Post 371 – by Gautam Shah



Floor paints constitute a distinctive category of Architectural coatings. Floor paints are broadly of three classes: Clear coatings, Pigmented or coloured paints and Technical coats. Technical coats could be under coats, super coats or singular coats. Floor paints or coatings can also be differentiated in terms of their placements: such as for top of the roof, under coating for the roof, exterior and interior surfaces of wood or masonry materials, and technical coats for floors of water storage (tanks, moats) and channels (aqueducts and canals).

5331087042_92dc21010d_zFloor paints are used to improve the appearance, increase abrasion resistance, reduce moisture penetration and impart spillage proof qualities. Floor paints, nominally do not include coatings or applications with substantial mass such as various types of plasters or depositions. Some screed applications have dual classifications of floor plaster as well as a thin coating system. Floor paints are thin surface coatings, applied on variety of substrates and with equally varied methods.

pexels-photo-122480Ancient floor coatings were applications of oil mixed with wax, bitumen and creosote. These were used for treating floor decks and seats of seagoing vessels, sea coast wood structures, wood floor boards around wells, and underside boards of roofs over purlins prior to covering with metal sheets or ceramic tiles, all to prevent the rot. Oil-wax was used, for floorings and stage floor boards, to keep intact the visual appearance of the wood. Bitumen and creosote darkened the surface and often remained tacky (due to addition of tallow or fish-oil), but wax-oil coatings, with higher content of wax were non tacky. Wax was hot-melt in bodied oil (double boiled linseed oil or polymerized oil) or oils modified with Pine-rosin. These formulations were nearly like Varnishes used for coating furniture or covering the paintings. The surface had gloss and smoothness. The Varnish coatings lasted a year or one wet season, and required re-application.

Stornoway_Airport_RunwayAncient Floor coatings were mainly applied on wood surfaces, but occasionally dull floors of stones were given a coat to achieve a shiny surface. Dull stone floors of sandstone or lime stones were coated for festive occasions like coronation, marriage and religious functions. These were temporary applications, and no one was bothered about its durability or issues of re-application.

Vera_Project_12The floor coating system saw renewed interest when large size merchant and cruise ships, railway coaches and passenger bus vehicles arrived on the scene during the Industrial age period. These utilities did not have masonry or wood floors. It was necessary to create decks of colourful ambiance, and of wear resistant, non-skidding, sound dampening and maintainable material. The first options then available were linoleum carpets and alkyd-based enamel paints. Both created floors with fewer joints, but paint was a re-applicable surface.

Akshardham temple-931709-1

1024px-Cameron_Indoor_Stadium_interiorRoad and surface signage and functional graphics became a necessity, with the increase in road and rail traffic. There was no space in many urban areas to place vertical signage. The floor signs painted on roads and pavements were warnings in the movement spaces, passengers’ zebra crossing marks, edges of surface drops, road segmentation, danger zones, curvature limits. These were initially by contrast colour paving. Similarly barefoot walk-passages in temples, mosques needed a lighter colour treatment to keep them cooler. The only option, than available was to use lime whitewash or alkyd based white oil paints.


Resort Santorini Greece Building TerracesIn post world war period plastic (or Latex, as known in USA) paints became available. The ‘latex’ paints were water-based emulsion medium. The field of marine coatings was offering many new technologies for water and UV light resistant, hard wearing systems. Rubber-based systems (chlorinated rubber coatings) became synonymous with road marking paints.


Other fields of Indoor floor paints were emerging. Stage show floors, Dance floors, TV programme production sets, TV News room floors, sports arenas, required colourful joint-less extensive surfaces. Food plants, Pharmaceutical units, Hospitals operation theatres and critical care areas, needed not only a joint-less surface, but one that was dust and scratch proof and bio-friendly material. These were first provided by Polyurethane systems and later by Epoxy systems. Electronic assembly plants, computer rooms, electronic exchanges and data server and router areas, needed static proof floor coatings. Fire-prone industrial areas needed a spark erosion flooring systems.

indexOutdoor Floor paint field also has flourished well. Sports facilities, stadiums, exercise areas, malls, food plazas need many different types of a joint-less floor of non skidding and spillage proof surfaces. The colour and texture requirements of these usages can never be found in any natural or manufactured materials. Thin coating systems of floor paints not only satisfy such unique needs but also offer pattern laying facility.

mark-1105984_640Technological innovations include use of Florescent pigments, night glow compounds, high luminescence whitening agents, texturizing additives, wrinkle finishes, two or multi-tone effects.

640px-GeneDavisStreetThe ability of a floor-painted surface to virtually do everything expected of a floor system, has forced changes on substrate technology. There was a time natural floor materials like stone or ceramic tiles were ground to smooth level and then coated. Any joint gaps or remaining surface level irregularities were filled in. But now cast on site surfaces of many materials are preferred. The material options include Ironite (cement+sand mixed with iron turnings), Magnesium Oxy-chloride Flooring, Cement Concrete floors (Tri-mix suction system), etc.




Post 370 ⇒   by Gautam Shah 


Ventilation requirements and modalities for Buildings in tropical climates are very different from buildings of cooler climates. For buildings’ indoor climate four important issues are heat, moisture, air movement and contaminants. Of these four, the Heat needs to be removed, Moisture conserved or scrubbed off the air depending on dry or a humid tropical zone, Air movement encouraged, as it positively impacts the rest of the three issues, and Contaminants including CO2, CO, odours, and airborne particulates diluted.

The removal of heat from an interior space is a contradictory concept from heat conservation, being practised in buildings in colder climates. Moisture management in a tropical climate is mainly with the concept of comfort, rather than environmental damaging factor. Effective air movement take care of heat from body, evaporative cooling of perspiration and free moisture, and removal of odours and other contaminants from space pockets.

Hubei Yichang Village

Ventilation in a building in a tropical climate zone occurs in many different ways. Openings like doors and windows remain open for substantial part of day-night period (except at nights and in few winter months), providing air-change. When the openings are shut, the cracks, crevices and structural micro gaps (such as thatched roofs, terracotta tiles, etc.), provide ventilation needs. Cracks and gaps, are usually insufficient for heavier needs of ventilation for toilets, kitchens, production areas and public spaces. Cooking, bathing, washing, require intensive ventilation, but in many tropical dwellings these occur in outdoor areas or distinctly adjunct spaces. Where climates are benign, intensive outdoor home or public life trims the indoor ventilation requirements.

Bundi Street Rajasthan, India

Historically Government offices and administrative posts in India and Asian countries have relied on two architectural provisions for climatic comfort: High volume (tall spaces) rooms and Verandahs for conducting their businesses. Concept of cross openings (opposite ends) in buildings has been a natural practice. In Iran, stack-effect through towers and water bodies, both have helped ventilation (air change) and moisture addition. Spaces like Livan has been a feature of Mideast dwellings.

Wind Towers Dubai

In western countries, such as Europe and US, ventilation requirements are specified in terms of air changes per hour, ACH where entire interior volume of air must get replaced per hour. But this is presuming a room to an enclosed (sealed) space in colder environments. This concept is universally applicable (in all types of climates), to an extent, for air-conditioned urban buildings.

Outdoor air at any location is relatively less polluted because it has greater scope of dilution compared to any restricted interior air mass. However, in dense urban localities and at locations near known pollution activities such as power plants, industry, open mines, etc. outdoor air can be a source of pollution. High level of humidity in certain coastal locations, and during very heavy rainy seasons can be considered a contaminant of air. Where such air is used to replace the interior air, some control or processing by passive or active filtration devices, integrated within the opening system are required.

Courtyard Cuzco

NATURAL VENTILATION: Natural ventilation advantageously uses wind movement speeds, pressure-driven flows, and temperature differences (stack effect) to supply and remove air through enclosed space. Windows placed on opposite sides and on same axis are better ventilating device. The position of window vis a vis the work plane or task is determined weather one wants a draught-breeze over the body and the task or avoid it. The nature of shutter opening also determines the direction of the internal air movement. Air moves because of differences in temperature and pressure across the supply and exhaust points. In single storey houses, the movement of air due to pressure differences is main factor then the differences in temperature across the supply and exhaust points. A high-pressure area occurs air strikes a building and low-pressure areas are created as the air moves over and around the building. To encourage movement of air within a room, the openings, through which the air leave should be larger, than those through which it enters. The direction and strength of air movement are altered due to draperies, furniture items, people, local heat sources (heating, cooking, machines) and air movement devices (fans).

Shan Ha Wai or Walled Village at the Mountain’s Foot, is a Hakka walled village in HongKong

TRANSFER VENTILATION: Movement of air between indoor spaces, and not the outside, is called transfer-air. It has, though limited a role in ventilation, but is a great tool for thermal comfort. This concept has been in use in traditional tropical homes and settlements. Interior space modules are mutually connected through openings, exposed to space ingresses such as cutouts, Chowks or courtyards or are exposed to an exterior face. At a settlement level several buildings share community spaces for transfer ventilation. The openings nearly remain open or are latticed. The buildings are closely spaced, so few sides are exposed to sun.

Kapali Carsi Grand Bazaar Istanbul -Transfer ventilation

Transfer air ventilation for interior spaces work best when spaces are used at different times of the day, for different tasks and by varied occupation (number of space users). Transfer air ventilation combines horizontal flows and vertical stack effects.

Koothambalam at Kerala Kalamandalam

VENTILATION and OPENING DESIGN: Windows with shutters opening outward often obstruct the wind path, but double hung sash windows and sliding shutters which open within the frame are better as receptors. Casement window shutters with offset hinges or friction stay which create a small gap on the jamb side help in catching the breeze. Hoppers, awning and jalousie windows direct the breeze due to the angle of opening. The depth of a window and its surround also affects the nature of ventilation. Splayed sides create funnel effect to catch the breeze.



Post 369 –by Gautam Shah


Design processes involve Decision Making. Decisions are taken on factors that are essentially part of the project itself, and also on various presumptions, which may or may not become part of the project. In the first case the decisions are made on factors that are internal, through a process of selection, confirmation, elimination, etc. While in the later case, the decisions are made from external factors, where not only the relevance, but the entire range of their effects needs to be forecast.


Decisions are primarily taken when an action is required, or when further decisions are due. Decisions are taken at: conscious level (intellectual) and subconscious level (intuitive). Actual time and exact place of a decision cannot be identified. However, the context within which certain decisions are made can be known.

Decisions are taken through:

Analysis: Dissecting a whole into parts so to understand it better.

Synthesis: Combining several things to form a whole to see if it is pertinent.

Holism: Conceptualizing the whole thing.


The quality of decision is governed by the decision makers’ (design professionals’) state such as: physiological fitness, mental alertness, personality traits (daring, fear), information, training, experiences, opportunities, time, resources (human, equipment, finance, circumstances), etc.

The gut-feeling (Forbes)

Decision making helps a designer with an analytical base to affirm a belief (intuitive or ‘gut-feeling’) and select a course of action from several nearly equal alternative possibilities. Decisions do not have mathematical sharpness or uniqueness. There is never a perfect decision. There usually are many different ways of achieving the same goal. A decision is a subjective process that offers the best course for a given situation. The situation here could be the mental condition, exigency or compulsion. Actualization of a decision may include course corrections. Because the original decision making moment and its conditions change by the time actualization occurs. Efficiency of a decision is judged, on how much it accomplishes and in what time. A reasonable decision always takes one closer to the goal, however, slightly.


Decision makers ask questions like:

Is the objective defined ?

Is sufficient information available ?

How many options are available ?

Have these options been evaluated ?

Are all risks identified and provided for ?

Does this decision feel right, now that actions are being taken on it ?


Decision making and consequences thereof (actions or further decisions) are often so interlaced that it is not possible to view them separately.

Decision making comprises of:

1   forecasting the most opportunity moment and the most obvious context, for the consequences to occur or even not to occur.

  determination of probabilities of occurrence or follow up actions.


Another article (detailed) on same subject >> https://designacademics.wordpress.com/2016/10/16/decision-making-and-problem-solving-22-design-implementation-processes/


FIBRES for Fabrics

FIBRES for Fabrics

Post 368 ⇒   by Gautam Shah 


A fibre is a flexible linear entity with very small section compared to its length. Fibres are of natural plant or animal origin, or synthetic products. Fibres are used for spinning into yarn, forming threads and ropes. Yarns are used for weaving or knitting into fabrics. Fibres of plant origin, like cotton is pure cellulose and used for production of paper and other cellulosic compounds. Fibres are massed (without any weaving) to form padding materials, filter media, blankets and mattresses. Fibres and their products are also used as reinforcements and as the fillers in formation of composites.

Polyester Texturized Yarn

A fiber is characterized by its length which is as much as 100 times its diameter or width (10 µm -width of cotton fibre). Fibres do not have consistent section along its length. Fibres of natural origin (and synthetic fibres that has been cut) are short, called staples, whereas silk and synthetics are long length fibres, called filaments. To spin fibres into a yarn, the lengths should be minimum 5 mm. A typical yarn could have more than 30 fibres. To spin a yarn fibres must have flexibility, texture, cohesiveness, elasticity, fineness, uniformity, durability, luster and sufficient strength for spin-twisting. A variable cross section gives (longitudinal structural elements -fibrils) textural effect to the fabric. Fibres that cannot be split longitudinally are called elementary, and when several such elementary fibres join longitudinally to form conjugated fibres. The length of the fiber affects the appearance of the yarn and the quality of the fabric. It is easy to produce a smooth yarn from a filament compared to staples, which require greater amount of the twist. Yarns made from the filament have greater luster, but yarns made from staple fibres have a dull appearance.

Cotton fibre under scanner

The quality of a fabric is largely related to the physical characteristics of the fiber such as:

Colour: Colour of the natural fibres varies; however darker shades can be lightened by bleaching and than a uniform colour can be applied.

Luster: Luster is the amount of light reflected by the fiber. It is both a desirable and undesirable property, depending on the type of use-conditions. Man-made fibres generally have a high luster, which can be reduced or de-lustered by incorporating titanium dioxide in the manufacturing process.

Silk from cocoon is a fine filament fibre -several of these spun into yarn – dyed -ready for weaving as hanks

Shape: Shape relates to the shape of the cross section of the fiber. In case of man-made fibres, it is very uniform (unless further processed by ‘texturizing’) over the length, compared to a variable cross section of natural fibres. Cross sectional shape affects the appearance, feel, surface texture, body, covering power and luster. Round sectional fibres have soft, smooth and slippery feel, high luster, poor covering, and close packing. Dog bone shaped and flat section fibres have a harsher, less smooth handle, good covering and high luster (except cotton). Fibres with multiple lobes in cross section have high covering power, silk like feel, high luster and sometimes soft subdued sheen. Hollow fibres are made by dissolving the inner core material and have high bulk but low weight, fluffy. Such fibres are insulative and absorbent.

Hand spun llama yarn

Surface contour: Surface contour of the fiber in length is smooth, rough or uneven. Wool is covered with small scales that make the fiber cling together, cotton has twisted surface, that reflects the light unevenly and imparts a dull appearance. Manufacturing characteristics and irregularities appear on man-made fibres.

Magnified fibers of (a) silk (b) wool (c) cotton

Crimp: Crimp is an undulating physical structure. Wool has a natural three-dimensional crimp. Most man made fibres are either produced with a crimp or texturized. Fabrics produced from crimped fibres have increased bulk, cohesiveness, warmth, false absorption and better resiliency.


Types of Fibres and Yarns: Fibres are spun into yarn. Yarns are uninterrupted threads of textile fibres that are ready to be turned into fabrics. Natural fibres originating from natural sources are: Plant (cellulosic), animal (protein). Manufactured, synthetic, or man-made fibres originate from chemical sources or could also be from regenerated or recycled sources.

Aramid Fibers



Post 367 –  by Gautam Shah 


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.



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.


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 appliqué coating like paint or an integrated one like plating or galvanizing. Integrated barriers are also formed by metallizing, 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.


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.


The oxide layer that forms on metals when they are exposed to air also constitutes a protective barrier. Bronze, Stainless steel and aluminium form the most stable and protective of such films. The thickness of the oxide film on aluminium 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.


Galvanic protection: Appliqué 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 appliqué 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 aluminium-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.



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 aluminium chloride.



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


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

Chromatizing 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 (calorizing), chromatizing and Sherardizing (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.


Calorizing is an industrial surface modification process used to create aluminium diffusion coatings. Calorizing is performed by diffusing aluminium into steel. This process forms an alloy with ideal heat and corrosion resistance properties.


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).


Chromatizing 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 chromatizing is performed, when the articles heated in a powdered mixture of chromium, alumina or kaolin and an ammonium halide in a hydrogen atmosphere.


DAY-LIGHTING – in Interior Spaces

Post 366 – by Gautam Shah



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.


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.


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.


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.


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.


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.


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.


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.


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.





Post 365 ⇒   by Gautam Shah 


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.



Post 364 – by Gautam Shah 



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.



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.


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.



MAINTENANCE versus REPAIRS of Buildings

MAINTENANCE versus REPAIRS of Buildings

Post 363 ⇒   by Gautam Shah 


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.



Post 362 – by Gautam Shah


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.


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.


171115-F-AL359-9996 - rotator