Wednesday, September 25, 2013

Assessment of Projects


Project assessment requires some degree of quantity determination in numbers, lengths, area, volume, weight, etc. Secondary assessment occurs through comparisons (evaluation) using different factors (‘yardsticks’ or datums). There are two classes of secondary assessments, monetary and non-monetary.

  • Monetary assessments are in terms of the COST (contribution for purchase or acquisition), or the (monetary) VALUE (probable increase or decrease to the cost, or attached sentiments) of an item, or its unitized section.
  • Non-monetary assessments are based on factors like: energy efficiency, loads, stability, consumables, upkeep, time schedules, productivity, risks probability, man power requirements, length, area or volume spreads, growth rates, change rates, ecological concerns, social relevance, legal implications, etc.

Projects are assessed frequently through their period of conception, design, execution and later during operations. In each event, the perceptions, level of accuracy, means of assessment, format of presentation,  and agencies are different. Projects reveal their varied facets, when appraised in different context.

The purposes for assessment of projects include: solving problems, making decisions, highlighting or projecting certain details, supporting or confirming facts, procuring grants, loans, subsidies, and payments like execution costs, rents, lease charges, taxes, etc. These purposes also determine the means and methods of assessment and also the form of final presentation (reportage).

In a design practice an estimate serves diverse purposes, such as:

  • to find out, if there are any costs over runs in a project.
  • to estimate intermediate and final payments to other professionals, contractors, suppliers, etc.
  • to estimate the total costs of executed work, or non executed work, especially when changes in the terms of contract / contractor, or rates are contemplated.
  • to accommodate changes in design, materials, installation techniques etc. due to availability of newer or cheaper options, or additional expenditure with higher allotment of resources.
  • to determine the incidence of tax that is payable as per the government‘s schedule.

QUANTITY ESTIMATING

It is generally experienced that certain form characteristics, dimensions (widths, depths etc.), etc. of parts and components remain constant not only through a project, but across projects of similar nature. Such constants are recognized and minor variables are leveled out within certain dimensional ranges. Dimensional ranges become effective in modular dimensions and through the methods of taking measurements. (See section on Modules of measurements and Modes of measurements). Modest qualitative differences are evened out through flexible and wider rang of specifications.

Quantity estimates form the prime database on which monetary estimate is scheduled. Quantity estimates help us compound simple measures like lengths, widths, heights, weights, numbers, etc. into quantities with fewer variables. Typically a volumetric quantity is more inclusive than linear or surface quantity. Similarly a numerical estimate far more comprehensive than even volumetric estimate.

There could be several levels of conversions before a quantity estimate becomes relevant. One of the most important conversion is through  monetary rating. Such conversions are carried out by many different agencies, without the author or the originator of the quantity estimate being aware of it, or being informed about it.


MONETARY ESTIMATES


Monetary estimates result out of a process called costing. Costing or cost finding is done for item as deliverable by a single agency, or for its parts, which have market equivalents, and so definite prices. However, where parts have no readily available market equivalents, these are evaluated for the cost of their constituent raw materials, labour and other inputs required for the assembly or construction.

Monetary estimates are based on items or jobs which no matter how complex are, consist of only few elemental parts, or very simple tasks. The elemental parts and tasks are usually comparable to many others used in different items or situations. Elemental parts, though similar in form and constitution, acquire a unique personality depending on the position of the component in the whole, nature of use, method of installation or erection and time schedule of installation.

In a monetary estimate parts of different types are categorized on the basis of external factors like guarantee mechanism, life span, utility, depreciation, finance, cost, return, energy consumption, waste output, hazard, ecological value, replacement schedule, etc.


NON MONETARY ESTIMATES

Non monetary estimates, follow a process called VALUATION. The valuation or value providing creates a basis for judgement of an item. The value may be real and may match the monetary estimate of the item. The value could be a hypothetical one based on a perceived use, commonness or exclusivity, observed affectation, future cost of acquisition or disposal, etc.

Non monetary evaluations help define projects from many different aspects for which monetary costs are  available. Yet, appropriateness and success of a design depends substantially on decisions made through such evaluations.

Non monetary evaluations are like:
  • Average space provided to a clerk, average area per resident in a hostel, proportion of area between rooms and a corridor, proportion of usable vs. service areas, energy consumption per user, load per bearing area, garbage output per resident, noise level per vehicle, water consumption per unit, etc.


ESTIMATE SCHEDULES

Estimate schedules represents a comprehensive reportage of the entire exercise of cost finding and / or value providing. The estimate schedule also presents the rationale, means, methods of taking measurements, manipulations done with the information, and presumptions made for thinning out the data.

  • Format of an estimate schedule depends on by whom, and for what purpose these are accessed. A customary format is evolved by the design organization to suit its own nature of practice and needs. For commercial use like tenders or quotations etc. a style confirming to local market is required. For Government and corporate entities, designers have to adjust the format of estimate schedule to their accounting procedures requirements.

  • Estimate reports once created are used by many different people, and for nominally never perceived uses. A person preparing the estimate must foresee that, someone else in another time span will deal with the estimate, not only to interpret, but also to revise it.

  • The format of presentation, logic and mode of documentation should allow easy revisions. All the contextual information and their sources must be properly recorded. Procedures for accommodating various parameters like: fitment sizes, tolerances, mode of measurements, modules of measurements, rounding off, average, means, etc. should be of standard type, or well explained.

  • Accuracy of an estimate depends on how well the job has been conceived and detailed. Estimates that create liabilities due to their ability to cause secondary changes elsewhere (such as: item selection or elimination), or have hazardous consequences, are prepared with due care. Budget  estimates prepared, before or during the design and execution stages are approximate only, because the cost base is presumed, or of a current date. By the time actual execution occurs, the costs may go up or down, or the components may get altered. Whereas, Historic estimates prepared after the item has been executed and paid for, are very exact, as the cost base is real and accomplished one.

  • Estimate Reports become part of finance related procedures of the client. Typically financial institutions would like to sanction a loan on things that are physical, fixed, long lasting and with resale value. As a result, soft furnishings, polishing, painting and such other expenditures are not favoured for borrowing. A designer and the client (or the financial expert) together can, to an extent, redefine some of the items, or divide and regroup the items so that these can be classified as worthy of an appropriate category of disbursement, expenditure or depreciation. By re-framing the specifications, such items can be made integral part of the hard furnishings.

  • Exposure of estimate reports: An estimate schedule is a very sensitive document.   Its exposure to outsiders, including the client, automatically makes it an open document with lot of liabilities. A premature  exposure conveys a hidden guarantee, that items with such specifications will cost so much. A client may perceive the provisional estimate details (of a mid project appraisal, etc.) as a promise. Where it is necessary to expose an estimate report prematurely, it should be conditional. All data, specifications, assumptions, forming the estimate base must be preserved.

  • Estimates reports provided to outside agencies, though prepared for their specific needs, must not create undue liability for the designer. Government and other agencies demand Estimate Reports for sanctioning grants, loans, subsidies, etc. But due to large scale design + build practice prevalent in interior design, more often than not, estimate reports are interpreted to be an advance or pro-forma-invoice for supply of goods or services, and money is accordingly issued to the author of report (the designer), rather than to the contractor of the scheme. This could involve a designer into a huge tax liability.
  • To avoid such a situation design professionals in their estimate reports, must clearly state: "this  estimate report presented by the interior designer, is a designer’s estimate and not a pro-forma or advanced invoice, or a promise to supply, or arrange to supply the goods, or services, that are implicit in the  report.”

Estimate schedules are of two types representing the stage of the project. 

    1    Budgetary estimates are prepared at the beginning or during the work.
    2    Historic estimates are compiled after the completion of the work.

Budgetary estimates are prepared to determine the likely cost of execution. It helps in planning of  resources, to search options, to check quotations, to control likely cost over runs, to determine the professional services bill amounts for % fees.

Pre execution or budgetary estimates are made with certain presumptions. Such estimates remain variable, because for every change in parameters like, the cost of input materials, labour etc. the estimates need revision.

Budgetary estimate, as a document are designed to be revisable. The fluidity lasts till the item is executed. Once the item is born, the budgetary estimate document if adequately updated, becomes static, a historic estimate.

Budgetary estimates are usually made by the people involved in the design and execution of the project, because they have all the data resources.

Preliminary  estimates help in feasibility check up, primary budgeting, funds planning, in fixing the extent of a job, and stages of strategic and tactical actions.

Clients on their own prepare or order a cost estimate, often, even before retaining a design professional. Such estimate projections prepared by a financial or project consultant at times contain lot of technical terms of finance, and a good design professional must have the proficiency to understand the terms, and if necessary comment upon such data.

Mid-project estimates are carried out, as a design takes a concrete shape with  dimensions and details. These estimates help in final selection of materials, finishes, procedures, details, etc. Several such in-house evaluations are carried out as the design progresses. A client may be exposed to selective sections of such evaluation exercises, to increase the awareness of the design process, to solicit additional information, and get approval of certain design decisions.  

 Tender or Contract estimates are very exact, requiring equally perfect drawings, details and specifications. Tender estimates are often used to verify bills for work. The structure of such estimates is controlled by factors, such as: nature of an item, schedules and sequences of execution, contract system, supervision  system and agency, modules of measurements, modes of measurements, mode of billing and mode of payment.
Historic estimates, are made, to determine the actual expenditure incurred on a project. It also helps in assessing the absolute value addition to the wealth, investigate conditions that caused cost over or under runs, to determine the set-off or depreciation amounts, to set insurance cover charges, to fix operations or servicing costs, etc..

Historic cost estimates are prepared on the basis of accomplished facts, soon after the birth of a product. Historic cost estimates are very realistic, unalterable  static documents, and have an archival value.

Historic estimates, may also be carried out by third parties, or people not necessarily involved with design or execution processes.

Assessment of Projects  --from series Interior Design Practice and Office Management -II


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Thursday, September 19, 2013

BUILDING as a SYSTEM

Building as a System  > from series Interior Components and Systems

Building as a System /Building : A system for inhabitation / Categories of Building Systems /How Building Systems emerge /Building User and the Environment


1.0.0 BUILDING AS A SYSTEM

A building is a very complex entity made up of many parts, components and systems. Some Parts of the building come together to form a Component. Parts and Components function in unison to form a System. A system has twofold identity: a unique personality of what it does, and a coherent character of how it carries out its functions. The ‘first identity makes a system substantially self-sufficient’, but the ‘second identity makes it a participant of a larger system’.

A building is a Man-made system compared to many Natural systems (such as weather, ecological, solar etc.). It is a Physical system unlike many ‘Conceptual’ or Nonphysical systems (such as information, taxation etc.).

Buildings are physical  entities composed of many elemental units. Buildings have systems of form and size, which render subsystems like scaling, modulation, proportion, hierarchy, patterns, etc. These subsystems in reference to the Universe provide orientation, siting, location, etc., and in association of the User offer left-right positioning, sense of vertical and equilibrium, anthropometric functions and sensorial values.
A building can be perceived as a very large and complex system consisting of many different types of systems and subsystems. The systems are customarily categorised in terms of what they do: such as Structural, Architectural, Interior, Electrical, Mechanical, Air-conditioning etc. Some of these are fairly independent or mutually less related systems, and so can be installed, replaced or removed without many of the consequential effects. However, other systems have very intense coherence, and so once installed cannot be easily removed or replaced without affecting other systems.

Buildings have emulated the biological system of live beings -Biometrics. Buildings are designed with not only built-in capacities or reserves, but designed to be responsive, through strategical planning and synergetic devices. Buildings consume energy to be a functional system, and as consequence of it, generate byproducts.


1.0.1    BUILDING : A SYSTEM FOR INHABITATION

A building can be defined as a system for inhabitation. The building or the shell can be built exclusively out of structural systems, but for inhabitation many other subsystems must be incorporated into it. These incorporated subsystems have no or a very little structural role, though may depend on the structure to be operative. All subsystems of the buildings cannot be type-cast neatly as structural versus non-structural entities. There are several reasons for this. Structural and Non-structural systems swap their roles under specific conditions. For example a door or a window frame of opening systems may carry some loads in an earthquake like a situation. Inversely, a structural system may become latent or redundant, as for example a retaining wall of a swimming pool filled in on both sides may not be required to act as a retaining structure. In both types of swapping of roles, the changeover may be temporary, permanent, reversible or non-reversible.

1.0.2    CATEGORIES OF BUILDING SYSTEMS

STRUCTURAL SYSTEMS: A structural system by its  intrinsic  nature, composition, position, or arrangement, provides a whole that stays stable, in equilibrium, or constant (yet may be mobile like a ship, spacecraft etc.). The structural subsystems of a building system must exist in the required location or be available at the required moment and duration to achieve the distinctive constancy. The stability of a building is disturbed, when the structural subsystems are repositioned or removed. Structural systems of the building seem to be well integrated, because by being together they achieve constancy, which is fundamental to a structure’s being.

NON STRUCTURAL SYSTEMS: Non-structural systems of a building apparently  have no role to play in the constancy of the building. Subsystems within a building that do not affect the constancy of a building may be called non-structural systems (e.g. partition walls, doors, windows, finishes, etc.). Non-structural systems though useless in structural sense, are not totally dispensable.  Many non-structural systems  protect the structural elements, like plaster, walls, claddings etc. Some non-structural systems achieve their own stability by depending on the structural systems, e.g. a stretched net or a sail. Non-structural systems need not be integrated with the structure so are replaceable or relocatable.


TYPES OF NON STRUCTURAL SYSTEMS used in a building:

  • Protective systems: that cover the  structural systems and  non structural systems, e.g. plasters, waterproofing, roofing.
  • Filler systems: fill up the gaps or spaces between structural subsystems, e.g. non load-bearing walls, joints.
  • Independent systems are complete systems by themselves that independently provide peculiar functionality, e.g. air conditioning, illumination, communication.

CONSIDERATIONS FOR A BUILDING AS A COMPOSITE SYSTEM:
  • Identity : elemental units such as parts, components and subsystems.
  • Location, position, and  orientation of the elemental units within the system (the building).
  • Schedules and conditions of occurrence or being relevant for the elemental units within the system (the building).
  • Nature of interrelationships between the elemental units, such as: synergy,  coordinated behaviour, dependency, autonomy, and also: order,  patterns,  sequence, proportion, modulation system etc. involved.
  • Design compulsions such as minimum standards, codes, laws, regulations.
  • Technological relevance: Materials, specifications, experience, skills that are required.
  • User considerations: anthropometric and ergonomics, safety aspects such as hazards, risk management, sensual qualities, aesthetics.
  • User relevance in terms of novelty, tradition, vogue.
  • Environmental concerns: ecological value, disposal mode.
  • Operational aspects: repair,  maintenance,  replacement, accidental and malicious damage.
  • Social values such as acceptability, relevance, validity.
  • Economics such as value, cost, price.
  • Occupation and Inhabitation factors: life span, adaptability.


1.0.3    HOW BUILDING SYSTEMS EMERGE

Building as system emerges at many levels and modes, some of these are:

  • Invent a novel entity using none or few of the existing subsystems, to replace several existing subsystems.    A window like opening system consists of many sub systems like grills, glass, railing, filters (jalis, nets), awnings, weather sheds, ventilation, safety and security hardware etc., but a comprehensive device can replace all such sub systems. 
  • Improvise important subsystems to substantially transform the physical nature of the main system.  Installing an elevator or air-conditioning system into an old building completely transforms its nature. 
  • Upgrade the working of the system by rationally relocating and time scheduling the various subsystems.
  • Adopt subsystems as offered by others such as: designers, innovators, inventors, vendors, through facilitation and customization.
  • Universalize systems by following standards, codes and protocols. Follow international practices such for Quality -QMS, Environment -EMS, etc.
  • Provide distinct intra connectivity between subsystems through a distinctive network or an ancillary subsystem.
  • Facilitate networking capabilities between systems with a view to achieve a larger system, through provision of nodes, interfaces.
  • Provide for greater integration between physical and non-physical subsystems.


1.0.4    BUILDING, USER AND THE ENVIRONMENT

A building as a complex system is designed to function in an environment and inhabited by a user. A building affects and gets affected by the user and environment. The building’s innumerable systems are permanent, replaceable or up-gradable.

The technological up-gradation of building as a system occurs through:

  • Replacement by an efficient system.
  • Elimination of several sub systems by adoption of a comprehensive system
  • Integration of several systems by spatial rearrangement or rescheduling.
  • Regrouping the systems by their user and environmental relevance or affinities so that systems operate with greater productivity.
  • Greater use of non-physical systems instead of action elements, sensing mechanisms, control elements, decision elements, connecting elements, distancing elements, converters etc. 
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Changes in buildings are:
  • Intentional changes such as: functional, technological upgrading, styling.
  • Circumstantial changes such as: due to ageing, wear and tear of use, over-use, under-use, non use, and mis-use).
  • Environmental changes: some major categories are listed here:

1    User on occupation customises the building by self-help, but changing only the familiar and easily removable subsystems. The user has to hire semi-skilled crafts-persons, or retain specialists or professionals like architects, interior designers, engineers, etc. for altering partially integrated or coordinated subsystems.

2    Building begins to affect the user, through its awe, form,  discipline,  flexibility, unyielding rigidity, historical values, location conditions or setting, economics considerations, perceived stability, and expected life, etc.

3    Environment moulds the building, nominally at a very consistent pace and in a predictable manner. Some changes are of  imperceptible  measures  and  often ignored till the cumulative  effect is  beyond  remedial correction.  The environment also changes the building at an inconsistent rate and unpredictably, so all precautions prove useless.

4    Building impacts the environment in many ways. It causes  changes in the surroundings by its  presence, operations, and ultimately on its demise,  demolition and disposal.  A benign presence is  one  that disturbs  the environment for small time scale and over minor extent, compared to very long lasting and extensive disturbances to the balanced state. A building has nine lives like a cat. A building reincarnates itself in spite of disintegration of many of its sub systems. A building may lose its original form and functional identity, yet continue to be relevant as a shell for a different nature of occupation.


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Sunday, September 15, 2013

COATINGS -Iron age

COATINGS    -Iron age              from series Surface Finishes > Coatings > Iron age

Iron Age is a period that is very broadly defined, in time scale, intensity and geographical extent. But it represents a complete command over the fire, related handling processes and beginning of chemical analysis. In the early phase, it gave a birth to remote handling tools and techniques, like the arrows, spears and other projectiles used for hunting. Fuels, structures for hearths and kilns and vessels were devised to work with fire. These were paralleled with refinement of materials processing technology. A whole range of chemistry was developed through baking of ceramics, forming glass beads and food processing. Reduction of metal from ores and the secondary processes like casting, shaping, forging, alloying, smelting, calcining, etc. provided many other forms of materials. Richly hued and intensely toned colourants or pigments formed part of these discoveries.

  • A distinction is usually made between a pigment, which is insoluble in the vehicle (resulting in a suspension), and a dye, which either is itself a liquid or is soluble in its vehicle (resulting in a solution). A colourant can be both a pigment and a dye depending on the vehicle it is used in. In some cases, a pigment can be manufactured from a dye by precipitating a soluble dye with a metallic salt. The resulting pigment is called a lake pigment.

Rich colourants were very important for human body colouration, alive or dead. In the second line were the processes for colouring of ceramics through the application of slip-glazing, and colouring for personalization of tools and implements. Origin of the coatings is attributed to the ritualistic paintings in caves. However, caves became less important for rituals as the abodes were now built in non-hilly farm lands.

Agriculture and husbandry provided a greater range of oils and liquids to bind the pigments. Pigments and white powders were now more concentrated and ground much finer. Human body decorations had now brilliant colours. Ceramic colouring was mysterious as completely different tones developed on firing. Tools and implements were made from made from wood, plant products like fibers and grasses, horns, bones, hides, and metals. These were decorated for personalization (ownership branding) and for endowing magical powers. Decorations or patterning required variegated colours. Patterns had finer zones accomplished with other craft processes such as texturing and engravings. Colours were rubbed to impregnate the surface deeper and then rubbed over to remove or dilute the over-laying materials, thus creating differentiated foreground-backgrounds.

In the later part of Iron age formal buildings were of masonry work. The crafted patterns and the architectural elements were coloured. Wall murals with greater details and intensive spreads, were created mostly over the stone, mud or mud-bricks surfaces. For mural paintings the walls were rendered by a prime coat of daubing, plaster or gesso work. The daubing used plastic clays with fibrous additives, slaked lime, volcanic ash (pozzolana). The plasters were made with slaked lime, gypsum, etc. but finished to a smooth surface or even textured finely. Gesso work over the wall consisted of white or lighter colour mineral powder mixed with natural gums, plant’s latex like juices, eggs whites, urine and milk, as very thin surfacing. Lime was best cementing material. Clays of high plasticity were mixed with pigments and used for substrate creation (a primer and leveling coat). To achieve high opacity and colour saturation, several such layers were applied.

  • Egypt wall art work: Stone surfaces were plastered with lime or mud, and topped with smooth Gesso, that is a mixture of chalk, gypsum and pigment with a binder like natural gum, white of eggs. Fine finished lime-stones were coated with lime wash before painting. Pigments were mostly oxides. It is also clear that paint was applied on a dry surface unlike as in Frescos where it was applied on wet plaster. After painting, a varnish or resin (plant exudate gum dissolved in hot oil or alcohol) was applied as a protective coat.
  • The Egyptians used colours for expressions then realistic presentations: Such as Red skin meant youth and vigour. Yellow expressed the woman or ordinary citizen, Blue and gold was reserved for higher persons or immortals, and Black was for royals.

Many other objects, made of wood, ceramics, stones, and metals were also painted or decorated. These objects had surfaces with poor holding (binding to the substrate). Oils and waxes were used to mix pigment colours or absorbent dyes were used. Oils (plant or animal origin) have a tendency to remain wet (non drying) for a long time and collect dust on aging. Oil mediums though superior in fixing and longer lasting, yellowed with age, and destroyed due to fungus and algae. The chemical modification or additives for oils were available around 10th C. AD.

Papyrus and Fabrics of cotton, jute, flex, linen, hemp, etc. were extensively used. These were printed, painted and stamped with pigments or coloured (yellow, blue and red) with dyes.

  • It is believed that word Chemistry is derived from the word khemeia, which relates to the Greek word khumos, (literally meaning juice of plant or art of extracting the juice -or extracting liquid metal from rocks). The art of khemeia is the art of metallurgy, which was obscured in unexplained processes. In Arabic, khemeia became al-kimiya (Farsi, Gujarati Hindi Kimiyagiri=one who knows the formulation). It was adopted as alchemy.

Next few BLOG posts in this series will be :

THE CRAFT OF WALL PAINTING
THE ART OF OIL PAINTING
WATER COLOURS AS ART MATERIALS
THE MODERN TECHNOLOGY OF COATINGS
COATINGS: FILM FORMING SUBSTANCE
COATINGS: COLOURANTS AND EXTENDERS
COATINGS: SOLVENTS, THINNERS AND DILUTANTS
CLEAR AND COLOURED COATINGS
ARCHITECTURAL COATINGS
INDUSTRIAL COATINGS
SPECIALTY COATINGS
SOLVENT FREE COATINGS
COATING AS A MATERIAL DEPOSITION TECHNOLOGY



Saturday, September 7, 2013

PRIMITIVE COATINGS Surfaces, Materials and Techniques



PRIMITIVE COATINGS    Surfaces, Materials and Techniques     article - II in series Coatings

Coatings have been used for coating and decorating many objects and surfaces for the past 60000 years. ‘Coatings’ were used to add colour, add a protective layer, ‘plaster’ a surface, impart a pattern or an identity signage. The coatings materials were mostly of natural origin such as available off the ground, or from animals and plants. The act of coating was intentional, done with a sure purpose. But it had a wondrous effect that gave a new purpose to the artefact. Coatings’ techniques used for painting became a magic media to express what spoken language could not do.

Objects and surfaces to be coated:


A primitive person, for the supposedly unencumbered life, had many objects that could receive coatings. These objects had natural or formed shapes and surfaces. The surfaces had different porosities, textures, base-colours and patterns (grains, patches, stains, etc.). The objects were hides, skins, bones, teeth, stones-rocks, ‘precious stones’, sea shells, dry leaves, plant fibers, wood, raw and baked clay products, and of course own body parts such as hair, skin, nails, teeth, etc. Some of the surfaces such as the hides were cleaned and shaved by heavy rubbing. Bones were ground to remove the sheen and make surface slightly rough and absorbent. Stones and woods were polished or scrapped. Raw and baked clay products were re-fired after coating. Leaves were rolled, pressed and dehydrated at the green stage by burying in layers of ash or sand.
 
Coating Materials:

Coating materials of the primitive age are still being used in many situations and so continue to be relevant. Blood is perhaps the earliest colourant. It is a liquid of rich colour, representing the vibrancy of life and the metaphorical power over the kill. However, blood has very weak colour integrity and it is biologically highly degradable material. Wood coal is a dry colourant, easy to handle. It requires a textured base for ‘rubbing-in’ or a binding liquid to form an applicable paste. Carbon (Lamp) Black -a deposition collected over burning fat or oil, is much better due to oil content. Whites were procured from metallic oxides and carbonates. Lime is most common everywhere. Iron Oxides are equally common, and have many different hues (such as yellow, brown, red and black). Oxides are very stable and ‘deep’ (high saturation) colours.

In this palette the notable absence was of Green and Blue colours. Brilliant Red that could represent the fresh blood, and Pink of the meat were also absent. Absentee colours were sought from plants, flowers and fruits. These were Yellows, Orange, Greens, Mauve and Purple. However, plants, seed and fruit juices were of low opacity (transparent), sun light fading and biodegradable colours.

Binding materials and techniques:

The colour palette was of mostly of dry powders or soft rocks. These had poor binding to the substrate. Liquid juices were absorbed into the surface. By heavy rubbing the colour pigments got trapped in the micro cavities of the surface. Some form of binding material or technology was needed. Water was used as a carrier agent, but its binding was only temporary. Plant oils, mutton fats, fish oils, etc. were used to fix colours. However these oily substances were ‘non-drying’ and remained wet for a long time. The wet surface attracted dust and trapped insects. The oily substances deteriorated and on oxidation turned dark in colour.

Proteins-based materials like blood, eggs, milk, urine, starches were also used as binding materials. Plant and insect exudates or natural gums had binding properties but were highly hygroscopic (affinity with water) materials. Plant milks or latexes, like materials, were also used. Wax was used to mix with pigments and as a protective layer. Wax and Natural Creosote were used to protect wood and leather surfaces.

Slaked lime and pozzolana (volcanic) ash, were two alkaline materials that had binding properties. However, lime when mixed with a colourant imparted a white shade creating a ‘pale’ effect. Pozzolana had darker colour so made the colourant several shades darker. Clays of various mineral contents were also used to bind the pigments. Plastering and daubing were frequently used to prepare a better surface for a wall painting.

Some mechanical processes were used to help coating application. These were surface rubbing, hammering, scrapping and shaving (for leather surfaces), heat burnishing and surface sintering.
 
Primitive binding materials can be categorized in several ways:
  • Natural binding properties versus the water wettable/ reducible materials, 
  • Drying versus non drying,
  • Water wettable or hygroscopic versus water resistant materials.

With vast array of surfaces to be coated and availability of wide variety of colourants led to experimentation. By the time of stone age refining and upgrading of colourants was achieved. Surface finishing techniques were much refined.

Three outstanding technologies were devised.

1  It was application of plaster with and without colourants,
2  It was pigment refining, sintering and grinding,
3  It was colouring ceramics before firing to create a permanent colours.

  • The earliest known cave paintings date from about 32,000 BC. Lascaux, an underground cave (15000 to 9000 B.C.), located in south-western France, has walls and ceilings, decorated with some 1,500 engravings and about 600 paintings in shades of yellow, red, brown, and black. The sheer scale of the paintings suggests that ladders and scaffolding must have been used. Charcoal, lamps, spear points, pigments, and engraving tools were discovered on the floor of the cave. When the cave was discovered, the paintings were in a very fine state of preservation, due to the stable levels of moisture and temperature within the cave, providing an ideal environment for the preservation of pigments over thousands of years. However soon after being opened to the public, the paintings began to deteriorate, colours beginning to fade, and a green fungus  grew over the pigments.

  • The pigments of cave paintings probably have been preserved by a natural  process of rainwater seeping through the limestone rocks to produce saturated bicarbonate. The colours were rubbed across rock walls and ceilings with sharpened solid lumps of the natural earths. Outlines were drawn with black sticks of wood charcoal. The discovery of mixing dishes suggests that liquid pigment mixed with fat was also used and smeared with the hand. The subtle tonal gradations of colour on animals painted in the Altamira and Lascaux caves appear to have been dabbed in two stages with fur pads, natural variations on the rock surface were exploited to create the effects of volume. Feathers and frayed twigs may have been used in painting manes and tails.

The Coating Application Processes:

The simplest way of marking cave walls was to make finger-nail traces in the soft layer of clay covering the rock. Lime stone walls were engraved and filled in with iron oxide (hematite, or ochre), or the black pigment such as the manganese or charcoal. These materials were usually available locally. Analyses of pigments, reveal the use of extenders (dull or low opacity powders) such as talc or feldspar, to increase the bulk of pigments. The coating also shows traces of animal and plant oils, used for either for binding or as a protective covering. The pigment in paste form was applied with fingers, and also tools like fiber pads, animal-hair brushes or crushed twigs. Lumps of pigments discovered on the floor of caves were perhaps used as crayons, or were grinding onto colour powder. Colours were often sprayed, directly from the mouth or through a tube. A network of ladder, supports and scaffolding was used to reach the ceilings and upper portions of walls. Light was  provided by hearths, or portable burning torches. The coated surfaces were ground to achieve a sheen on the surface or re-coated with protective layer of egg-whites, oils or fats.

The primitive age craft of coating can be summed up as Surface preparation, Application of the coating, Applying tonal variations or shades, and Covering the surface with water protective coat, usually of oils or other transparent materials.




Next Blog post in continuation of this series
Coatings in Iron age

Tuesday, September 3, 2013

COATINGS

INTRODUCTION :COATINGS:

Coatings are thin surfacings. A coating is mainly created through a change in the physical state of a material (change of phase). At application-stage a coating material is in various state or phases such as liquid, solid or vapour, or a combination thereof like: suspension, solution, dispersion, emulsion, thermoplastic compound, thixotropic compound, etc. Coatings, however, once applied ultimately settle down to a heavier phase, usually (but not necessarily) a solid phase.

At an application stage a lower phase helps in many ways:

1.     Easy, uniform and thin level of application.
2.    Better dispersion of costly or rare constituents.
3.     Easy and thorough mixing of constituents such as film forming materials and other additives.
4.     Less energy is required for application.
5.     A controlled rate of deposition through phase conversion.

Coatings are generally capable of forming a film on the relevant surface. However to form a film through coating, the surface may require some modification or treatment. Surface treatments form a very important section of coating technology. Surface treatments are specific for the surface to be coated, and include processes like: cleaning, roughening, smoothening, etching, and also moisture proofing, rust inhibiting, barriers, static arresters, etc. Other surface treatments are designed to facilitate the application or deposition of the surface forming component and its setting or drying.

Coating as a surface finish system has certain advantages. Such as:
  • Coated surfaces can be very extensive because there are no joints (except at junctions where an adjacent coating application is delayed, such as a dried out portion and a fresh coat touch each other or overlap).
  • Coatings are thin surfacing and being malleable and allow post-forming operations (such as bending, shaping etc. of coated metal sheets).
  • Coatings by themselves are a surface finish (unlike an adhered surface finish involving the adhesive and the surface component) so allow creation of thinnest possible applied surface over an object.
  • Coatings allow creation of a multi layered system, where each layer has a distinctive quality.

Coatings are not considered adhered-finishes, because the coating film is formed and bonded through a lower to higher phase conversion process.

Coatings are deposited on objects by many different techniques and in variety of conditions. Common coatings are applied at normal environmental conditions. However, high end coatings require conditions that are usually unavailable at construction sites, such as exact environment and controlled application, drying and handling techniques.

Coating is a thin Surface Finishing Technique. A coating with or without a colourant and other additives is nominally first transformed into a liquid phase (solution, suspension, emulsion, etc.), applied over a surface by using many diverse processes, and then allowed to ‘dry’ out or ‘cured’ to convert into stable or solid state.

Coatings are applied to entities to alter the feel, appearance and other sensorial qualities. Coatings also provide insulation, conductive properties and protection. Coatings have been used for expression that is for art, illustration and decorative effects.

Primarily a  coating consists of a material that is in a liquid state or is convertible into a liquid phase. At least at the application stage most of the coatings are liquid, or brought to a molecularly very active stage of a colloidal system, such as gel, suspension, emulsion, foam, solution, etc. However, complex coatings may be formulated of materials in various colloidal states and possibly these materials are changeable into phases other than liquid.

Generally a coating consists of many different components, such as a film forming substance, colourant, reactive agents, solvents, and additives, etc. In a very complex coating composition such clear-cut distinctions are not apparent, because film forming substances and additives serve purposes beyond their nominal roles.



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