Post 577 by Gautam Shah


Egg white, yolk and plant gums have been part of our life since prehistoric times, as thickening and emulsifying agents. Plant gums, like ‘Gum Arabic’ was used as thickening agent (and as a binder) for body paints, pottery colours and as a food emulsifier. Egg yolks and oil do not mix well but slowly whisking it can create a non separating, stable emulsion. This was technique was also used for forming colour pastes for wall paintings. The colours mixed into an emulsion did not drip or run during application. The egg offered substrate binding properties, whereas the oil helped protect the surface.


Churning cream to make Butter > Wikipedia image by Adam Engelhart from San Fransisco, California, USA 

An emulsion is a mixture of two or more immiscible (that would not normally mix) liquids. It contains very small particles (droplets of microscopic or ultra-microscopic size) of one liquid distributed throughout the other. Chemically, these are colloids with liquids as both phases. In an oil-in-water emulsion, such as butter or margarine, the continuous phase is water and the dispersed phase is oil. Opposite to this, the water-in-oil emulsions, the oil is in continuous phase and water is dispersed into it. Butter and margarine, are examples of water-in-oil emulsions. Mayonnaise is an oil-in-water emulsion, stabilized with lecithin obtained from egg yolk. A mix of oil and water when agitated, forms a temporary emulsion, one where liquids separate immediately. But traditionally emulsifiers like gum Arabic, egg yolk, were used to stop the coalescence of oils droplets.


Mayonnaise whisking > Wikipedia image >source http://.flickr.com/photos/fotoosvanrobin/3277764542/ author FotoosVanRobin from Netherlands 

Milk is a common example of an oil-in-water emulsion. Cream and Butter are both material combinations with same substances, but in different proportions. A Cream is oil-in-water emulsion whereas a Butter is water-in-oil emulsion. Their tastes and textures are though very different. Emulsion products include mayonnaise, margarine, hollandaise, icing, fillings, chewing gum, confectionery items, face creams, skin lotions, make-up products, hair dressing products, dyes, tanning compounds, medical formulations, lithography inks, oil bound distempers (*OBD), and plastic or latex paints. Emulsions deliver a liquid product dispersed in a carrier liquid to reduce the cost, disperse the applied material and add body to the formulation.


Shaving Creams consist of an emulsion of oils, soaps, or surfactants and water> Wikipedia image by Coffeeaddict

Emulsions are formed and maintained by single or combination of processes like: Addition of an emulsifier, Mechanical mixing, Thickening agents and Heat energy. Stable emulsions can be undone by nullifying the effect of the emulsifier through chemical agents, freezing or high temperature heating.

Emulsifiers: An emulsifier makes the emulsion stable. Addition of surface-active agents reduces the interfacial tension between the dispersed and the continuous phases.


Body Creams and Lotions > Wikipedia image by Gryffindor

Mechanical mixing: Vigorous stirring with or without stirrer blades causes the dispersible phase into finer droplets to form suspension in the continuous phase.

Thickening agents: Such agents increase the viscosity of the continuous phase, which prevents the movement and coalescence of dispersed droplets. Nominally emulsions have higher viscosity then their individual ingredients. Most emulsions are shear-thinning fluids where vigorous stirring can reduce the viscosity.

Heat energy: The viscosity and interfacial tension of the dispersing phase is reduced by heating.


Ancient manner of Butter making in Canada > Wikipedia image

Transparency and Colour of Emulsions: The size of the droplet of the dispersing phase affects the light reflection, changing its transparency and colour. Emulsions are cloudy or milky in appearance when disperse-phase is of finer droplets. If the droplets are very large, then it is closer to simple dispersion or suspension. Emulsion paints are added with thixotropic agents that lower the viscosity on stirring before application, but on storage gain high viscosity to prevent settling of pigments.

Micro-emulsions are thermodynamically stable because the dispersed phase is 0.01–0.2 µm in size. Such emulsions have a characteristic transparency as their droplet size is <25% of the wavelength of visible light. Micro emulsions are stable due to the small size of droplets and high proportion of surfactants in the formulations.


Screen printing Binders are Acrylic emulsions > Wikipedia image

Polymeric emulsions came into commercial use post 1940s. These are prepared with water as the phase, and stabilized with surfactants (molecules that are hydrophilic (water-loving) in one phase and hydrophobic (water-hating) in the other phase). The polymeric emulsions have very high molecular weight, and so when the water phase evaporates polymers coalesce into a tough film. Plastic or Latex paints as known in USA are plastic paints with polymeric emulsion-based formulations. First acrylic emulsion based ‘binders’ were produced for leather and fabric printing, but soon began to be offered as architectural coatings. Plastic paints were formulated at a time (1940s) when solvent-based paints made with alkyd or linseed oils ruled the markets. Oil paints’ were odorous, toxic, and flammable. Early acrylic paints didn’t bond well to ‘oil painted’ surfaces. Acrylic emulsions offered non yellowing, non cracking, environmentally safe, odourless and non-flammable system.

Plastic Paint

Acrylic Plastic paint application > Flickr image by http://www.charlesandhudson,com

Acrylic emulsion paint formulations are costly to produce in comparison to ‘oil-based’ paints, and other ‘plastic paints’ such as of Vinyl and PVA (polyvinyl acetate) systems. Interior emulsion paints have high vinyl and low acrylic contents. A paint with a high acrylic content will have much better water and stain resistance.

‘Emulsifying effects’ since prehistoric times, have now developed into science of fluid behaviour and mixing. The term emulsion has become synonymous for liquid-mix systems, and is used to designate solutions, suspensions, or gels.



Post 576by Gautam Shah


A space is recognized and improvised, or designed for a range of behaviour. A lay-person recognizes and improvises, or the expert, who designs it, can only surmise how it will manifest. The stack holders, Designer or the user, are often not aware of the basis of the recognition, improvisation or design, yet all do arrive at common realization.


Wikipedia image by Ulrich Lange, Dunedin New Zealand


The spaces have Two distinctions: Exteriors and Interiors. Exteriors have Two distinct zones: One where the extent is endless and beyond the perception limits -‘the wild exteriors’, and, Two where the edges limit the perception creating ‘neighbourhood spaces. Interiors have Core and Peripheral zones. ‘Threshold areas’ manifest between the exterior and interior realms.


Exterior spaces have highly variable environment and territorial presence. There is virtual immediacy of the two realms. One cannot conceive the Interior or Exterior alone, without the other being present in time and space proximity. This proximity is however achieved by design, by carrying across the impressions of the other. The Internal and External spaces, can occur as a ‘metaphoric concept’ for the other. The duality of the interior and the exterior is like an antithetic zone to the other.

The heaven and the hell are two surrounds of the earth. Egyptians have dummy doors (drawn or carved) in their tombs. A Garbha Griha in a temple is an inner sanctum. The Japanese gate Mori is placed anywhere, in a vast open land or sea, to mark a divide. Lakshman Rekha was a notional boundary.


Wild Exterior Space > Wikipedia image sourced from geograph.org.uk > by author Adam Ward

■ Wild exterior spaces: Very vast exterior spaces are perceived for the endless sensorial ‘effects’. A ‘beautiful sunset, a valley or seashores’ are markings of a space. Markings denote the natural extent of a wild exterior space, but the same may not be perceptible. These are, though evident through the physical elements like: edges, banks, thresholds, slopes, plains or fences and environmental effects thereon. We perceive only certain range of space. The reach capacities vary with perceiver’s  capacity, needs and environmental conditions and so are circumstantial. The behaviour with reference to markings, is perfunctory, as it relates to only the potential –what can one do with it?

A wild exterior space defined by the markings is an infinite realm. It cannot be a setting for personal or interpersonal behaviour. One can perhaps realize a potential to possess it.

These are few quotes taken from historic text documents that describe the markings of Land-Spaces. US President Thomas Jefferson insisted that the purchase included ‘all land to the east of the Rocky Mountains and to the north of the Rio Grande’. ● The (Spanish) missions were located in a disputed area; France claimed the Sabine River to be the western boundary of Louisiana, while Spain claimed the Red River was the eastern boundary of Texas, leaving an overlap of 45 miles (72 km). ‘From the point on the north bank of Muddy Creek one mile above the junction of Muddy and Indian Creeks, north for 400 yards, then northwest to the large standing rock, west to the large oak tree, south to Muddy Creek, then down the centre of the creek to the starting point.’ ‘Lying in Anson County, on the side of the Atkin River, beginning about a mile below the fork of the fourth creek that empties into the said river, above the waggon ford, running up the said creek for complement, including an Indian Camp about eight miles beyond the path that crosses the buffalo licks.’


Esgaroth or Lake Town – a fictitious neighbourhood community that appears in novel The Hobbit (1937) by J R R Tolkien > Wikipedia image work source Angrenost.cz by Neral (Matej Cadil)

■ Neighbourhood spaces: Neighbourhood spaces come into being and remain valid in the dual context of interior spaces on one hand, and the wild exterior spaces on the other side. The neighbourhood becomes ‘a place for everything that an interior space cannot offer and an experience that cannot be had in the wild exterior space’. It becomes a place for informal social contacts. Markings here help create anchor points, line-links and extent spreads. These are also definitions to dimension, grade, scale and proportion the space. The elements represent an exclusivity through a change such as a drop in terrain, contours, variation colour or texture, illuminated or shaded objects, etc.

A neighbourhood as an exterior space is finite and predictable. It is both a ‘collection of individuals and a place, the people who live there and the place itself’. Here the social ties develop not just due to people involved, but due to the setting of the place. Neighbourhood spaces have recognizable geometric order or a predictable configuration, purposive locations for anchorage, well-defined zones, distinct routes and paths, good visibility (and other clarity of other sensorial perception) and recognition of the whole and its parts.


UNESCO > neighbourhood village of Holloko Nograd Hungary Wikipedia image by Bardos Veronika Gyor hu.wikipedia

Neighbourhood spaces are known through their limiting elements. These elements restrict continuous perception or environmental effects. The bounding elements indicate the purpose of the space, and in many cases even the nature of its ownership, and structure of administration. In the neighbourhood the depth or scale is defined by the reach capacities such as vision, hearing, smell, touch, etc. These elements individually represent varied form of reach, so space definitions here match to the purpose.

– ‘a jungle of apartments where no one knew who was dead or who was celebrating what – but an archipelago of neighbourhoods in which everyone knew each other.’ -Orhan Pamuk, Istanbul: Memories and the City.

Neighbourhood spaces have paths and open spaces that both connect as well as separate various habitable spaces. Here it is not the distance but the degree of dependence that forms unified neighbourhood space. The dependence is a need based as much as it is perception based. One may not know or formally meet the neighbour for years, or ever, but the perception someone is staying in vicinity is a great social comfort. Very often even the presence of a man-made object provides the same comfort.


A street tunnel underneath the Mexican city of Guanajuato > Wikipedia-Flickr image by Jorge Ibarra


Interior spaces are enclosed entities formed by the edge elements such as shell, roofs, coverings, awnings, curtains, partitions, ceilings, etc. These are spatial definitions that create a dimensioned interior space. “A space created by the enclosure is far more enduring then one defined by bounding”. The enclosures have varied levels of transparencies and the openings within the shell allow connections to the exterior. The transgressions occur as outward push and inward pull of the interior space. The outward push or encroachments are often ‘cost-less’, though may ‘load’ the enclosure (shell) body. It increases the interior volume and permits a restrained exterior experience. The inward intrusions, however, consume interior space or estate and reduce the available enclosed space.

Examples of outward transgressions: Galleries, balconies, Chhatris, campanile, bay-windows, oriel-windows, dormers, Mashrabiya, verandahs, skylights, etc.

Examples of inward transgressions: Cutout, Chowks, courtyards, Liwan, setbacks, cutbacks, shafts, light-wells, etc.

The outward sensorial reach beyond the edge of the interior space does not affect either the wild or neighbourhood exterior spaces, but the interior spaces are affected by the happenings in exteriors. A ‘wild exterior space’ due to its uncertain character and infinite size, cannot be possessed. A ‘neighbourhood space’ lacks the complete settings and environment for all types tasks other then the casual social interaction. But an interior space is controlled and a domesticated entity, and so allows many varied activities. The form and format of the interior space are unitary and consistent, but the subsections show minor, local and temporary or circumstantial variations.


Core versus Peripheral zones in Interior Spaces > Wikipedia image attribution -share alike 3.0 Austria license

■ Core Zones Interior Spaces: Interior spaces have an insulated and static segment as its core zone. The core zone is nominally centric, but to be focal, extensive and an important point, it may be shifted towards one of the edges. At the core segment metaphysical elements like concepts, beliefs, taboos, etc. that reflect the essence of the inhabitation are stronger.


Peripheral zone in Interior space -Boeing’s CST-100 spacecraft Wikipedia image

■ Peripheral Zones Interior Spaces: Peripheral zones abut the built edges of the interior spaces. As the enclosing elements have varied levels of transparencies and the openings within the shell, connections to the exterior are vibrant. These are multilateral entities, reflecting the environmental variations. Where such variations become extensive and a permanent a new spatial entity comes into being. In peripheral zones metaphorical elements like signs, symbols flourish.

For example, cooking-dining, kitchen-bathing, entrance-living room, etc. have been adjunct as well as segregated entities, at different times, and within same era for different social reasons.


Ponnu School Verandah India > Wikipedia image by Mohanavel


The barriers define shape, size and environment of the interior space through their constitution, thickness, mass, volume, size, absorbency and transparency. Thresholds occur at openings, cuts and cleavages of enclosing elements. Enclosing elements have degrees of transparencies and discontinuities and effectiveness of the threshold is determined by its size, shape, location and orientation. The divide, represented by the threshold may not be a clean edge-cut, but could also be an extensively graded formation. Thresholds can have real or hypothetical realms, but usually have abutting structures to create an intermediate climatic zone and intermediate spaces.

A threshold may be an abstract divider in space like the Laxman Rekha but a change marker. Thresholds are marked by change in quality of flooring, illumination, sidewall configurations and by elements like high sill, steps, opening portals and pediments. Architectural attachments like verandahs, canopies, overhangs, otalas enhance the threshold’s functions. In thick-wall structures, openings get a substantial depth creating an interpersonal space as in gates and gateways, or in windows a shading device on external sides or an illumination diffuser on inside. In Kutchh Bhunga houses doors are predominantly South (windward) face and women folk occupy the threshold for craft and household work.


Threshold- Buffer area at Entrance of Palika Bazar Connaught Place Delhi > Wikipedia image upload by Ekabhishek and Image by Johannes Bader


This post forms 6th of the Sixteen part of Lecture series on Behaviour in Space that I will be offering for the spring semester starting Jan 2016 (to mid April2016) at School of Interior Design, Faculty of Design, CEPT University, Ahmedabad, India.



Post 575by Gautam Shah


Masking is an overlay on an opening such as a window, door or gap. The overlay could be an additional system, opportunistic exploitation of the surroundings, or an arrangement for doctoring the perception. There is an attempt to change the quality of view, such as increasing or decreasing the clarity of view; add directional emphasis, such as horizontal, vertical or some other direction and alter the proportion and scale of the view; to divide the view into smaller geometric or floral sections and to camouflage or conceal the opening itself, the shape, location or purpose.

Framed View

Framed View through Opening > Pixabay image

Masking of openings happens over the gap portion, but Framing of openings occurs on surrounding portions of the gap. Masking and framing often serve similar purposes, which are of camouflaging the shape of the opening. Shape modulation also affects the size perception. Openings gain a tectonic meaning in consonance with the site, the environment, people and other building elements. Primary framing takes place, on how an opening is composed within a barrier system.


Door Framing II nd Floor Balcony at Palace of Raio > Baroque era Residence at Braga, Portugal > Wikipedia image by Sara silva

Technologically shutters of doors and windows, pivoted or hinged, have been square edged. This in turn forced the shape of openings to be square edged. Doors, windows and gaps, till about pre-gothic period were overawed by the powerful geometry of the squared edges. The only option was to taper the faces of sides and bottom sill. Lintel bottom remained flat, being structurally inviolable. Occasionally stepped or layered lintels were used.

Gothic Tracery

Gothic window tracery St Mary Church, Snettisham, Norfolk, England > Flickr image by Spencer Means

Square lintels or the round arch-vault, was a necessity for massive Romanesque structures. Gothic period, however, saw some degree of liberation from the square cornered rounded arched openings, mainly due to the thinner walls and use of pointed arch. But this advent was accompanied by shutter-less fixed glass openings. The shuttered opening like doors, however continued to have squared lintel heads, framing and shutters.


Serrated door Framing Amiens Cathedral > Wikipedia image by Mattana

The square edge, for the first time was consciously and successfully dissolved during the Rococo period. The Rococo period had two important facets: Motifs over interior face of openings in the form of painted stucco work, and architectonic elements and sculptures over the exterior face of the opening. This integration of elements over the openings, however, never transgressed the square edges of the frame or shutter. It had to wait till Art Deco and Art Nouveau periods when few adventuresome breached the omnipresent straight lines of the openings.


Masking and Framing of Door at Art Nouveau Building from architect Jules Lavirotte Paris France Sculptures by Jean Francois Larrive 1875-1928 > Wikipedia image by Pline

The framing transformations first occurred in the print media, artwork and jewellery items like photo-pendants. Photo and painting frames continued with the squared edges on the inner face. These were of Two types: Tapered inward or outward. Over the period all forms of frames drew inspiration from each other.

1 Frames_France

Photo Frame 18 C > Wikipedia image by FA2010

2 Frame.png

Photo Frame 18 C France Wikipedia image by FA2010


Flickr image by Plum leaves


Photo image Florence > Wikipedia image by FA2010


Door Frame emulating the Photo Frame 18th C Venice > Wikipedia image by Hiart

Few Art Nouveau experiments altered the door frame and shutters with floral ingress. These experiments saw 3D modulation and integration of the architectonic elements along with masking and framing appendages. These were craft and technology based multi-material solutions devised along with the form of the building -in a way an integrated architectural resolution.


Bloomsbury Tavern Night view of windows > Flickr image by Eric Huybrechts

Openings have a dual personality, of the inside and outside, and both have been differently treated for functional, technical and scaling reasons. The framing references are different for both. On the interior face great many masking elements including soft furnishings are available to condition the view outward. The options on outer face are fewer, but major one is the day time perception of the opening, in complete contrast to inside illumination at night time.

Ney York Times Night View

New York Times Building NYC Night time > Wikipedia image by Jleon (talk)

The masking of view out or inward, is done through real or make-believe depths formed by repetition of series of identical, receding or increasing frames. Such multiple frames occur in colonnades, corridors, passages, avenues and walkways.


Corrodors of Miranda House Delhi. Repeat elements framing the view >Wikipedia image by Dell335

Framing can provide its own third dimension, or the depth aspect to the opening. The depth aspect was primarily used for inducing a perspective view. Framing took advantage of depth of the massive structure, such as in Romanesque period. The sides, top and bottom edges of the openings, on both the inside and outside faces, were chamfered or cut square. The additional surfaces of intrados and extrados were articulated to not only enhance the perceptible extent of the opening, but treated with sculptural texture for adding to the extent of a visual surface. Side surfaces of the openings created a frame within frame.

..92 durch ..94 ersetzt

Pediment over openings Siracusa Cathedral Sicily Italy > Wikipedia image by pjt56—




Post 574by Gautam Shah


Domains are nominally, Physical, Metaphysical and Metaphorical. At another level domains could also be Real or Virtual. Physical domains are landed or with dimensioned and marked territorial features. A Metaphysical domain is more relevant by the spread or extent of its activities or effectivity. Metaphorical domains subsist on analogical connections. Such domains rely on thought, concept, traditions, customs, beliefs, style, ethnicity, etc.


Spatial Domain > Wikipedia image by VeronicaTherese

A space domain has few distinguishing marks, such as the Core and Peripheral zones. Space domains are proximate or converge. Domains have users and their social interactions are triggered by the spatial organization of the domains. In the following FOUR articles, these issues are discussed.









Monte Alban Archaeological site Gran Plaza Oaxaca Oax, Mexico Wikipedia image by Hajor Released under cc.sa and/or GFDL

Physical domains are landed or with dimensioned and marked territorial features. Physical domains have transient core and peripheral zones. The peripheral zones react with the local environment and so can have many spatial as well as temporal variations. Core-zone is a common or community area and continuously shared with others. Core-zone accommodates relocatable amenities. Compared to this, the peripheral areas are assigned to specific tasks, but the tasks shift around to take advantage of changing environment. The house in charge person, wife, mother or in few instances home-based craftsman occupies the core area. Enrichments occupy the boundary sections and define the space such as sanctimonious, utilitarian, storage etc. The core area often shifts towards the daylight zone near openings.

The markings of domains are characterized by the ambit of sensual perceptivity, communicable distancing, consistency of the spatial characteristics (coherent space and environmental conditions creating a unique space segment) and acceptability or confirmation by a section of the society.

Metaphysical domains have a non physical spread. Such domains cannot be perceived through the sensorial system. Their presence is intellectually and intuitively confirmed by the believers, but for others it remains obscure. Such confirmation requires a unitary image, so a strong centric core zone emerges, often with a definitive peripheral zone. To reflect the enhanced participation and democratic nature, the peripheral zones are made transparent.

Revered spaces, shrines, historical sites, haunted buildings, buildings without utilitarian functions or commercial purposes have a strong metaphysical genesis. Beliefs borne out of instincts, concepts, experiences, etc. are rooted to the core area. In the peripheral or threshold areas these have thinner effect, so are impacted by the ideologies flourishing in the neighbourhood. Inhabitants’ beliefs also may be born as a reaction (antithetic) to the neighbours’ ideology, and in such cases may not have any core roots.

Metaphysical entities like home, family, group etc. come into being in a space where communication, exchanges and the intimacy occur more efficiently then elsewhere. Such space units are also ‘home’ to many other beliefs and notions. These are associated with a person or group, and so have a strong presence. Metaphysical zones centering on a belief or remembrance of an event, person or entity are sustainable so far as believers, followers exist, conduct activities to further the belief or notion, or till a counter effect comes to be accepted.

The beliefs as a metaphysical factor cast a space that is sharper at the point of the origin, and prone to diffusion elsewhere. But for belief to survive and gain strength peripheries are necessary. Churches, temples, Ashrams have strongly defined territory through peripheral structures like gates, walls, Gopuram, etc.

Metaphoric domains require very little estate, however to support and enhance the metaphoric presence some spatial characteristics are employed. There being a single generative concept, the peripheral zones have a very small role and so a thin presence. The environment within is static, reflecting nearly solid barriers. Amenities, facilities and enrichment are purposive only, and so their relocation or any shifting of other elements due to them is not required.


Global Internet Realm > Wikipedia image by Shijan Kaakkara

 Convergent or Proximate Domains

A physical domain is a unique spatial entity. But often other domains are very close-by or converge onto it. The effect of it is seen as inward and outward transgression of the peripheral areas. The transgressions occur to enhance the spatial character, or take advantage of the neighbouring or convergent domain. Ariel windows, Bay windows, Chhatris, Balconies, Verandahs are typical outward transgressions, whereas Chowks, cutouts, shafts, courtyards, are examples of inward transgressions. With such transgressions the peripheral areas change, but core zone remains unaffected. Perhaps the only change that occurs with the core zone is due to the shift towards the vibrant periphery.


Convergent domains Edinburgh Castle and surroundings > Wikipedia image by Kim Traynor



Domains have Three basic constituents Formatted Space, Environment and Individual/s. A domain, as a space, is a segmented entity. Its primary segments are Core and Peripheral zones. A core is usually single, but peripheral zones are many. The core and peripheral zones often converge. Different peripheral zones also impinge over each other. The formatted space endows an exclusive character to the domain.

Core Zone of a space domain represents the commandeering mechanism and has a natural tendency to be singular and focal. The core zone has consistent environmental and spatial qualities, but its position within the domain may be transient. The shift is due to environmental conditions, functional needs, available facilities, amenities and enrichments.


Core versus Peripheral zones Flickr image by Stortinget

Core zones gain strength by the shape (form) of space. Space forms like concentric, conical, angular, circular etc. are focussed and so enhance the nature of a core zone. However, very extensive domains lack an effective focus. A dominant enclosure on one or few sides of a domain creates an inviolable shield, an identity of belonging, or a sense of orientation.

A core zone can be formed by the dimensional and cognition reach extent of the occupant. The reach extent also scales the domain space. Such core zones are very personal, so sustain themselves independently. A core zone may not exist clearly where very vivid surroundings form strong peripheral areas.

Core zone amenities shift due to spatial needs and environmental changes. This leads to demountable or relocatable amenities such as handy or mobile tools, multipurpose equipments, plug in tools, wireless gadgets, miniaturized appliances and modular and system’s engineering approach in design. Compared to these amenities in the peripheral zones are strongly dependent on the architectural and structural systems, and so are static.

Historically a core zone of the ‘Home’ was the ‘hearth’ (literally meaning a focus). It was considered safe, intimate and interactive for the family. The hearth was centric, without any abutting elements like a cave wall or a rock face. The ambit of the core zone was determined by the climate, the scale of the space, number of participants and level of interaction, and the degree of personalization required. There was only one such zone in the dwelling.

The home in charge -the mother was master of the core zone. Her role and presence had become so obvious that ‘the hearth, the mother and home’ were synonymous. In tribal and aboriginal homes the core area is a female domain. The core zone, was the natural centre of metaphysical spread ‘the home’, as much as the mother was de facto guardian of culture.

Today, however the hearth is not an inevitable element for safety, security or comfort. It is the quality of barriers and other gadgets that provide this. Dwellings now have many sub domains each belonging to an individual, smaller group, or configured for a set of tasks. Very few activities of the family occur at the one place and are scheduled in the same time slot. But the family members do share a lifestyle developed through metaphysical markings like beliefs (customs, taboos, etc.) and the metaphoric means.


Multiple or Convergent Core zones at Water Tower Place Chicago > Wikipedia image by Cosmos1976

Multiple core zones occur in very extensive domains. Such domains have weak central command and so allow formation of groups. The groups separate out primarily due to needs like physical accommodation, need for social intimacy and reach of communication. The groups may not seek a distinct territory or qualitative space segment, however, frequent such occurrences, show the existence of multiple qualitative space segments.

Multiple core zones also emerge where several overlapping or closely spaced domains operate within a larger domain space entity. Such core zones share the same spatial segment simultaneously or are programmed in same time schedules. Here the consistent elements are: spatial characteristics, environmental features, participants, amenities, facilities, tasks and activities. Multiple core zones tend to remain together, but often get separated by strong peripheral areas.

Arab tents had dual core areas within the basic form of the tent, one occupied by the women and used for main cooking, and the other half is used by men and for preparing coffee, etc. These two sections are divided by a mass of stored elements, such as mattresses, floor spreads, etc. The side flaps of the tent are stretched out to create peripheral zones of various sizes. The stretched width and the angle of the flap are conditioned by the sun’s position, wind direction, nature of tasks to be conducted and the need for privacy.

Cooking and dining once (and still do in many societies) belonged to a single core zone, but were separated as two concurrent core areas. These two core areas were further separated by a pantry area that was a peripheral zone to both. Entrance is buffered by a lobby, foyer, entrance hall, or vestibule from other sections of the house. Yards, verandahs, porches are used to separate out the building from the street.

Small or one room houses have multiple core zones. These zones exist in terms of activity space spreads, which often overlap in time. The multiple core zones match the space layout characteristics, such as four corners, the area near the door or window, the area abutting the wall, the axis formed between two opposite side opening. Traditional Sarai rooms are two and half man width (2.0+1.0 mid passage+2.0 = 5 Mts or 16.5 Ft). This allows two families or their men or women to occupy a side. The depth of the room is of less important.


Centric Core zone A Pompeian Interior > Wikipedia image

Centric and Non-centric Core Zones: Domains with emphatic barriers create a centric space entity. But domains with breach-able barriers or loosely defined peripheral identities have overwhelming outside influences that create a non-centric space.

Domains with a substantial core zone tend to be spherical. Such spherical domains with a centric core zone are invariably static, compact and finite. Domains with an opaque boundary are also similar. Domains with weak boundaries have vibrant peripheral areas. A shift of the core zone towards a benevolent peripheral area becomes inevitable. A very extensive domain also provides greater opportunity for such a shift. Non-centric domains have some directionality as these are strongly affected on one edge, or are attached to other domains. Non-centric domains require far more definitive space formatting then centric domains.

Historically kingdoms have had effective spread of their domain depending on how far and fast they could travel. Mughal kings with their luxurious retinue could not visit the peripheral areas, frequently resulting in weaker control. Compared to this Changiz Khan’s Kingdom extended far & wide, but not for very long. Lecture halls or areas where concentration is required have opaque boundaries and conical shape. A colony against a fort wall or along a river coast is a linear domain, subsisting on the strong peripheral advantage and so apparently may not have core presence.



Peripheral zones are vulnerable to outside influences due to their closeness with the edge and also their distance from the core section. A core zone is dominated by the domain’s main and common activity, but the peripheral zones are distinctive escape areas and so have diverse utility. Peripheral zones derive their functionality from nature of barriers. Peripheral zones emerge as an antithesis or concurrent space segment of the core zone. The peripheral zones are affected differently by the directional and temporal aspects of the environment. A peripheral zone is often relevant only for a while, to an individual, or for an activity.


Peripheral emphasis in space > Choir and East side of the rood screen of Saint Cecile Cathedral France > Wikipedia image by Benh LIEU SONG

Once the extent of the peripheral zone was determined by the concern for safety, warmth from the fire, the need for privacy, scale of the task-activity and distancing from elements (to reduce their intensity and reach). The barriers, where available formed the edge sections of the peripheral zone. These were also used for reclining, resting, hanging personal items and for expression (artwork).

Peripheral zones are primarily shaped by the core zone, but are more often affected by the nature of the periphery of neighbouring domains and happenings beyond. The edge areas allow a person to selectively taste the happenings of outside-world even while remaining inside. Peripheral zones are flexible, i.e. can be stretched or contracted from their nominal spread. Domain transgression occurs through the periphery. Peripheral zones are dual faced, so one can orient an activity towards or away from the core area.

Peripheral zones often develop as an acutely specific zone. Study nooks in bedrooms, coffee rooms with the dining area, hobby zones in kitchens, home offices with vestibules, retiring rooms in private offices, vaults in banks, store rooms with homes and offices, wardrobes, shower stalls, change rooms in boutiques, cashiers’ cabins, pilot or driver’s cabins, reception counter, janitor area, services ducts, podiums in lecture halls, green rooms with a performance stage, ticket booths, telephone kiosks, are all examples of peripheral zones separated from the core zones.

Peripheral areas mark the end of one space entity and beginning of another one. Peripheral zones are thresholds to other space entities, and occur or are perceived to be an intermediate or buffer state. Thresholds are interactive areas, and alter (qualitatively) the elements transiting through it. Their activeness arises from their level of transparency and thickness (mass of the barrier), both of which control (rate, direction) the exchange. Thresholds also occur as an interstice on the overlapping barriers, where two effects are simultaneously operative.

The space barriers, such as walls, roofs, awnings, curtains, partitions, ceilings, etc. form a focussed space. Yet these barriers also create segments that are more strongly attached to the periphery. The barriers, however, are always prone to change from outside effects. There are two distinct places for group behaviour mechanisms -the focal and the peripheral sections.

Lecture halls, bed rooms, modern kitchens are single activity and so focussed units, but road side cafes are peripheral. An older style kitchen sourcing its services off a wall was more peripheral, whereas modern kitchens have island workstations, is more of core centric arrangement. A drawing room like the dining area is focussed for an activity, but a family room is multi functional and so less focal. Fire was the focus of the primitive home, and TV has become the current focus of home gathering. A physical feed-based work station is peripheral, but a wireless notepad computer offers flexibility of being anywhere.



Domains as Space entities are used by owners or occupants, architectonic elements and spatial objects.

Space and Users or Occupants: For a user, occupation of a space triggers a set of behaviour. For occupation the user has to find the most appropriate location, orientation, body posture, facilities, amenities, and environment. One of the most natural and primal way is to search a focal location in the space. This is done by finding geometric junction (cris-cross of many spatial lines), by locating spatial balancing or focussing centres, by orienting to some feature of the space (like an entrance door, window), by being closer to something (wall, column, furniture), by associating with other occupants (through ‘social distancing’) or by creating new patterns (angular, floral, concentric, diffusive). Here other operative factors are: range of cognition (capacity to perceive), physical proximity (level of social interaction), nature of relationship (age, sex, social status) and possibilities of expression and communication.


Pennsylvania Station NY > Wikipedia image by Alan Turkus

The user also needs to have some control over the space, such as: Opportunity to change the location and position (including the posture) within the space; Choice to interact or not with others; adjust the spatial quality at micro level (scale and schedule-wise) and thereby the environmental conditions; Be noticed or notice others; Form sub-core zones, Shift to peripheral zones and be able to conduct exclusive tasks, and Way to leave the space either in full knowledge of others or without being noticed. A user, unless is an owner of a domain, will not be allowed to change the architectonic character of the space, import, shift or relocate amenities and facilities, alter the quality of environment that perhaps is not acceptable to others.

In very large spaces adjacent walls, hedges, mid columns, flower pots, water fountains, lamp posts, flooring, ceiling, and such other patterns and objects provide points of anchorage for space occupation. Spatial configurations like a stage, podiums, projection screens, speakers, singers, vivid objects, also hold interest by providing involvement.

In parties, hosts make a conscious effort to break intimate formations by removing or adding key or active persons, or repositioning and rescheduling the activities. In clubs and places of entertainment the environment (lighting, furniture, equipment) and programmes are reset to shift the focus off certain space segments. Group gatherings are designed to occupy different space segments (hall, terrace, lounge, library, garden lawn, etc.), variegated environmental conditions (bright vs diffused illumination, change of music, etc.) and diversions (toast by the host, magic shows, musical renderings, dancing, etc.).

Interpersonal Relationships and Spaces: Groups require space for interpersonal relationships, expression and its perception. However, the ‘depth’ required for such interactions in physical domains is irrelevant for virtual domains like telephony or video conferencing, chat rooms, hangouts, etc.

Interpersonal relationships have little relevance in acutely sized and highly defined spaces (ergonomically sized, shaped and provisioned with facilities), such as: toilets, kitchens, storerooms, study nooks, booths, etc. Larger spaces such as bedrooms, drawing rooms, office cabins, etc. allow interpersonal relationships, often in multiple varieties simultaneously.

Ideal place for the interpersonal relationship is the core section. This has least external disturbance, so should be an area of tranquility affording privacy. Yet peripheral zones are more preferred as a place for intimate relationships and commitment. In restaurants, cinema halls, public parks, large waiting areas, people move to corners and edges for seclusion. Threshold areas though peripheral, are public and vibrant. Threshold areas are considered ideal for noncommittal interaction.


Group behaviour mechanism in Space Image Flickr source: Neko II > Wikipedia image by Sultry

The group behaviour mechanisms exploit the space characteristics to infuse emotional and social functionality. Group behaviour depends on individuals as well as interactions among such individuals. An individual projects psychological and sociological responses. The group behaviour though erratic has a degree of commonality – raison d’être (cause) of formation of the group. The common approach of the group is an assurance that their peculiar behaviour is not an aberration but a probable happening.


This post forms 5th of the Sixteen part of Lecture series on Behaviour in Space that I will be offering for the spring semester starting Jan 2016 (to mid April2016) at School of Interior Design, Faculty of Design, CEPT University, Ahmedabad, India.


Post 573by Gautam Shah


Materials have three fundamental states of matter, namely Gas, Liquid, and Solid. The state denotes the structural rigidity and resistance to changes of shape or volume. The state or phase of a matter is due to the temperature and pressure. Most substances are solid at low temperatures, liquid at medium temperatures, and gaseous at high temperatures. The state or the changeover of a phase is not always distinct. The temperature at which any given substance changes from solid to liquid is its Melting point, and the temperature at which it changes from liquid to gas is its Boiling point. In the reverse order the Gas to a Liquid transition is known as Condensation, and Liquid to Solid change as Freezing.


Mixing Oil, Vinegar and Mustard for whipping into emulsion > Wikipedia image by jeffreyw

Solids have molecules held very close to each other, and so maintain the rigid form without any need for a container. Solids formed by slow cooling have constituent atoms, molecules, or ions packed in a regular order and are called crystalline. Solids cooling down very rapidly have no long-range order for the position of the atoms and so have amorphous structure. Solids can be broadly categorized as organic (Such as the wood, paraffin wax, naphthalene and a wide variety of polymers and plastics) versus inorganic (such as metals, alloys, minerals). Solids are formed when definite bonds exist between component atoms and molecules.


Air entrained coffee of South India > Wikipedia image by Babithajcosta

Liquids are mostly non-compressible fluid, able to conform to the shape of its container but able to retain more or less constant volume irrespective of the pressure.

Gases are compressible fluids able to take the shape of the container by expanding (or compressing) to fill it.

Plasma is the fourth state of matter following solid, liquid, and gas. Plasma is an ionized (electrified) form of gas. It has a collection of charged gaseous particles containing nearly equal numbers of negative and positive ions. Unlike other gases, plasma may self-generate magnetic fields and electric currents, and respond strongly and collectively to electromagnetic forces.


Plasma cutting machine Wikipedia image by Steve Brown Photography

Compounds are combination of materials in the same or different phases. Compounds can be separated by a chemical reaction. If a compound is uniform, it is called Homogeneous, and nonuniform compounds are called Heterogeneous. Homogenization is a process of distributing one substance, uniformly throughout another (Ice creams, ketch-ups, etc. are homogenized). A mixture is made from molecules of elements and compounds that are simply mixed together, without chemical bonds. Mixtures can be separated using techniques such as filtration, chromatography, evaporation and distillation.


Salt + water solution > image attribution: Chris 73 / Wikipedia Commons

Solution: Solution is a homogeneous mixture of two or more substances. The substance present in larger quantity is usually called the solvent, and the other substance present in smaller quantity and dissolved is called the solute. The solvent can be either a liquid or a solid and the solute can be either a gas, a liquid, or a solid. Carbonated water is an example of a Gas (carbon dioxide) dissolved in a Liquid (water). Mixtures of gases, such as the atmosphere, are sometimes referred to as solutions as well. Solutions are distinct from colloids and suspensions in that the particles of the solute are of molecular size and are evenly dispersed among the molecules of the solvent. Solutions appear homogeneous under the microscope, and the solute cannot be separated by filtration. Salts, acids, and bases ionize when they are dissolved in water. Certain metals are soluble in one into another, in the liquid state and solidify with the mixture of atoms preserved. If such a mixture can solidify for different proportions of the two metals, they are said to form a Solid solution of metals.


Compounded materials occur in following forms: (Medium in Phase)

  • Solid in Solid > Alloys
  • Solid in Liquid > suspension, solution, dispersion
  • Solid in Gas > smoke, airborne dust
  • Liquid in Solid > gel
  • Liquid in Liquid > emulsion, mixture
  • Liquid in Gas > fog, aerosols
  • Gas in Solid > solid foams
  • Gas in Liquid > froth, liquid foam, aerated soda
  • Gas in Gas > atmospheric air

Cutting tools of Alloys > Wikipedia image by Glenn McKechnie

SOLID in SOLID  A solid solution is a solid-state solution of one or more solutes in a solvent. Solid solutions occur in nature as minerals formed under heat and pressure. It is formed when two metals are completely soluble in liquid state. Typically Brass has copper (64 percent) as the solvent atoms and zinc (36 percent) are solute atoms. Such a mixture is considered a solution (rather than a compound) when the crystal structure of the solvent remains unchanged by addition of the solutes, and when the mixture remains in a single homogeneous phase.

SOLID in LIQUID  Salt or Sugar get dissolved in water forming a Solution. Solution like, amalgams (mercury in silver) are uniform throughout and are homogeneous. On the other hand Sand, Rocks, and wood form heterogeneous mixture where each constituent retains its own chemical identity and properties. A suspension is a heterogeneous mixture containing solid particles that are larger than one micrometer for sedimentation. Colloids have finer suspended particles and do not settle. For suspension to occur some excipients or suspending agents or mechanical agitation is required.


Smog at Brighton UK by Wikipedia image by Richard Rutter

SOLID in GAS: Very small particles (less than 0.002 mm) can float around in air and larger particles (greater than 0.5 mm) roll along closer to the ground. Smoke and airborne dust are solids in gas medium. The process is used to separate particles of different sizes through mechanical cyclonic effect.

LIQUID in SOLID: Gels are dispersion of molecules of a liquid within a solid. The solid is in continuous phase and liquid is a discontinuous phase. Liquid in solids combinations also manifest when excess amounts (than required for equilibrium) of solute are added to a liquid, a condition called super-saturation occurs. Supersaturated solutions are unstable, and may remain in that state for an indefinite period of time if left undisturbed. However, when solid particles are added at this stage, it encourages crystal growth. A sol is a colloidal suspension of very small solid particles in a continuous liquid medium. Sols are quite stable (often due to presence of dispersion agents) like the blood, pigmented ink, cell fluids and paints. Artificial sols may be prepared by dispersion or condensation.


Hai dressing gel > Wikipedia image by Bangin

LIQUID in LIQUID: Liquids are miscible or immiscible and chemically they are colloids where both phases are liquids. The particle or droplet size is very large, then it is more likely dispersion or suspension, otherwise it is likely to be an emulsion or a solution.

LIQUID + GAS: Liquid in gas creates a visible mass, as the small particles of liquid have greater surface area, detracting the light. Fog is a natural phenomena considered as a low-lying cloud. Aerosols have liquids in the form of solutions, suspensions, emulsions, and semisolid preparations. Aerosols use propellants of two types: Liquefied-gases and compressed-gases.


Aerosol cans > Wikipedia image by http://streetflies.org/stue

GAS + SOLID: A suspension of liquid droplets or fine solid particles in a gas is called an aerosol or particulate. In the atmosphere these consist of fine dust and soot particles, sea salt, biogenic and volcanogenic sulfates, nitrates, and cloud droplets. Gas entrained, solids create solid-foams, here the volume of gas is large, with thin films of liquid or solid separating the regions of gas. Solid-foams have two forms: Closed cell-foams, the gas is trapped inside pockets of solid material, and in Open-cell foams the gas pockets connect with each other. Open or continuous cell forms of pliable walls are compressible due to freedom for air to move around.


Aerogel > Wikipedia image from NASA

 GAS + LIQUID Foams and froths are colloidal systems, where the gas form bubbles in a liquid medium. Liquid foams are made long lasting by addition or presence of a stabilizer or surfactant. Proteins (eggs, oils, gums) are used as foaming agents. Carbon dioxide dissolved in water is used in aerated drinks and firefighting systems. Foaming is not always a desirable condition such as in lubricating oils. Typically air releasing agents or conditions reduce the foaming. Aerogel is a synthetic porous ultra-light material (98.2% air) that is derived from a gel by replacing liquid with air. The result is a solid with extremely low density and low thermal conductivity. It is known as frozen smoke, solid smoke, solid air, or blue smoke.


Liquefied Petroleum gas is a mix of Propane and Butane with a powerful odourant the Ethanol  > Wikipedia image by Krish Dulal

GAS + GAS: Gases have particles with vast separation in comparison to liquids and solids. This separation usually makes a colourless gas invisible, and offers greater scope for mixing. Mixtures of gases, such as the atmosphere, are called solutions. Gas mixtures are used in a brewery for sparging or purging, that is to remove a (harmful) gas, and for blanketing or inerting to fill up the residual volume with a benign mix. Anesthesia and diving gear have gas mixing facilities in addition to adding water vapour.



Post 572by Gautam Shah


A domain is a very ambivalent term. It is a sphere, area, orbit, field, arena, demesne, land region, or realm. Domains have two obvious features: 1 people who create and command it and, 2 features that indicate the effective extent. A domain could also be an abstract effect, an idea of a space, exploited to sustain the myth of a place. The domain as abstract effectuality is circumstantial, a metaphysical, metaphorical or virtual entity.


Fortified domain –Carcassonne Castle Wikipedia image by Petitemontagnedujura

Physical domains are territorial domains. People occupy lands naturally, forcefully or notionally and distinguish it as domain by personalization of the place. Lands have defining barriers or edges that define the effective extent of the domain. Domains, have features that highlight their size, character, activity, identity, distinctiveness, exclusivity, knowledge, effectivity, ownership, rights, and conformity

Metaphysical domains operate without any dependence on a territorial form. Free Mason Society, Veggies (Vegetarians), Cults (Hare Rama Hare Krishna), Religions, are such metaphysical domains.


Initiation of an apprentice into Free Mason around 1800 >> Wikipedia image

Metaphorical domains have a founding representation or notion. All acts and beliefs, confirming or extending the existence, are acts of participation in commanding the domain. Metaphoric domains are relevant to only a particular class of occupants. Others are unaware of it, or intentionally ignore it. Graphics, symbols, signage, languages, codes, gestures (body language), forms, proportions, colours, expressions, etc. are some of the allegorical presences. Art movements, fashion styles, literary movements create metaphoric domains. Some spatial features and environmental conditions often occur in concert, and so presence of one, metaphorically triggers the other. Historical monuments, places of reverence (temples, ashrams), and memorials have such eminence. Nightclubs, amusement parks, exhibitions, public buildings like airports, also have abstracted elements.


What began as a metaphysical domain entity is now a landed domain… but soon may revert to metaphysical state > Wikipedia image by Austin McKinley

Virtual domains come into being through a wider affirmation of a concept. The governance is through the adherence and advantage out of it. Internet communities like World Wide Web (WWW), G+, Face Book, Tweeter or Blogs are examples of such realms. These are not tied to any geographical region or political power. ISO Quality Management System per 900x is also such a domain. These domains have multiplicity of participation, and as the connections are dynamic, the domain seems virtual.


Social Domain > Chichicastenango Market Guatemala Wikipedia image by Chmouel Boudjnah en wikipedia

Convergence of Domains occurs as all types of domains coexist in a contagious, overlapping or merged environment. They derive their functional efficiency through coexistence and dependence. It is not possible to separate out atmospheric strata from one another. Similarly social domains represent areas for specific behaviour, but are not territorial. Social interactions flourish consistently in certain types of spaces depending on the number of participants, their reach to each other, the means of communication and recognition. These spaces qualitatively contrast with ‘non-social spaces’.


Issac Oliver’s allegorical painting (1590-95) Contrasting virtuous and licentious dress behaviour >> Wikipedia image

Domains also occur as an antithesis, a contrasting element, to the real or notional (virtual reality) entity. If one exists (even if notionally) the other manifests, in a kind of parallelism. Heaven contrasts with the real world, and also has an antithesis as hell. If lands are solid then skies are ethereal.


Neighbourhood as a domain >> Wikipedia image by Challengethelimits

Physical domains have well-defined edges, and so a space with supportive environment. The space is further enriched by including facilities for environmental control and amenities for conducting the tasks. The manageable space is within the limits of human cognition, inside the ambit of nominal physiological capacities, and the extendable reach capacities (through devices). Such domains become very strongly defined space for living or behavioural setting. Such domains have a centric or eccentric form, but receding power as one move away from its core, and at some point other influences diminish its power. Rulers or masters of such domains do not like such infinite receding effects, so rather create barricades or boundaries.

Berlin, III. Weltfestspiele

Stalin cult in E Berlin > Image Attribution: Bundesarchiv, Bild 183-11500-0994 / Martin / CC-BY-SA 3.0

Metaphysical domains occur when there is a tacit understanding among the believers as to what acts are for or against the survival of the domain. The domain persists, depending on the number of believers or followers, and their dedication for the cause. Such influences can also be a legacy. Metaphysical domains show a receding zone of effectuality as the staunch believer or perpetrator of the cult occupy the centre. A vigorously active metaphysical domain projects an entity that is reliable, secure, predictable, proven, acceptable to many. A metaphysical domain does not require a terrain location for identity, however, participants at some stage move to a terrain-based identity, as it provides stability. In this sense the physical and the metaphysical domains converge.


Beatles cult >> Wikipedia image

For a metaphysical domain, areas distancing occur both in time and space. But it is sought to be re-strengthened, by physical means controlling the dynamism (variability) of the environment in the peripheral zones, by suitable space characteristics such as size, shape scale, the quality of barriers, illumination, sound reverberation, axis, orientation, etc. For stage performances the actors use large garments, extensive gestures and loud delivery of dialogues, so that last person becomes part of the show. The weak or receding areas of a metaphysical domain can also be strengthened by use of metaphors. The weak areas are intentionally populated by ‘hard-core’ believers, so that their confirmative behaviour is emulated by lesser believers. Political meets have ‘back seat boys’ (rabble-rousers) whose over enthusiastic behaviour arouses the mood.


Air traffic controller over an air space domain

Metaphoric domains occupy no physical estate, and so are economical and efficient. The regulations are by acceptance and realization that confirmation or participation is advantageous. In spite of the overwhelming fear that it may penetrate into privacy and intimacy domains of social life, such domains offer great scope for expression and communication. The culture of metaphoric domains is now replacing the nominal means of cognition and behavioural responses. It replaces the reality so completely that one often forgets what the reality is, was, or could be. This happens when metaphors have several layers of conversions.


Vsat at Salaga Ghana >> Wikipedia image by IICD http://www.iicd.org/photos

Domains remain primarily a territory or a space to live. Domains become metaphysical as a behavioural setting, and for responses to the environment and others (beings) it serves a metaphorical purpose. A physical domain is beset with too much political interference, a metaphysical one may not be a democratic one, but there is a selfish interest in confirmation of a metaphoric entity.


This post forms 4th of the Sixteen part of Lecture series on Behaviour in Space that I will be offering for the spring semester starting Jan 2016 (to mid April2016) at School of Interior Design, Faculty of Design, CEPT University, Ahmedabad, India.


Post 571by Gautam Shah


Metals parts need surface treatments and cleaning for decoration, reflectivity (shine), dulling (removal of gloss), better hardness, surface integrity, prevention of corrosion and in preparation for the next treatment. Metal components get both organic and inorganic substances deposited from various lubricating oils, corroding environments and substances, and deposits from hard water etc. Metal surfaces need cleaning for removal of residual products from earlier processing, weathering, depositions during storage and transport and environmental contaminations. A cleaned metal is comparatively more active, and so may need, immediate next treatment, to prevent corrosion and contamination. So metal surfaces are often receive simultaneous processes of cleaning, surface activation and protection.

Metal surfaces needs to be smoothed, scrubbed or scoured to receive next set of treatments. Cleaning processes are employed to discharge electrical ions from the component. Cleaning processes are designed to serve several purposes, such as cleaning, scoring and protective coating. Cleaning occurs at a raw material stage, product formation stage, in preparation to other finishes, or just prior to a marketable finish. But there are two distinct stages, at manufacturing plant and on-site applications.


Center-less grinding  Wikipedia image by Wizard191 

Mechanical cleaning use force of air or water jet and sonar waves to remove partially attached particles. The process may include fine particles like sand, silica, metal grit etc. to blast the surface for the same purpose.

Alkali cleaning is typically done with caustic soda (NaOH) which removes all polar substances such as fats and oils. The vegetable and animal oils are converted to glycerol and soap, and the petroleum-based oils and grease are emulsified.

Acid cleaning, like alkali removes ionic deposits from the metal surface. Depending on the secondary products like salts determine the quality of acid to be used. Pickling process removes oxides from the surface by a dissolving liquid. For steel, a warm dilute sulphuric acid, and in some cases hydrochloric acid, hot or at normal temperature, is used. However, for some alloy steels nitric acid, is needed. Acid and alkali both processes require post treatment ph. balancing rinse or treatment.

Solvent cleaning: the articles are washed with a petroleum solvent or undergo cleaning (de-greasing) by vapour, in which a solvent such as tri-or tetra chloroethylene is heated in a closed system, and its vapours are condensed on the metal surface.

Emulsion cleaning: the metal parts are immersed in a warm mixture of kerosene, a wetting agent, and an alkaline solution.

Electrolytic cleaning: the articles are immersed in an alkaline solution and a direct current is passed between them and the other electrode which is usually steel.

Ultrasonic cleaning is used for blind holes or gears packed with soils etc. Small particles embedded in crevices get detached due to ultrasonic waves.

Plasma treatments bombard a surface with electron ions to break the surface level chemical bonds and change the chemical composition of the surface. Plasma treatments may also remove variety of material types such as paints, polymers, glass and ceramics.


Statue of Perseus Piazza della Signoria Florence After cleaning Image by Jrousso at Wikipedia En

Metal cleaning Tools and Techniques

The metal products are small items like nails, rivets, long rolled sections, drawn items like wires, woven items like lattices, entwined items like ropes and barbed fencing, hollow pipes and tubes, or solid castings. Other products include assemblies like automobile bodies, boxes, cages, machine housings and structures like a truss. Metal components are single or multi-metal items, composites with polymers, ceramics, etc. Art restorers have to deal metal objects of unknown composition and ageing, coated with natural or applied substances. Art restorations require reversible processes, so if a treatment is found unviable it can be fully reverted. Metal products in continuous line productions are moved through several sets of electrodes, which, submerged in a cleaning liquid, electrolytically generate hydrogen gas at the steel surface for lifting residues off the material.


Sand-blasting Wikipedia image by National Institute for occupational safety and health NIOSH USA

Hard substances like metal nodules or slags are removed by abrasion or high pressure air or water jet. Soft materials like soil etc. are removed by brushing. Brushing may be carried out dry or wet and with scrubbing and scourager agents. Brushes with natural hair, synthetic fiber, metal fibres and wires are used. Abrasive materials like A Carborundum, sand grit, metal particles etc. are blasted on the surface to clean up the surface. In some instances like manufacturing of nails, abrasive materials rotated in ball mills with nails, to achieve high polish. Ultrasonic sound waves are also used to remove particles.