Post 437 ⇒   by Gautam Shah 


Coatings are applied as Single or Multi coat systems. The choice depends on several factors, such as:

  • Economics
  • Opportunity offered by technology
  • Emergency or routine application
  • Site accessibility in terms of location, weather, and tools available
  • First or virgin application or a re-coating job
  • Thickness of film required

One-coat system has inherent efficiency, as it requires lesser amounts of material, solvents, curing energy, and takes less time for application. However, in one-coat systems, the coating is required to provide adhesion with the substrate, necessary film build or thickness, and also fully cover up the surface. Single coat systems have to be fail-proof, as there are no remedial opportunities. Performances of single-coat system, depends very closely on the type of (readily available) substrate. If the substrates are large then one has to select different coating system for different substrates or go for ‘All purpose system’.

Painting Hull of a Ship

Multi-coat systems consist of two, three or more layers of applications, such as, Priming-coat (filler or sealing coats), Undercoat (sub coat or intermediate coats) and Finish-coat (top coat or surface coat) These multiple layers are designed to perform specific functions and also take care of any shortcomings of the preceding coats. In multi-coat systems, different coats can be applied at different times and locations, as required. Primer-coat can be a factory application, Intermediate-coat could be part of the installation procedure, while, the Final coat could be applied with other finish systems, just prior to usage. Multi-coat systems have an advantage over many high-build or one coat systems, in that the final coat can be of the same type for different substrates or undercoats. In multi-coat systems, the sub layers could be of economic materials, as it is the final layer that is exposed to the atmosphere, and provides the tangible surface finish.

Single coat systems are applied to save time and cost of application. Very large walls, giant structures (Eiffel tower, pylons, or Bridges), Road side barricades, Road marking signs, Ships, Marine structures, are some of the entities that must be re-coated in one effort. These are re-application systems, so the substrates have some form of existing coating. The condition could be, severely weathered surface, fatigued or peeled original coating, presence of salts and other reaction products, deposits of dust, grime, etc. Some of these extraneous or by-product matters cannot be removed easily or completely from where they exist (height, nooks, corners, etc.). Such structures are exposed to vagaries of weather, such as very high or low surface temperature, condensation, rains, humidity, high winds and environmental pollution. Where the technology of stripping of aged coatings is available, it may not work for such an extensive surface, including undersides.

Graffiti – Vandalism

Multi-coat systems are as varied as their modes of applications are. Multi-coat systems have a prime or primer coat, followed by one or more finishing coats. Multi-coat systems need an interim ‘rest’ or through drying period, before next coat can be applied. Finishing coats are often designed as ‘removable or stripping system’ by mechanical grinding or chemical scrubbing, or both. Primer coats are specifically designed for the surface to be applied, such as wood, metal or masonry. Multi-coat systems are applied by exclusively by brushing, roller, spraying, dipping, or in combinations of it. With brush application final coating is by vertical strokes.

Art work Painting

Multi coat system




Post 436 ⇒   by Gautam Shah 


A product is born through improvisations, and rarely through sudden ‘eureka discovery. During the last few centuries, a series of products has been ‘improvised’ upon the existing ones. Many of these products were very successful ones in the market, and to remain steps ahead of competitors had to be continuously upgraded. One needs to be aware of how others are innovating with radical technologies, styles, additional functional provisions, compactness, energy efficiencies, superior handling, ease of repair and servicing. And one had to absorb these and deliver it fast.

Nintendo accessory with four buttons connected to the bottom of an opened gaming handheld.

One of the Technics of Design or the Design Process is Redesign or Re-engineering. Most products, however claimed to be original, are only improved versions of some existing thing or a Redesign. This is a well accepted design process for products’ development. It has perhaps, a little less relevance in design processes of unique or first ever systems, such as Civil structures and Architectural entities.

Electric Stove

6057016377_923f46a962_zManufacturers need to design new products and launch them before their competitors do. Redesign or Re-engineering is used for product development for Automobiles, `white goods’, office equipments, etc. For this markets are continuously surveyed to find out the features that make certain products leaders in the market. An attempt is made to absorb and improvise such features. As one is working with a successful subsystem, the chances of its failure are less. Redesign generates a product in its new Avatar.

Volkswagen Beetle

Redesign addresses to deficiencies of aging technologies, fast changing tastes and varying operative conditions of products. It gives very specific clues which new features are accepted, and which are the emergent styles and technologies. It also allows faster incorporation of new technologies, as offered by inventors. New products are launched with minimum changes to existing tools and plant. Workers only need to upgrade their skills, and new employees or new training schedules are not required. The improvised product has slight familiarity with the existing range, and as a result comfort of acceptance is high.

White goods fast changing market

Redesign practitioners operate with notions that:

● A whole system is divisible into subsystems, each of which can be improvised.

● These subsystems can be improved in-house, but technologically better solutions can be developed by others, so identify them and collaborate to resource such emergent solutions.

● It is more efficient to redesign or re-engineer a known system, then go into basic research to discover a new entity.

● A product of redesign process has fewer chances of failure, because one is improvising upon a working system.

● Transfer or absorption of new Technologies is very fast.

MS Arc Mouse

Redesign processes have few negative features. Redesign processes require many field surveys for identification of a market leader product. The field data is often so enormous and with minor or rare variants that it may require complex statistical processing. Very often feedback from consumers is subjective in nature. There is a distinct danger for the design leader/ team to get entangled in the data collection and interpretation work at the cost of essential design clarity and creativity. Redesigned products have to be very careful about infringing intellectual property rights of others. It is also extremely difficult to secure patents, copyrights, etc. for such fast developing line of products.

Organizations, that deal in very competitive markets, prefer redesign processes as it allows them to continuously update their product with minimum of risks.

Philips Tape Deck

Japan perfected the process and achieved distinctive product design solutions in early 1960s. Sony music system Walkman has evolved from such efforts. At that point of time taped music systems were very bulky and weighed very heavy. To enjoy the hi-fi sound quality outdoors it had large sized twin speakers (these were often called Ghetto or Beachfront blasters). A new Walkman delivered the sound directly to the ears, through earplugs as speakers. The tape decks had open spool type tapes, but the Walkman had smaller cassette type tape system. The compact unit now worked on micro motors operated by smaller batteries (lasting eight instead of two hours). It was a redesigned entity that became a very innovative product.




This is not an exhaustive list






































CORRIDORS and PASSAGES Transfer Systems in Buildings (Part – III ) Passages

STAGE CURTAINS Part 1 Performance Spaces






COLOURS -Perception and Expression






Post 434 ⇒   by Gautam Shah 


There are many ways Design is conducted. The Technique of Design or the Design Process determines the nature of output. There are obvious factors that are common to all design processes such as Nascent effort or routine application, Human and other resources available, Technology involved in design, Presentation tools and methods, Scale of detail, Execution methodology and Operations systems.


Some of the important Design processes are: 1 Holistic approach, 2 Component approach, 3 Redesign or Re-engineering and 4 Concurrent engineering or Simultaneous design.

Air Force Academy Chapel Colorado springs by SOM of USA

COMPONENT APPROACH is one of the oldest approaches used for designing slightly complex entities. Here an entity is perceived, as if composed of several components or subsystems, each of which are optional or replaceable. The components or subsystems are universal as are relevant for other conditions.

Four stroke single cylinder engine components

The design is a continuum, and one improvises it by changing a component its method of joining, placement or context. Component approach (parts to the whole) provides systems that are reliable, and well connected to the existing one. Where situations demand a radically different or a novel solution, parts to the whole design approach are often inadequate.

Ghetto-blaster family of Audio tape decks -replaced by Sony’s Walkman

The component approach requires one to have a complete overview of the functions the parts and the objects are to serve. This also translates into understanding of relationships between various components. Components are mutually related in time and space, and this makes it easier to devise a replacement. Replacement components are superior in form, function and their association with other subsystems. Replacements modify a system forming a new system.

Khajuraho Kandariya Mahadev Indian Temple Components

Components with high degree of mutual connectivity are less affected from conditions beyond their boundaries. Component approach creates systems with some regimen where subsystems have predictable dependency and yet are replaceable.Component approach systems’ are fairly fail-safe because individual segments, parts, or components are continuously and concurrently being evolved in the society.

616px-Republic_F-105B_with_avionics_layout_060831-F-1234S-046Modern day automobiles, computers are examples of Component approach to design. For ages large number of buildings are being created through Component approach. ‘Monuments’ and highly stylized architectural works intentionally and intensively negate the component approach for the sake of Holistic image.




Post 433 — by Gautam Shah


Comfort of users in an interior environment depends on:

1. Temperature of Environment and our Body

2. Level of Humidity,

3. Air velocity,

4. Quality of Air.


TEMPERATURE OF ENVIRONMENT AND OUR BODY need to reach some equilibrium. In an Interior space, environmental temperature is modulated by the built form and its amenities. Direct solar radiation heats up various objects, depending on their thermal capacity, conductivity, colour, texture, etc. Heated objects radiate this heat, as long wave radiation, back into space after the main source has ceased its input. Delayed heat releases create very complex patterns of heat gain. A temperature profile in any space is rarely even and this causes different gradients and convective air movements. Such air movements affect the rate of evaporation and the level of humidity in a space, rate of ventilation, and quality of air.


All sides covered Winter beds

Temperature is the major determinant for comfort level. Air temperature determines the rate at which our body will exchange heat with the environment. Rate of heat exchange affects the metabolic activity of the body and as a result its work capacity, fatigue and recovery schedules. In a temperature range that is acutely different from the acclimatized one, our body has to work harder to adopt to the situation.

Street Sanaa Yemen

LEVEL OF HUMIDITY is the amount of vapour held by air at a particular temperature. With a rise in temperature, the expanded air accommodates more humidity, whereas a drop in temperature condenses the humidity. Proportion of humidity at any given temperature affects the rate of evaporation and the heat exchange of the body through perspiration. Excessive loss of humidity from body, and high proportion of humidity in air, both affect our sense of well being and comfort.

Hot-Humid climate Forest Rest House Theppakadu S India

In hot and humid climate high level of humidity does not allow adequate heat dissipation through evaporation of the perspiration. As a result body temperature increases and it has to resort to other methods of heat dissipation. In hot arid climates the low level of humidity causes rapid evaporation. Body cannot cope up with such rapid loss of moisture, as it has limited amounts of water available within it. In cold arid climates the body has no excessive amounts of heat requiring dissipation through high perspiration, however, the low level of humidity removes even the moisture that helps the skin to remain soft and supple. In cold humid climates even minute perspiration does not evaporate readily, and in excessively cold climates it may cause a frost bite.

Cracks and crevices offer passive ventilation

Air with high percentage of humidity is comparatively deficient in oxygen and may cause problems to people with TB or asthma. Low level of humidity removes the moisture from the nostril, reducing its filtering capacity to keep out the airborne pollutants.

AIR VELOCITY is caused by temperatures and pressures differences across locations, within connected spaces. Air can also become mobile due to fans or such air circulating devices. Air velocities go below 0.15 m/s, and most people complain of stuffiness, in spite of all other parameters of comfort being satisfactory. Air velocities above 1.5 m/s, are annoying, such as papers being blown out or dust stirred up. People may tolerate such extreme (high and low) air velocities under very hot-humid and cold-dry conditions or for the sake of body thermal management.

Children and aged persons have poor body Temperature control mechanism and so need to be protected

Draughts are low velocity air movements, which occur due to temperature and air pressure thresholds near cracks and such leakage points in enclosed spaces. In enclosed spaces, draughts are not always perceptible, as they do not cause any sensation of pressure on skin. Draughts, however, help in convective heat exchange, evaporation and dilution of pollutants in air. Draughts cause localized cooling or heating of sensitive organs of our body. Such sensation on feet is a common experience in trains, buses, sofas, undersides of office tables, etc. Children and aged people with deficient blood circulation and body temperature regulatory mechanisms, are readily affected by such currents.


Breeze is a low to medium velocity air movement, which affect only local areas. The breeze does not let air borne particulate matter to settle down. Breeze causes effective pressure on skin, with immediate and very perceptible skin sensation, which can be avoided by appropriate screening and deflection.

Thar Desert House with twigs -gaps crevices offer passive ventilation

Winds are very high velocity movements of air. Winds affect large regions, and few interior spaces. Winds raise particulate matter in the air, cause rapid change in level of humidity and cause discomfort due to high pressure sensation on the skin. In hot and cold both types of climates people often close all the openings to reduce the air movements and thereby control the convective heat gain or loss.

Trans Sahara Desert House Minimum openings

Turbulent air velocity is less comfortable than a laminar air velocity. Turbulent air movement achieves a better mix of air, whereas laminar helps in greater displacement of air mass. This is the reason why in hot arid climates small size opening is used to create turbulence or a viscous flow, and in hot humid climates body level openings help a laminar flow to displace the humidity.

QUALITY OF AIR represents the health supporting conditions of interior spaces. Pollution of internal air occurs due to occupation of space by people, plants and pets (exhalation, body odours, excretion product odours, food preparations), gadgets and equipments, building and furnishing materials. The quality of air is usually determined by people’s sensation to various odours present in the air. But certain harmful pollutants like carbon dioxide and radon cannot be perceived by people at high concentrations.

Quality of air is determined in two ways. There are absolute standards that provide for ideal conditions for comfort and bio survival. Relative standards provide ways for determining the qualitative difference between out door air and indoor air. Quality of outside air is generally superior because an infinite space and high speed winds are available for dilution to occur. Quality of internal air can be improved by diluting the proportion of pollutants in air, by replacing part of the fouled air with comparatively cleaner air, or by various mechanical and chemical scrubbers.

Particulate matter is a major source of air pollution, which mainly but not necessarily, originates outside and penetrates inside through various cracks and openings. Particulate can be dust, fumes, mist or biogenic matter. Particles of diameters greater than about 75 microns settle out rapidly and are termed grit. Particles of smaller than 50 microns may remain suspended and constitute aerosols. An aerosol is a liquid or solid particle which is in a quasi stable suspension in air. Very fine aerosols may remain suspended for weeks, whereas larger aerosols may get deposited in minutes. The deposition of very small particles (2 microns) is influenced by temperature gradient (through convective currents). The effect on health due to airborne particulate matter of biogenic origin such as fungi, moulds, bacteria, viruses, pollens are well known.

Kitchen major zone for Air contamination

In modern artificially controlled environment buildings are well designed and sealed to eliminate waste leakages. Such spaces function well so far as environmental systems operate. Pollutants arising from building materials, aerosols settling down, degradation of biotic materials, evaporation of condensed moisture from air handling plants, etc. continue to be added to the internal environment but at night time, on off days and when there are power breakdowns, there is no casual ventilation.





Post 432 ⇒   by Gautam Shah 


There are basic TWO sets of Arts. Portable arts, comprise of objects or artefacts. These usually remain in protected environments. Fixed arts are built-forms, wall murals and architectural embellishments, all could be part of exterior and interior environments, but always affected by the behaviour of the environments.

Venus of Brassempouy (Lady with the hood) fragmentary ivory figurine from the Upper Palaeolithic

Bronze bead necklace, Bronze age, Penne, France

Portable arts consist of wide variety of object forms and material combinations. Compared to the fixed Arts the objects are smaller in size. The portable objects show all, the surface treatments, coating application and embellishments. The objects of this category show greater integration of all the three interventions and greater detail or involvement. Large number and wide variety of objects have been preserved and recovered from regions where Fixed Arts entities have not survived. Portable arts’ objects are smaller and one person hobby or a family craft creation. These are forms of personal experimentation or creative satiation, and to a very minor extent for business production.

Pigments and engraved pieces of ochre

A petroglyphic Saharan rock carving from southern Algeria depicting an antelope or gazelle.

Fixed Arts entities that have survived are show painting, scrapping, etching and daubing methods of surface treatments. On the other hand the surviving built-forms, if can be considered the art-form, represent technological milestones of material handling, supporting and construction planning. Fixed arts are large scale or important societal activities. These involved entire community by way of voluntary participation or forced labour. The involvement of the community was for seasonal or occasional rituals. The leader, conductor or priest of the ritual and the team were the select few experts who initiated and updated the entities over and over again. Such art-forms indicate occupation or interventions of several generations, as much as for more than 300 years.

Bradshaw rock paintings

Poulnabrone Dolmen in County Clare, Ireland

Portable Art objects are incidental that is the availability, shape, size, colours, texture, etc. define the range of treatments. Many times the purpose it will serve evolves during the process of treatments. Such objects show material combinations. Exploiting basic tools by changing their forms and usage, many different finishes were achieved. Material processes like heating, singeing, sintering, baking, beating, shaping, cutting, chopping, grinding, drilling, etc., were also used in farming and cooking. It was one seamless manner of learning. The objects were natural and self-combined or processed. These materials were stones, precious stones, metal nodules, mineral and other colourants, woods, grasses, twigs, hides, leathers, skins, furs, hairs, shells, teeth, horns, bones, clay objects, baked clay ceramics, seeds, fruits, etc. The objects formed were totems, body adornments, tools, implements, ritual and burial objects, cooking utilities, toys for children, amenities and dwelling embellishments. These were exchanged, gifted to others or offered in rituals. The objects began to have consistent expressions that were gestural. The varied metaphors, passing from one generation to other, ultimately became abstract. Coins, plaques, seals, etc. represent multiple conversions of expressions like a language.

Ggantija temples, Gozo. Some of the world’s oldest free-standing structures.

Fixed Art objects like built-forms, though functional utilities were built through community efforts, or initiated for political purposes. These entities were irrigation facilities, forest clearance, dykes, bridges, walks or passages, drinking water resources, community surround structures, security amenities and storage arrangements. These were not ‘decorative arts’ but symbolized technological innovations. Some like burial stones and dolmen had items of personalization.

Bhimbetaka India Cave paintings

Fixed Arts objects like wall arts show skills of surface preparation, rendering or painting and surface finishing. These creations also show art of surface preparation by way of grinding, etching, daubing, engraving and colourant application. Wall-arts exist in odd narrow corners, at very high elevations, tall ceilings, day time dark corners and in nearly inaccessible places. The effort must have required support structures, bridges, scaffolds, illumination and ancillary works to protect the creations from moisture.




Post 431 ⇒   by Gautam Shah 


Translucency of a fabric for has been an important factor how curtains sensorially affect us. In ancient times when heavier tapestries including rugs were hung on openings, little light seeping through the weaving or worn out gaps was very much pleasing experience. Light through the woven material gets refracted by the surrounding fibrous texture of threads at the gap point. It not only diffused the glare of outdoor light but created a warm glow due to the unbleached warp yarn.

Nominally our experience tells us that heavy fabrics are more opaque, and light weave fabrics are translucent. Though there are many exceptions to these, due to the nature of fiber, its post spinning treatments, use of colourants and nature of the weave. For the favour of anyone (heavy-opaque or light-translucency) the others can be redefined. Fabrics are lighter, because the fibres are naturally thin, can be spun to a very fine count, filaments or long staples in nature, and woven with a single weave or similar techniques. Fabrics or fibres dyed to lighter shades seem less heavy. Fabrics with finer warp yarn tend to be tightly woven rendering it to be opaque.

The substantive determinants for perceptual and actual transparency or translucency of a curtain material depends on Treatments over a fabric, mode of hanging and pleating, presence or absence of a liner-layer and the secondary treatments over the opening itself.

The illumination conditions of the interior space, and the viewing position in the interior or exterior location, substantially affect the perception of transparency. A bright exterior or one that allows greater proportion of ‘sky component reflection’ (the reflected light from the sky) such as clear sky days, openings on sea coast, very vast open grounds, on the upper level windows in tall buildings, and very bright or highly a reflective frontage of urban streets, all contribute to the brightness over the windows’ plane (an exterior side). A bright exterior side and a glare-less interior, both add to the translucency. A curtain fabric shows the glow of exterior daylight when the interior glare is less dominant. Such conditions also arise when areas besides the curtain are not highly illuminated, or furnished in lighter shades. A direct sunlight exposure of the window makes the curtain seem opaque (at least from outside) where as a deep shade or awning makes a curtain ‘see-through’ entity.

The perception of transparency is governed by the construction of the curtain, such as design and density of pleats, presence or absence of back-layering, and the direction of the weave. The natural way of fabric orientation for curtain is the warp forming the vertical orientation (and the weft the horizontal position). A curtaining system, called Railroading, places the fabric, with weft forming the vertical orientation (and warp the horizontal position), which makes the fabrics seem more opaque. Curtains are also formed with multiple fabrics of synchronized colours or textures. The mid sections are formed with lighter (or white) fabric, allowing more light, feeling of lightness and view-through facility.

Fabrics of Filament yarn (very long fibres) such as of silk and synthetics and naturally very thin and uniform section, allowing lighter density weaving. But filament yarns of synthetics provide fabrics with a glossy finish, which takes away the ‘glow from back’ effect. Compared to these yarns of natural staple fibres of cotton, jute, wool, etc. and Rayons, have variable section and micro fibres jutting out, after spinning. Such yarns create weaves with many small gaps, and the micro fibres diffract the light.

Sound absorbent clear curtains

Silks have been the first choice for sheer curtains due to fineness and natural ‘fall’ it offers. Sheer curtains are known as privacy curtains. Some of the best sheer fabrics are of pure silk, but most of the commercial materials are made of synthetic filament yarn (long length fibres). Very fine count cotton yarn fabrics such as lawn, cambric, chintz, voile, Malmal, muslin, etc. are also translucent, but have a tendency to creasing, and the quality of ‘fall’ is not natural.

curtain sheer

Glow of Comfort curtain

Fabrics in lattice or nett forms are created through weaving, knitting, netting, crochet and such other constructions. Embroidered fabrics were used in Dutch and Swiss dwellings. Sheer fabrics flourish with their pleats and resultant folds, whereas the embroidered constructions brandish their self-patterns. Such constructions are very pliable and semi-transparent like a sheer fabric curtain.

Nett woven fabrics of cotton and synthetic materials are soft and of substantial to flimsy body. It is nett density (or lightness) and the pleat formations that add to its hazy see-through charm. Nett patterns are created by singeing fusible weft or sections of fabric, or by selectively pulling out the weft yarns.

See-through curtains nominally form the first layer in multiple curtains’ system. Such curtains allow a fuzzy view of outsides during day time, but at night may require an opaque topping of a curtain. Such fabrics or constructions must not be used with a lining fabric, to maintain the translucency. Similarly such curtains not embellished and embroidered for patterns. Such extra work increases the weight of the fabric at the cost of graceful fall. These types of curtains are commonly heavily pleated or hung as a plain panel (such as a roller or horizontally folding curtain) and so the total quantity of cloth required for must be pre-considered.

Victor Mottez zeuxis -use of sheer curtain