Post 553  by Gautam Shah



Paints have colourants or pigments to cover a substrate and provide new colour. Pigmented coatings constitute the largest section of coating production. Clear coatings, however, provide a see-through film on a substrate, which in additionally endow spacial surfaces, textural and other properties. Clear and pigmented coatings have been concurrently in use since prehistoric times. Both types of coatings usually have similar film forming substances, though the techniques of application and purposes these are employed are distinct. Pigmented and clear coatings, both can form the primer coat or a top coat in a multi coat system. As a primer or first coat the clear coat penetrates micro pores and seals the surface. As a top coat a clear finish endows specific surface quality such as gloss, sheen or matt finish and protection. In a multi coat system a pigmented undercoat creates a colour-equalized surface.


Pigmented coatings, besides colourants like pigments and dyes, have many other substances that add special effects through opacity. These are metal powders and flakes, prilled materials, micro sized lints of glass and polymer fibres, glow powders for phosphorescent, luminescent or photo-luminescent effects. Pigmented coatings usually contain extenders for several purposes. Extenders are minerals of low refractive index. Pigmented coatings for rendered or textured finishes have high solid build resins, additives or false viscosity enhancers and minerals and fillers.


Clear Coating of Shellac Wikipedia image by Simon A. Eugster

Clear coatings are translucent to transparent, which are natural properties of the resin (film forming substance) or through additives like dyes and very low refractive materials. The need for a clear coating could be functional, such as avoidance of pigment for being unnecessary, toxic, or reduce the bulk of the film and thereby better homogeneity and lesser thickness. Clear coatings offer glossy to dull types of surface textures, and provide shades like tinted, crystal clear or water white. Surface texturing like hammer-tone, wrinkling, crackled, streaking, are also achieved. Clear coatings applied to emphasize substrate colours, grains or patterns as in case of timber, leather, paper metals or fabrics. Clear coatings are applied where for any technical reason it is not advisable to colour a coating, as in case of toys, food cans, etc. Large number of clear coatings are technical applications for rust inhibition, water proofing, static resistance, etc.

Surface Dark Wooden Table Wood Timber Texture

Some of the crudest forms of applying clear coatings, are still practised, and these are surface wetting with plain water, waxes, oils or tallow surfacings, starch sizing, gum and other plant exhudents surfacing, milk, and casein coatings. These materials are hydrophilic, and many run in moist weather, collect dust and are vulnerable to fungus attack.

Painting road markings

A better alternative for creating clear coating, has been the use of distilled and modified pine tree extracts like rosin. Calcium and zinc modified rosins which are soluble in turpentine were used for cheap quality toys, country furniture and electrical wooden boards and battens. Often raw senna, umber, ochre and dyes like metanil yellow are added to these for colour toning and hide the ugly grain and defects of jungle woods. The finish has very little resistance to wear and tear and slightly softens up in moist weather.


Pigmented coatings are used on sites, in industrial production units, by amateurs, artists, and crafts people. These coatings are applied with crude or rudimentary methods and also through high-tech facilities. Pigmented coatings contain specific minerals and other substances as pigments and extenders for rust inhibition (zinc), water resistance, electrical properties and fire resistance (such as walstonite), anti fouling agents.


Wikipedia image by Baminnick


Pigmented coatings are of following basic classes:

1. Architectural finishes


  • Water-based masonry finishes
  • Other masonry finishes
  • Non masonry finishes applicable on sites

2. Industrial finishes

  • Solvent-based systems
  • Water-based systems
  • High solid coatings and powder coatings
  • Air drying systems, Low and High Temperature baking systems, Catalyst systems

Vehicle Automobile Paint Body Repair Auto Car

3. Other types of pigmented Surface Finishes and Treatments

Marine Paints

  • Marine coatings
  • Road marking systems
  • Toys’ and plastic colours
  • Leather colours
  • Body colours and make-up utilities
  • Inks




Post 552  by Gautam Shah



Nepal painters Flickr image by Wonderlane

Coatings are selected in consideration of the substrate (virgin or already coated surface), application technology and atmospheric conditions. Commercially coatings are available for broad categories of surfaces, such as masonry, wood, metals; for specific layering such as primer, undercoating, top or finishing coating; for purposes such as architectural, industrial, marine, clear coatings, food-grade; for technical applications such as water-proofing, insulating, mastic compounds, fire-retardant or proofing, conductive or anti-static etc.


Wikipedia image by Biswarup Ganguly

Selection of a Coating is done in view of following factors:

  1. Appearance (colour -hue, tone) (texture -sheen, gloss)
  2. Weather properties
  3. Abrasion resistance
  4. Adhesion to the substrate
  5. Impact resistance
  6. Flexural qualities
  7. Recoatability
  8. Drying time (touch dry, hard dry or use ready)
  9. Feasible drying techniques ( Air dry, baking, catalytic)
  10. Resistance to a given medium (sea water, alkaline or acid, chlorine and sulphur)
  11. Resistance to sunlight (direct sunlight and UV component)
  12. Antistatic properties
  13. Temperature resistance
  14. Odour
  15. Solvent vapour hazards (VOC)
  16. Ecological value
  17. Application environment (open, enclosed, controlled, inclement)


Wikipedia image by Vermont Timber Works Inc.

General Rules of application

Many of these rules are more pertinent to Alkyd resin-based coatings, rather than Latex or Plastic polymer-emulsion-based coatings. Both often contain anti-settling agents that retard the separation of solids from liquid components. The Plastic paints now contain thixotropic agents that induce false viscosity when the coating material is at rest, but once stirred temporarily gains normal or applicable viscosity.

1 The tins, drums, carboys, Jerry-cans of coatings, primers and undercoats should be delivered on a site, at least 24 hours before the job and allowed to rest, and revert to the site temperature.

2 All packing of coating materials, except solvents, should be placed upside down for at least 24 hours, prior to the job (relevant for An Alkyd resin based pigmented coatings or oil paints, primers etc.)

3 Always draw just sufficient material that can be used immediately (-if enamel, preferably within an hour, and, -if lacquer, much shorter duration).

4 Do not pour back any colour that has been drawn out and exposed to the atmosphere. Before closing a partly used tin, pour a small quantity of miscible solvent or thinner over the surface to prevent skinning and evaporation of volatile substances.

5 Atmospheric conditions should normally remain consistent (ideal temperature range between 10°C to 35°C, humidity 50% and breeze velocity at 20 km per hour) for the entire duration of application, and curing or drying. The surface to be coated must be at the ambient temperature. All direct sun-rays (even for exterior coatings), except of the early morning, should be avoided for the entire period of application and till the coating is `touch dry‘.

6 Tint the undercoat slightly lighter than the final coat to differentiate and ascertain the full coverage by the final coat.

7 Where very light shades (`off whites‘) are to be mixed on a site, first reduce the tinting-paste with a small amount of white paint, and then adjust the final shade with the reduced tinter. To match a very light shade, place a drop of mixed trial colour on white paint wet-surface, and judge the difference. Certain high tinting pigments, such as blue, black and red are required in extremely small portions, and are difficult to mix in base white or lighter shade. Such coatings turn out to be slightly darker and sometimes have streaks, because brushing or rolling enhances the dispersion of pigments. To avoid this it is better to filter out all the site-mixed colours with a Nylon or Polyester fine-mesh cloth (bolting cloths, used for making screens for screen printing).

8 Water based coatings, dry out to a lighter shade then their wet look and Oil or resin-based coatings dry out to a darker shade then their wet look.

9 Never apply a very thin coat, or a thicker coat, than recommended by the manufacturer.

10 Apply the first coat in the direction of fibres or texture grains of the substrate. Apply the next coat in the cross direction, observing that the final coat on vertical surfaces is always in a vertical direction. It is always better to apply the final coat in direction of length then width.

11 Allow sufficient time for each coat to thoroughly cure or dry out, before any new coating or treatments (like sandpapering, rubbing) are done. Learn to differentiate between a `touch dry’ and ‘through dry’ conditions of a coating. Convertible coatings1 should not be re-coated before these are thoroughly dry, but Non-Convertible coatings2 can be re-coated when substantial part of solvent material has evaporated. Non convertible coatings can develop an inter layer adhesion. Both types of coatings, though may not be brush coated before through drying. Non-convertible coatings, however, may be re-coated by spray method.

12 Allow sufficient time before the coated object is used for intensive service (quite often it may take 7/15 days after `through dry’ conditions), because it takes longer for the inner section of coating to become thoroughly dry.


Marine Painting

*(1) Convertible Coating > The film forming substance on drying or curing coverts itself into a different material, which cannot be reverted by any process like solution, heating, etc.  Dried out Oil paints cannot be dissolved.

*(2) Non-Convertible Coating > The film forming substance on drying can be reconverted into original like material by solution or heat softening. NC Lacquers are such coating materials.



Post 551  by Gautam Shah



Daylight has Four important facets, the illuminance, warmth, colour and the variability. Each of these becomes a key issue for building design, how we conduct tasks and manage comfort. The chief source of daylight is the sun. It offers direct and indirect (‘diffused’) light. The earth’s daily rotation on inclined axis and elliptical rotation around the sun offers the variations, beyond the frequent changes in sun’s own output. Sunlight at Earth’s surface is around 52 to 55% infrared (above 700 nm), 42 to 43% visible (400 to 700 nm), and 3 to 5% ultraviolet (below 400 nm) spectrum. The quality of daylight at each place and moment is distinctive, creating unique time, space and environmental combination.



Grand Station NY The natural flood of daylight is no longer available due to  high-rise buildings in the vicinity

Daylight is the combination of all direct and indirect sunlight available outdoors during the daytime. Daylight as a natural light is considered mainly during the sunup to sundown period (and little more for the twilight periods). The amount of natural light available in any interior space is proportional to the daylight available outdoors. Daylight on an outdoor location is a combination of direct sunlight, diffuse sky radiation, and both of these as reflected from the earth and other objects. Light scattered in the atmosphere is referred to as diffused daylight. Sunlight scattered or reflected from other space objects, such as the moon is not considered daylight.


Lighting without a window in the Pantheon Rome


Direct sunlight is that part of solar radiation which reaches the earth’s face without being scattered. It is a directed beam or a point source of light. Direct sunlight at noon can have illuminance as high as 120,000 lux (Compared to this moon light is <1 lux). Sunlight is a warm colour light, at noon, the colour-temperatures are about 5500°k, bluish-white or ‘cool colours’, and at sunset, these are about 2700-3000°k (degrees kelvin), are yellowish-white through red or called ‘warm colours’. This is similar to heated iron, like a horseshoe, it first glows red, but on further heating it turns to orange to yellow to white and, finally blue-white.


Colours at sunrise due to temperature differences

Daylight consists of direct sunlight and it’s reflected or diffused component. Daylight arrives or disappears when the Sun is approximately 18° below the horizon. (As the Earth takes 24hoursx60=1440 minutes to complete its orbit of approximately 360°, the 18° translates into 72 minutes period on equator and 23°N to S. For different locations and seasons the twilight time could vary). This is a twilight zone of early or late day lighting, when the Sun itself is not visible, as it is below the horizon. Twilight occurs due to the scattering of sunlight in the upper atmosphere, which in turn illuminates the lower atmosphere. This is a period when shadows are not yet present, and objects are silhouetted against gradually brightening sky. In extreme regions like the arctic where Sun may not dip below 18°, the twilight may be seen between evening to morning night period.



Three types of twilight within 18 degree –Wikipedia image by TWCarlson

The twilight effect is important for the stretched daylight period. It defines when street and other estate security lights can be switched on or off. It defines when certain outdoor activities like jogging, and exercises can be conducted. Interior areas of a building begin to receive illumination in the twilight period (near sunset or sunrise), allowing for switching on or off the artificial illumination.


Golden gate bridge at Twilight Wikipedia image by Brocken Inaglory

A twilight zone has been accepted as a prayer time in many religions. Egyptians wished to experience the first rays of the sun, for these obelisks like tall structures were erected near the temple entrance. The tapered top face of an obelisk was covered with shiny metal to glitter in the first sun rays of the day. Similarly Buddhist and Hindu temples used columns topped with shining metal sculptures like Dharma Chakra or Toran of metal pieces. A twilight zone is the time when cattle go out or come back from grazing, raising dust in the sky. This Go-Dhuli period is considered the most auspicious time for Hindus.



Twilight zone is cattle returning home after grazing with dust rising (GoDhuli time) -most auspicious period for Hindus India

Direct sunlight can warm up a surface depending on its angle and duration of exposure to the sun, surface colour and texture. Direct sunlight is the brightest illuminance and can be redirected through reflection to interior spaces by means, such as opaque reflectors, mirrors, tubes etc. It is used for generating electricity through solar panels. Direct sunlight casts a shadow, whereas diffused sunlight is scattered and arrives from all directions, so does not cast a distinct shadow. But, often enough diffused light arriving through highly directional openings, casts a dull shadow.


Skylight in Star Ferry pier Hong Kong Wikipedia image by VictoriaDFong


Day-lighting is used for illuminating a dully lit space or object by use reflective surfaces, appropriate spatial orientation or exposure, time scheduling or through design and placement of openings. The primary intention is to save fossil and other sources of energy, better recognition, reduce the glare, adjust the contrast and for highlighting.


Stratification of openings for Illumination and view II nd floor Children Library Bronx Library Center Wikipedia image by Julian A. Henderson

Daylight design takes into consideration the source and nature (intensity, colour) of the direct and diffused sunlight. One of the important holistic aspects of daylight design is the stratification of openings for illumination, and for view in and out. Stratification arises from the fact that daylight is arrives from the skies and grounds, both of which are strongly horizontal in effect. Daylight design is conditioned by the tasks to be handled, building form, siting, climate, architectural components and appendages, surface colours and textures in interiors, back up system of artificial illumination. At micro level design criteria include the opening size, shape, orientation, location, quality of glazing, opening treatments, position and orientation of interior components.




Post 550  by Gautam Shah



Dolly Johnson, personal cook to President Benjamin Harrison, in the small white house kitchen 1890

The human abode is focussed on the position of food preparation area. Oxford’s dictionary defines the focus, (originally a Latin word), as the hearth. The hearth, food preparation and mother, designate a home. Food preparation is just a slot in a time schedule with a casual occupation in space. Its task utilities, though are sited everywhere in the dwelling. Food preparation and related utilities are continuously shifted to exploit the environment, social needs, fuel management, built form, etc. as available within and without the precinct of a dwelling. Food consumption has been diversely connected to the food preparation area, mainly due to the discomfort of emissions from fuels of the hearth and secondarily the changing pattern of social relationships. As the dining moved away, the kitchen began to be neglected. The kitchen was likened to a dungeon, an un-owned or non-personal space, managed by a retinue of servants. The quality of food and related services failed to impress the guests. Compared to this, the participatory kitchens of crafts’ person or farmers were lively spaces.


Sudanese woman preparing traditional bread Kisra Wikipedia image by Mohamed Elfaith Hamadien

 Some Blog links on related topics:


FOOD PREPARATION SYSTEMS – II Kitchen and its place in the house

FOOD PREPARATION SYSTEMS – III Kitchen and evolution of its Facilities



FOOD PREPARATION SYSTEMS – VI -Kitchen Design by Fires

FOOD PREPARATION SYSTEMS – VII -Kitchen facilities and tasks



KITCHEN and its shifting position



Roasting, medieval illuminated manuscript (Tacuina santatis casanatensis 14th C.)



Post 549  by Gautam Shah



Intimacy is an individualized notion with primary concern for survival. Survival is a biological necessity. It is a defensive reaction where one tries to create a protective shield by distancing and sensorial indifference. It is also an offensive activity where to reduce the chances of physical (sexual, emotional) attraction one avoids person to person encounter, or tries to be part of a crowd. Manifestations of Intimacy are proximity, sensorial recognition and vulnerability, lack of protective cover for privacy and familiarity with people and objects. These are also important features of spatial experience. And, yet intimacy and space are not mutable.


TV host Jon Stewart being intimate by being closer to the guest

Intimacy is an attitude, mental conditioning or mental posture. It is a feeling of closeness or affinity with a person or an object. It relies on compatibility, sexual needs, glandular secretions, social acceptability etc. Meaning of intimacy varies from relationship to relationship, and within a given relationship. Intimacy is both the ability and the choice to be close, loving, and vulnerable. Intimacy could be one-way feeling that is without reciprocal feeling. One can feel close to a person who is long dead -an illusory presence, or through notional links (clothes, odours, recorded sounds, etc.). So intimacy is not always a function of physical proximity or spatial distancing.


‘Proposal’ by artist William -Adolphe Bouguereau 1825-1905

Intimacy can have two main forms: emotional intimacy and physical intimacy. There could be other forms of empathy like cultural, intellectual, spiritual, social affinity that are akin to intimacy in some conditions. Intimacy has more to do with rituals of connection. Strategic relationships developed to take advantage of someone could be very intimate, but it is make-believe closeness.


Crowding in trains Wikipedia image by author Jkamyiu

Intimacy and privacy, both are expressions of behaviour in a space, but former is not dependent on quality of space but later is substantially a product of space configurations. Privacy helps intimacy, but one can be intimate with a person or group of persons even without any apparent need for privacy. Intimacy is attitudinal positioning to control ingress, distraction and unwanted engagements by others.


Friendship and intimacy Wikipedia image by author Fernando de Sousa

Privacy and intimacy both are affected by the notion of distance. For privacy one resorts to physical distancing or barricading, but intimacy is a perception of interactions with other beings and objects. The distancing for privacy is in terms of space form, size and shape, intervening objects, physical reach and sensorial perceptibility. The perception of proximity for intimacy is factored by environmental factors, biological need, social requirements, communication, expression, psychological make-up, time duration and the relevance of objects and people.


‘Peasants playing cards by artist Hendrick Martensz Sorgh 1610-1670

A person projects privacy and intimacy concurrently, but in various proportions. The space facilitates different levels of physical closeness, isolation and insulation, however the mental needs ultimately define the degree of involvement. The culture defines the acceptable or inappropriate types of intimacies. A crowded stair, elevator, metro carriage, do not project an intimate environment. A handshake or hug nominally has no sexual connotation in many cultures. In some cultures, a veil is considered private enough to be retardant of intimacy.


Women in Shiraz, Wikipedia image by author Zoom Zoom from Beijing

Two persons or members of a group can talk in whispers and give out an impression of intimacy, in spite of the apparent distance between them. Conversely talk-discussions in high pitch could be used to present bonhomie, and thereby a non-intimate encounter. Politicians and celebrities talk in whispers to state things that need to be made public and talk loudly things that need not be public. A public orator changes the pitch from normal to very low to be intimate with the audience.



VERANDAHS and equivalent architectural forms Part – II

Post 548 by Gautam Shah



Verandahs are compared to Antaravedi, a land between two rivers -a Doab. A verandah is a territory between a public and a private domain. The duality of the verandah persists through its many different forms across climates and cultures. The usage varies from intensively participatory space, a shading device to a decorative appendage. Verandahs or similar architectural spaces have been placed on outer faces and also on inside face abutting the inner courtyards or chowks. These spatial entities have been ‘embryonic elements’ that have formed spaces and activities into a cohesive organization.




The built-form of rooms protects, but as an enclosed space it becomes sometimes oppressive enough, for need to transgress it. Walls are removed and roofs are punctured to connect to the outside or other spaces. The change is brought in or the space reaches out. The openings create a hierarchy of spatial zones, a remote or inner zone close to the wall, and a series of gradually varying environments of ‘internal openness’, and ‘external vulnerability. The spatial privacy and intimacy are passing and subjective, but not dependent on the spatial formations.




A verandah has had many architectural configurations. A lean-to like shade overtly attached to the shell of a building remains a casual expression for escape from the enclosed space. It is open on three sides as a transition space between interior and outdoor spaces. The low level of edge eaves frames the view. Such lean-to shades perambulate the house to provide shade and cover from the rains. It is a transition area between the public and private sections of the building, and circulatory space to access rooms that are often internally and intentionally unconnected, such as guest rooms, home office, food preparation area (Babarchi-khana), etc.





Pakistan Verandah

The verandah, of the mid-east architecture, the Iwan becomes the most important space for interactions, making the rest of the building a subdued refuge. Iwan or Liwan (Iwan with al prefix) relates to an old Persian word a-pad-an (appadana) standing for unprotected place (referring to the veranda-shaped structure open to the outside elements). A similar word in Sanskrit ‘apadana’ means ‘to arrive at‘. The Persian Apadana was a structure in as part of the palace buildings at Persepolis, with open verandas with columns on three sides. The columns and ceiling were replaced with a barrel vaulting, in Parthian and Sasanian architectures. This aywan of the post-Islamic architecture is a veranda, open on one face. A Riwaq is a longer or stretched out arcade or portico for transition, open on at least one side.



The traditional houses of mid-east regions have a multi-functional core space with distinctive spatial quality. The space offers controlled brightness and protection. It is more of a participatory space, and less for transition or circulation area. The space (till now) was for family engagements beyond the gender considerations. Such house forms with varied spatial arrangements, in various languages of the region, called as ‘tarma’, ‘riwaq’, ‘talar’, ‘ursi’, ‘hosch’ ‘sofa’, ‘eyvan’, engawa, ‘hayat, ‘lywan’, and ‘apadana’. These multi-functional core spaces are not outward transgressions but inward scoops incised from the shell of the built form. The front has been with and without columns, roof flat or vaulted, and the space height from single to multiple floors.


The typical Iraqi Tarma house is sited deep into the plot, with a largest possible courtyard in front of the Iwan space. The central space of the Tarma house is an atrium called as ‘hosch’ in Arabic. Tarma house courtyard has been often compared to A Roman atrium house (Also called Roman compliviatum). A Tarma house courtyard is open on all sides except for intentionally but separate buildings or neighbouring properties. A Roman atrium house, in comparison has a centrally located courtyard, well defined on all sides. Roman atrium side spaces can be compared to the Osari or Parsal spaces that abut a central courtyard called Chowk. Osari is a verandah or small Liwan like space with or without columns, on one or many sides of the courtyard. The Osari oriented to different directions and house elements (such as kitchen, entrance, water-storage, etc.) serves different purposes.




Post 547  by Gautam Shah


1 Akal Takht at Golden Temple Amritsar India Wikipedia image by Author Amarpreet.singh

1 Architectural finishes are coatings or paints that are more often than not, applied on the site, before and after the elements have been assembled as an architectural entity. These usually dry out at ambient temperatures -air drying, i.e., are non baking types. Architectural finishes, in comparison to industrial coatings are high pigment & extender build coatings. Substrates for architectural coatings are of THREE basic categories, 1. masonry, 2. wood, wood composites and fibrous surfaces 3. metal. In few instances architectural finishes are also applied in the industrial set-up, over systems, components and parts.

2 Colourful Homes at Burano Italy Venice Italy, Image attribution W. Lloyd MacKenzie via Flickr

2 Masonry structures are in the form of straight or inclined walls, columns, piers, abutments, and occasionally on roads, curbs and floors. A masonry structure could be made up of unitized blocks of compacted clay, stones, cement concrete or baked clay or bricks with their patterns of joints and joining materials. Masonry surfaces may have plasters of plain or rendered faces of clay, pozzolana, lime or cement, all strongly alkaline in nature.

3 Cement Wall Texture Wikipedia Image by Biswarup Ganguly

3 Masonry finishes, are of TWO basic classes: Exclusively protective coatings and Decorative finishes. Few commercial finishes provide both the qualities. Decorative finishes may be sub-classed as Interior and Exterior coatings, where the later category may offer substantial protection advantages.

6 Iron Oxide wash houses Pakenham st Shaftesbury square, S Belfast Wikipedia image Jeanne boleyn

4 Masonry surfaces cover very extensive area, and so water has been the ideal vehicle for formulation and also as an application solvent material. It is abundant and cheaply available and is non toxic. Water as a vehicle, however, has no binding characteristic, and for that reason many natural and synthetic adhesive type of gums and resins are used as binders. Where such substances are not dissoluble in water, various water-based emulsions are used. Latex paints or emulsion type plastic paints form the main section of such coatings for masonry finishes. On removal or evaporation of water, the film formed maybe substantially moisture or gas impermeable, or a permeable lattice in the form or water repellent coating.

5 Brighton Beach Melbourne Wikipedia image by Beau Wade

5 Voids over masonry surfaces are partially filled or levelled, causing a change in texture of the surface, when such coatings are loaded with pigments, extenders and fillers. In few instances this is unavoidable, but in many cases improvised `architectural’ or `rendered’ effects are intended. Fillers for such `rendered’ coatings include natural or treated mineral particles, quartz and silica sands, mica dust, glass and polymer beads, metal-dust, flakes, chips, or shavingsitaly_cinque_terre_mediterranean_europe_coast_tourism_italian_picturesque-843814.jpg!d

6 Some of the architectural coatings My Blog Links are >






7 Blue City Jodhpur India 28227257094829

7 Among the other masonry finishes, water proofing finishes constitute a major section. Such coatings are either `technical’ coats or part of multi purpose coatings. Technical coatings, impermeably seal the surface by covering all voids, pores and crevices; or cover the surface in the form of a lattice that is non wetting and so water repellent. In the former case the coatings are used where water vapour pressure is low and where a change in texture (due to filling up of voids ) is allowable, or desired. In the second case, texture properties of surfaces remain more or less intact, while the water repellence is provided by the ionic quality of the surface. Commercial water proofing coatings are based on Bitumen, epoxidized bitumen, PU coatings, silicone paints, and polymeric compounds.

8 Good film properties on masonry surfaces are achieved by using 100 % acrylics, or co-polymers of ethylene, or acrylic esters, emulsions of vinyl co-polymers. Chlorinated rubber with a suitable plasticizer, has a good alkali and atmospheric contaminant resistance. Long oil alkyd enamel with appropriate primer system work well for masonry surfaces.

4 Roof coating Wikipedia image by Waller42


9 Floor paints are used to improve the appearance, increase abrasion resistance, reduce moisture penetration and impart spillage proof qualities. Medium oil alkyds and moisture cured polyurethane, epoxy compounds, chlorinated rubber coatings are used. Road marking and curb coatings are very similar to floor paints except that in certain cases reflective or fluorescent pigments are used. Hospitals, operation theatres, pharmaceutical and electronic assembly plants, require joint less flooring and wall-finishes for bio-pathological reasons, or for dust less environment. Such finish systems are made from of chlorinated rubber, urethane or epoxy coatings. Wood or wood composite flooring in athletic and indoor sports area require a smooth, non skidding and spillage proof coating. Such coatings consist of melamine, urethane or epoxy materials.

9 Aircraft carrier HMS Ark Royal Paint Marked floor wikimedia image



Post 546  by Gautam Shah



Modern coating technology aims at two distinct targets, improvements in formulations and the technology of application. The formulations have been multipurpose as well as specific. Coating application methods primarily aim at high speed-pressure deposition of maximum proportion of solids, while minimizing the wastage due to over spray, drips etc. and economic use of VOCs (Volatile Organic Compounds). As a result, many combinations of formulation and application have been devised.

Ceramic coating over Metal as cutting edge Wikipedia image by Author SlonikkinolS

Coatings, traditionally were made of natural polymeric materials like starch, shellac, amber, cellulose, and rubbers. Man-made polymers have been known since 1832. Coatings of synthetic polymers provide better adherence and protection. Polymeric substances have been used in paints and other means of covering such as extrusion and dispersion. Such coverings (e.g. Teflon coating, PTFE, PFA) have heavier films than paints. Polymer covering materials replaced tin, chrome and cadmium plating in many instances. Polymer coating materials include alkyds, vinyls, acrylics, epoxies and polyurethane.


Non-polymeric coatings or coverings are created through following basic routes.

1 Galvanic deposition: A metallic compound migrates from a high potential cathode, to the object, that is an anode. The migration is at molecular level with the formation of an alloy or like substance at the receiving end.

2 Oxidation: An oxygen donor fluid or substance is encouraged or facilitated to migrate and form an oxide coating to protect the substrate.

3 Melt Deposition: Metal, Ceramic or Polymeric substances in the form of particles, flakes, fine grains or foils are sprayed or fixed to the substrate, and are melted or fluidized with the help of heat (thermic, sonar, radiation, friction), before, during or after the deposition. The fluidized material forms not only a coating but integrates itself into the substrate.

Metalized polymer yarn Wikipedia image by Author rexess


These techniques of material application are used in commercial processes known as:

  • Electrostatic coating
  • Electrophoretic Coatings
  • Anodization
  • Electrolysis of organic substances
  • Diffusion Coating
  • Electro-deposition
  • Spark hardening
  • Conversion and Conversion – diffusion coating
  • Chemical Vapour Deposition
  • Electro-less and electrolytic metal deposition
  • Welding as surface coating
  • Printing as coating
  • Air and airless spraying
  • Flame spraying
  • Metal sprayed, polymer, impregnated coatings
  • Detonation coating
  • Arc plasma spraying
  • Electric arc spraying
  • Electric harmonic spraying
  • Vacuum metalization of plastics and metals
  • Sputter deposition
  • Ion plating
  • Ion implantation
  • Microwave radiometry coatings


Electrostatic process based printing-coating Wikipedia image by Author Guruleninn

Air electrostatic processes employ air forces to atomize the liquid material and then charge and deposit these particles using electrostatic forces. Articles to be coated are introduced to a space or chamber which provides negative charged environment. The atomized coating droplet on collision with ionized air picks up the negative charge and as result is attracted to the grounded article (to be coated). In another method the spray gun nozzle has an attachment to charge the coating droplets. In such processes, because of attraction there is no over spray wastage and deposition is very secure. Such processes are readily applicable for coating with suitable electrical properties and for articles that are conductive (metals).

Road Coatings Author English: Cpl. Ryan R. Jackson

For architectural coatings, polymeric formulations rule the scene. As majority of such finishes are based on emulsification with water, requiring negligible-amounts of volatile organic solvents. For wood and metals, modified alkyds that need organic solvents are being replaced with solvent-less formulations like powder-coatings. The products manufacturing at plant level, however are adopting metalizing, surface alloying, ceramic coatings, sputter deposition, Ion plating and Ion implantation sputtering technologies.




Post 545 –by Gautam Shah



Stairs and escalators are stepped and inclined-vertical transfer systems. Both provide uninterrupted transfer, unlike the modulated transfer by elevators. Traffic on stairs and escalators is restricted by the width of passage whereas the same on elevators is limited by the module size and its speed. Use of stairs requires some orthopaedic proficiency and cautious posturing, but automated escalators allow freedom to see around during the passage. Some flight of stairs can be used for accent and descent, but escalators require different sets. Though reverse escalator for descent may not be provided, as physically it is not very strenuous to climb down.

Streets of Cusco, Peru Wikipedia image by Author Rod Waddington from Kergunyah, Australia


All movements are essentially directional. A designated unidirectional system like an escalator is more efficient than a mixed movement system like a stair. This factor, however, is relevant for stairs with low to moderate traffic. There are several other transfer systems, such garbage chutes, emergency evacuation tubes, trunks or ramps, and fire-mans’ poles, where movement is unidirectional and generally downwards. The gravity accelerates the down-movement, and inclination retards the rate of passage.

Staircase and escalators at Cabot Circus shopping centre, Bristol, England Wikipedia image by Author Arpingstone

Stairs and escalators are point to point passageways, as there is no mid-way interference, except at landings. Mid-way disturbance occurs in comparatively flatter and very wide stairs over the mountain sides. Here, for ascent or descent, people cross the steps diagonally to increase the ‘tread-depth’ of the steps. Stairs generally have a pitch higher than ramps. Stairs are safer than ramps provided the person is fully mobile and orthopaedically fit, but to ascend or descend stairs are not as easy as the ramps. A ramp can have gradually variable pitch, but a stair has to have a one continuous grade of pitch.

The Grand Staircase of the RMS Olympic Wikipedia image


The inclination of steps is defined by the proportion tread versus riser of the steps. This could vary for stairs used for different purposes, ranging from steep ladders to flatter ramps like foot-ways. The dimensions of tread and riser are proportional and can be plotted on a hyperbola. Certain formulas also provide such proportions: 2T + R = 650 to 680 mm or R x T = 43000 to 45000. For steeper pitch the additional effort required to work against the gravity reduces the efficiency.

High pitch steps of ChetSingh Ghat Benaras India Wikipedia image by Author Patrick Barry from san francisco, ca, USA


Stairs have a pitch of not less than 17.30° (5:16), and of not more than of 48.30° (9:8). Below these limits it becomes a ramp or foot-way, and above it a ladder. A ladder is not a comfortable utility. Step-ladders are lower in pitch, less than 75° and require flat treads. Risers may be open or closed, for toe accommodation and handrails may or may not be provided. In the ladders’ class of stairs, some are easier to climb than others. Ladders are used for fire escapes, boiler rooms, fly galleries, attics, decks, etc. Rung ladders are pitched more steeply, above 75°, and have extremely narrow treads or round rungs to accommodate the foot. In certain cases, the space to accommodate the knee between steps may be necessary. Rung ladders usually do not require additional handrails as the side members of the ladder can be used for holding grips. Rung ladders are often caged for safety, though such cages are more useful for ascent then for descent. It is safer to climb down facing the ladder. Swimming pools, water tanks, and sewers have rung ladders. Manhole steps are very narrow in widths, but the width is otherwise compensated by its staggered placement. The same holds true, for climbers for bunk beds, whether in railways, buses, barracks or homes.


Minimum width required for low intensity unidirectional traffic is 600 mm, however most standards specify 900 as minimum width for escape in a hazardous situation. A two-way lane stair should be at least 11200 mm. Sufficient width space for movement is required at torso level, otherwise at feet level a minimum width of 250 mm is required. Where same step is to be used for placing either one of the feet, both, the step and passage widths of minimum width of 500 mm are necessary. Stairs less than 500 mm width are generally emergency stairs rarely to be used, or service stairs to be used by experienced persons. For single lane traffic 750 mm width is an accepted standard. Most of the building bylaws allow minimum 900 mm widths for private buildings. For public buildings a stair width of 1200 mm to 1500 mm is recommended. For pedestrian over bridges and other public thoroughfares, a stair width of 2400 is recommended. On public thoroughfares where traffic is totally segregated or is only one directional, the minimum stair width could be 1800 mm.

Tsarist soldiers march down the “Odessa Steps” from the Goskino film Battleship Potemkin (1925)

Same (filmed as above) Potemkin Stairs giant stairway in Odessa, Ukraine in 1990 Wikipedia image by Author Dezidor

Many stepping arrangements are used for emergency and special purposes. Simplest is a knotted rope or a rope ladder secured to a wall or column. In many countries older buildings were required to confirm to new bylaws, open iron stairways on the building’s exterior were placed. Open iron stairs, though are rendered useless by smoke from windows, so must be placed against a blank wall. One of the best fire escape stairs is a fully enclosed stairway in the building itself or in an adjoining tower. Uncoated or unprotected steel is highly hazardous during a fire as it expands and deforms the stairway. Wood though combustible catches fire slowly, and allows more escape time compared to an unprotected steel stair.





Post 544  by Gautam Shah


Buildings are restored to retain and perpetuate select identities. The selection is a subjective process of a person, society or the political power (including invader or conqueror). The concept of restoration is comparatively easy as the retained identities seem to provide a link between the past and the present, whereas things that are ignored or removed, make the exercise easier, simpler and justifiable. The select identities are like values, utilitarian aspects, sensorial qualities, materials, technology, architectural character, spatial qualities, style, patterns, scale or proportions, antiquity, social-political-religious confirmation.

An early photograph of Stonehenge taken July 1877 Wikipedia image by Author Philip Rupert Acott

Pic from same position in 2008 showing the extent of reconstruction Wikipedia image by Author Mavratti

Buildings as affected by age, environment and human use become increasingly inefficient, irrelevant and unsafe. The environmental processes continue to change the fabric of the buildings. The human use, miss use and non-use, all reflects in the decline of the building. To terminate or arrest the affectations, several processes of change are required. Externally, the purposes with which a building was erected need a live sponsorship and continued participation of the society. The buildings’ location needs corroboration from its surrounding, which can be had through macro planning or re-validation of the functions. Internally a building is a visit-able entity or just relic, for both cases it should be stable and safe.

Partly-restored windows facing Pitched Stone Court, Raglan Castle in Monmouthshire Wikipedia image by Author Andy F

A restoration, cannot revert a building to its original condition. As there is no original condition of a building. What we perceive to day is an entwined mass of effects of age, environment and human use. Changes occur in time, and spatially across the fabric of the building. Buildings are nominally as well as intentionally altered, but these changes are never recorded. The evidence of previous conditions in absence of records is largely conjectural. A true restoration must faithfully use the original materials and technologies which however are unlikely to be available. The building loses its site related relevance and time related functionality over a period of time. One, cannot regress a building to a past state in isolation of its referential conditions.

Marcellus theater Rome

Theater of Marcellus Rome backside reconstruction

Medieval builders treated the works of antiquity as something to be extended. They knew that abandoning a well sited and a large sized building is a wastage of time. A large new building would take several generations, political stability and long period free of catastrophes and disasters. Restoration meant resurrecting a building in the shortest possible time, with an image or style of the time. Yet during resurrective restoration, there were several ‘corrections’, to suit the socio-political-financial conditions. Such a complex entity cannot have a particular or ‘original character’.

Serbian monastery Gracanica Wikipedia image by Author Bujar I Gashi

From ancient times to first part of present century, restorations have always followed the sponsor’s wishes and restorer’s wisdom. Restorations have meant all types of changes, such as renovations, alterations, reformations, additions, and extensions, but rarely the ‘reinstatement of a previous condition’. ‘Restorations’ have been carried out by masters such as the professional artists, sculptors and builders and street level roving crafts-persons. The nature of ‘change’ interventions depended on the skills of the master. Such changes were primarily intended to upgrade the building to a better condition. It also meant ‘improvising or adapting a style or confirming to a contemporary taste’. Restorative changes have been carried out by experts to brand their capacity rather then any respect for the past. Restorers like Michelangelo, saw a building as a raw material and opportunity to organize it. Classical structures during Romanesque and Renaissance periods were as regarded pieces of admirable antiquity. Yet these were restored by retaining, enhancing and adding the perceived values, but ‘without any concern for the process or investigations’.

1 Ishtar-gate-بوابة-عشتار


Reconstruction of Tito’s Palace in Mostar. Part of film depicting several buildings and structures that have been damaged during the Bosnian War, wikipedia image

A restoration destroys something of the original character. It is irretrievably lost. The character of the building gets lost with too many restorations. Restorations without harming the substrate or basic fabric preserve them in their original condition. But, that does not mean a restoration allows one to mount a skin or a make-believe screen, to camouflage the original. Conservation is very restrictive process, but restoration could be conservative and preserving in nature.

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