate or timely maintenance require lesser repairs in extent and frequency. Unrepaired buildings decrease the efficiency of maintenance. Maintenance is not designed to change the building.

B.S.3811 (1964) defines maintenance as: ‘A combination of any actions carried out to retain an item in, or restore it to an acceptable condition’.

To retain

–preventive maintenance

To restore

–corrective maintenance

Acceptable condition

–to the person paying for the world

–to the person receiving the benefit

–to someone outside enforcing minimum standards

–to society in general.

Mud plaster requires frequent maintenance

Maintenance techniques are employed for two ends: Improvement: superior to the original design standards, and Restoration: equal to the original design standards. Where the design requirements are stated in the form of parameters or specifications of performance, these could be used for establishing the maintenance standards. Performance requirements need to be incorporated in the maintenance manual concurrently with other explanatory details about the building and its services.

Taj-ul-Masjid Gates Bhopal Madhya Pradesh India

Planned maintenance is an organized effort carried out with forethought, and control. It is to be conducted regularly but must accompany all major changes in the building. As a forethought out action it is apparently well documented.

Preventive maintenance is carried out at predetermined intervals of time or use cycles. It is also initiated by professionals, as soon as minor decadence is noticed.

Minor repairs with regular maintenance

Running maintenance occur on regular or continuing basis, in the form of running a plant, or as a service for a running system. These take the form of nominal activities like cleaning, waste disposal, oiling, fuelling, cooling, warming, etc.

Thatched roof maintenance

Buildings, consist of both, physical and metaphysical things. Maintenance means continuing the physical entities, by removing decay causing elements including replacing the warned parts and components. Metaphysical things like image, tradition, fashion, etc. are maintained by adopting incorporeal or pseudo means. In a building, the maintenance strategies of realist and absurdist nature operate concurrently.

Elgin Cathedral choir wall -need for repairs, maintenance and conservation

Actuators for maintenance are both, internal and external to the building. Externally the climate has the greatest effect, though varying in severity according to the orientation and location of the building. Internally the user and activities affect the building. The actuators of these effects are also mutually dependent. Changing life styles, living standards and economics affect the nature of maintenance. Buildings where quality of space determines the efficiency of work activities, and which in turn scales the economic returns, are well maintained.

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COOKING and DINING

Post 362 – by Gautam Shah

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Kitchen and Dining adjacency

Kitchen and Dining adjacency

Cooking and Dining, have been conjunct areas. Dining is intimately related to the food preparation activity. Dining area has been shifting close and away from cooking area. The reasons are due to environmental, ethnic, social, religious, organizational and technological reasons. Cooking and dining, originally flourished, in the same space segment; separated in the middle ages, and once again merged during the last century. The dining, however, is now poised to supersede the kitchen or cooking. Dining itself may become a food ‘preparation’ area.

Modern Design Residential Counter Kitchen Interior

The Kitchen-dining, have had varied proximity mainly due to the environmental factors. Cooking areas in all climate zones were untidy and uncomfortable due to heat, smoke, and soot, all due to poor quality fuels. To compound these odours of food preparation and garbage, were not easily manageable. In tropics it was possible to prepare food in open or semi-open spaces, but in colder climates environmental control was dependent on chimneys or roof holes. Natural illumination was another concern in absence of glazed openings. Cooking and dining, still remained adjunct to each other in all climate zones. In smaller dwellings, both remained in the same space, but in large mansions the retinue of servants mediated the separation.

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Johann Heinrich Sturmer Kochin Wikipedia image

The dining area has had many different forms, depending on the nature of food, schedules, moods, companionship, sex, age and social standing of the diners, ambiance of space, and other engagements. Dining consists of morning tea, breakfast, lunch, brunch, afternoon tea and snacks, supper or evening meals, or late night caps. These are taken in different sections of the house. The settings for food consumption ranges from a stiff dining table to an informal verandah, nurseries, terraces, home garden, to very intimate one in bed.

Small kitchen

Small kitchen

Small houses due to space restraints may combine food preparation, cooking and dining to same section of the space and share the amenities. Urban families stay in smaller houses where dining is more of the functional need without any scope for social interaction. The busy life styles, (working husband and wife, other adults) does not permit extensive cooking at home, or have frequent dinner guests. A bar platform, once an intervening element between the kitchen and dining or the extension of a pantry, meant for brunch and fast-track meal; now began to replace the formal dining space and table. The functional bar like a platform with tall stools, allows one to have a quick-bite in a standing or semi-siting position. Such small dwellings and single person units do away with the formal dining table or a designated space.

Kitchen and dining

Kitchen store room

Indian Kitchen Pantry + Store Room

The kitchen and dining were once separated through a pantry. The pantry and store rooms began to be useless for several reasons, 24×7 hours assured supplies, smaller size of family and less frequent partying at home. The kitchen-dining also began to be connected through a door, often double leaf glass doors. The kitchen-dining connection was further dilated with removal of the mid-barriers. An exclusive kitchen conceded the living room (family room) to the drawing room, but a living room, well integrated with the kitchen, allowed the drawing room to exist on its own -a secluded space.

Kitchen – Dining – Family room –as one space

Dining room is merging into the kitchen for other reasons. For husband and wife as a working couple find the combined kitchen and dining with better chance of communication, for being together, and enjoy the soap operas.

Kitchen - Dining connection --double leaf glass doors

Kitchen – Dining connection –double leaf glass doors

Food preparation cooking, serving, and dining, were all well delineated in terms of the purpose, place and space. But these have been changing. Modern homes subsist on pre-cooked, preserved, ready packaged foods. These require warming in a microwave and the serviettes, dishes, bowls, tableware, are disposable. The working person has lunch at the workplace, and dinner in a restaurant. The kitchen and dining are deprived of their core functions.

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EXPRESSION and SPATIAL BEHAVIOUR

EXPRESSION and SPATIAL BEHAVIOUR

Post 361 ⇒   by Gautam Shah 

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Expression is intentional and involuntary, and together reflect the human behaviour. Both types of expressions, though occur under certain protocol and situational conditions. For both manifestations one exploits the spatial assets and environmental provisions. Expressions also take advantage of functional elements such as the reach tools, amenities, facilities and structures. Modification of such existing conditions is also an expression of behaviour. Expression is aided by many conditions. The characteristic style of architecture and the interior configurations inspires many to express. The environmental conditions like, illumination, acoustic and comfort affect the nature of expression.

Three generations of Women

Intentional expression is personal process, and is in consideration of the others, but involuntary expressions are not meant for anyone. Intentional expressions are acknowledging the physical characteristics of the participants such as age, sex, experience, body posture, mental adequacy and maturity, time and distance, nature of need, compulsions, disposition, etc. The involuntary expressions are so subtle, casual and sudden that neither the person expressing or the party perceiving it, fails to notice it. Both types of expression are a way of venting the emotions. Involuntary expressions have very complex origin, not all aspects of it have yet been known.

Expressions occurring through the body’s gestures and postures, are perceived by others. However, one may try to conceal or suppress such a display. Expressions are sometimes masked or moulded by postures and gestures, and also with the help of spatial characteristics, architectonic entities, environmental elements, amenities and facilities. Expressions can be also time-managed by rescheduling that is hastening or delaying the effects.

Intentional expressions have a purpose of informing, recording, recollecting, inciting, convincing, putting forth an argument, generating feedback, forcing showing feelings, ideas, thoughts, opinions, re-experiencing, recollecting, abridgement, elaboration or re-enactment of a happening.

Expressions are aided by the contextual conditions like spatial form, shape, size, scale, environment and surface materials. Other aids include referencing through position, orientation, background vs foreground, angle and nature of perceptibility, degree of sufficiency for various body functions (reach capacity, comfort, metabolisms, etc.). These aids simplify, amplify, de-intensify, amalgamate, compact, quicken or retard the rate and contents of expression. In absence or dilution of these ‘effects’ the expression may not be very operative.

Gestural expression -Intentional

One may make an intentional expression by using body gestures and postures, but additionally support it by other sensorial means like vocal and touch. Non-personal or absentia expressions through remote means like telephone, broadcasting or publications use various means of emphasis (or even diffusion) (repeat, highlight, placement, emphasis) to support the expressions. Like for example, speaking face to face or frontal-way is a very direct but can be diffused by slightly off-centric or angular dealing. Similarly a superior delivery position, a static and clear background, appropriate lighting, clothes, etc. reinforce it.

‘Classical’ expressions occur within a geographical-social-political group due to the very intense and frequent usage. These are abstract and brief due to their heavy reliance on metaphoric vocabulary. Expression as an impromptu process is accompanied with use of learnt or improvised behaviour. ‘One emulates a child by mirroring the behaviour’. Expression during the interactions, are affected by the modes of transactions, such as one way or two-way, or multiple ways, and by use of feed-forward and feedback mechanisms. Intentional expressions get improvised the moment a perceiver shows reactions.

Expressions for aesthetic satiation are always intentional. Expression for aesthetic satiation occurs through representative forms like singing, writing, art, craft, etc.

The Crown of Thorns by Matthias Stom

Expressions process let a person to organize and rationalize the thoughts, and format the contents. The act of expression also allows recognition of time and space. It allows one to emphasize and de-emphasize whole or parts of the content.

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