FOOD PREPARATION SYSTEMS – V (Kitchen Fire)

Post 223 – by Gautam Shah

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Fire has been difficult to initiate, maintain, contain, handle and extinguish. A secure fire helps the process of domestication, just as sharing of food with the family was beginning of a home. Fire is a hazard but if controlled can provide warmth, light and security. It needs to be shielded from rain and wind. Fire is a change causing element in every aspect of living.

Hearth in Pompei

Hearth in Pompei Wikipedia Image by Jebulon 

Fire can be sustained mainly with a built form and supply of combustible materials. Fire, however needs several handling technologies, such as:

  • Fuel sizing, storage and charging,
  • Ignition,
  • Aeration methods,
  • Holding tools,
  • Shielding and Insulation,
  • Heat distribution,
  • Emissions, odours and solid residues,
  • Fire enclosures like hearths,
  • Pots and vessels, supports, 10. Fire dousing tools.

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Gold Smelting Egypt

Gold Smelting Egypt

Collection of combustible materials was volumetrically very large, and sometimes even more difficult then procuring the foods. Fire fuels needed size reduction for transport, and storage for an entire season. A housed fire, however, fostered many other activities besides cooking. It was used for illumination, warmth, farm, craft and industrial conversion processes. Many technological innovations were supported by such a large scale need for fire. The main thrust areas were efficient fuels and effective ways of using them. Fuels must be dry, compact, easy to size and store, smoke free and with high thermal efficiency. Effective ways of handling fire included using fire for heat conduction, convection, radiation, latent heat of materials and the residual heat in emissions.

Wall Hearth

Open fires were dangerous and problematic, but men could not do without it. The first efficiency was achieved by arranging the fire inside a walled chamber, the hearth. A hearth allowed controlled rate of combustion, protection from random sparks and limited effects of radiation. The hearth was multi-purpose entity, and allowed use of converted fuels like chopped wood, broken twigs, animals’ excreta cakes, briquetted coals, and liquid fuels like lard, tallow and oils. These fuels had smaller mass, better storage system, and greater heat efficiency.

Free Hearth

Free Hearth

Smoke and soot were problems that were tackled by locating the hearth in appropriate place. Many fire-related lessons were learnt from craft and industrial processes like pottery firing, metal smelting, shaping and forging, farm produce dehydration and baking, sintering of minerals, lamps for illumination, etc. Metal smelting taught how to achieve high temperatures, whereas dehydration and smoking (of meats) helped on how to maintain low temperatures for longer period. First attempts to reduce the temperature involved distancing the pot or food from fire. Hearth design micro improvisations (learnt from ceramics firing) taught how to control air supply to the fire.

Hung pots distancing to control heat

Hung pots distancing to control heat

The local fuels, their quality and quantity, both affected the nature of food recipes. Different forms of direct-radiant, and indirect-reflected, heat applications created processes of simmering, stewing, boiling, smoking, charring, barbecuing, baking, roasting, etc. The hearths began to take different forms depending on the type of fuel available.

Wall Hearth with various forms of Heat input

Wall Hearth with various forms of Heat input

In colder climates the hearth was a warming fireplace. It became part of an alcove or a niche in the wall. The hearths were bulky to retain heat within the mass of body and use their delayed throw back of heat (re-radiation). Cooking procedures were long lasting (Stew-preparations), and dining close to the hearth. In warmer climates hearths were a source of heat and discomfort. Hearths as a result are placed in the corner of a room or outside of it. Hearths are thin bodied and to allow faster cooling after cooking. Cooking procedures involving use of fires are short and requiring lesser intervention. All non fire cooking procedures are conducted elsewhere, away from the hearth. Food preparation activities occur in other parts of the dwelling.

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CREATIVE WRITING -1

Post 222 ⇒   by Gautam Shah 

 

We, express about things, ideas, dreams, experiences and concepts to communicate or record. There are many different modes of expressions: gestures, natural sounds, articulated sounds like utterances, music, written and drawn presentations, modelling, etc. The expression could be very personal with no one else being aware of it, or open for a select few or wide audience.

640px-Madaba_map

Expression is a creative activity, where the present, past or future, all transcend from one to the other. An expression could be a re-enactment of the happening for recollection here and now (Past to present); for recording onto a media, to be accessed in another time, space, context, and by different persons (Present to future); or imagining and establishing bridges to experiences (Future to past).

Mahatma_Gandhi_writing

Most expressions, other than personal recollections are designed for the audience and their capacity to perceive. Expression originators have some innate knowledge about the audience. An expression originator, along with the expression content also provide clues and reinforcements to reach out to the audience.

The expression is meant to secure believers or sympathisers and occasionally even antagonists. On the other side audiences comprehend the information to empathise, seek knowledge, form opinions and gain something from the experiences of the author. Some expressions are perceived and assessed for the presentation modalities, style or format.

As an effective communicator the expression must offer some provocative information, to satisfy, inspire or instigate the audience.

Edinburgh_fringe_royal_mile_street_performance

This is done in several ways. Where subject matter is self-evident, the tendency is to present the components in the order of the sequence of occurrence. This method of presentation, however, sometimes fails to establish a root with the late comers. A reverse strategy is applied where the end or result is presented first, and then the beginning is traced. For written expressions, a person can scan a document, to see if there is any thing of relevance. Presentations start at simpler and universal level, establish a bridge with the audience, and proceed to complex matter, always succeed.

Narration

The expression styles are:

  • Narration: telling a story in time sequence,
  • Description: relating to what you see, hear, taste, feel, and smell,
  • Rhythmic: Using beats, rhymes, repeats, and associations,
  • Process or Recipe: describing a sequence of steps necessary for a process,
  • Definition: illustrating the meaning of certain words, ideas or constructing a concept, ideology or theory,
  • Division and Classification: grouping ideas, objects, or events into categories,
  • Compare, Contrast and Evaluations: finding similarities and/or differences between topics,
  • Analogy and simulation: making a comparison between two topics that initially seem unrelated, Simulation involves using various sensorial effects for reinforcement,
  • Cause and Effect: explaining why something happened, or the influence of one event upon another.

Shans_at_home._With_two_chapters_on_Shan_history_and_literature_(1910)_(14741248406)

The expression style (like detective or crime novels) could be where: 1. Events are constructed leading to revelation of the end, 2. Ends are exposed, followed with the explanation of the process, 3. Process and Leads to the end, are presented alternatively.

Shadow play story telling

All expressions, whether for record or communication, to be effective are focussed to a theme, and everything beyond that is excluded.

All presentations must be simple and clear, with minimum of additional information. For a communication to be successful it must be designed for the audience. A very technical ‘writing’ limits the class of audience, whereas trivial contents though provide a wider audience, are prone to unintended interpretations (de-constructionist).

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PROCESS of CHANGE in BUILDINGS

Post 221 ⇒   by Gautam Shah 

PROCESS of CHANGE in BUILDINGS

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A building exists and flourishes in its circumstantial surroundings and within the environment. These two factors bear upon a building depending on the form, functionality and technological grade. A building exists in the social, political and an economics profile of the locality. The environmental factors are absolute and are fairly consistent, but at micro level these effects are conditioned by the happenings in the immediate vicinity. The surroundings are circumstantial as these affect depending on the use and relevance of a building.

Reichstag after allied bombing of Berlin

Reichstag after allied bombing of Berlin

Life of building is governed by environmental pollution over a location. It strains the parts and components, hastening their failure. It also makes functional efficiency difficult to maintain. Prestigious old buildings in good localities are more likely to be well looked after, than in deteriorating locations.

Contextual setting of a building is considered mainly in terms of its Location and Age, and both change simultaneously. A good building is integral to its space and time. Changes in the contextual settings affect some buildings more, if these are: Intensely located that is subsisting on the site related advantages, highly stylized, acutely dependent on the technology, and endowed with high degree of functionality.

Otr redevelopment vine street A

Otr redevelopment vine street A

Otr redevelopment vine street B

Otr redevelopment vine street B

Location is the external realm of the building. It has two facets: the distance or the extent and the stack holders of the building. A building serves certain terrain or physical depth. When these get enlarged due connectivity by efficient transport services, or the usage is increased, but conversely barriers like railway tracks, canals, closure of roads, or loss of visual identity affects the raison d’être (reason for existence) of the building. Stack holders become insincere for maintenance when the location begins to deteriorate due to economic, social or political problems, and affects the pride or faith in the building.

Age dilutes the connections a building has with the location and the circumstances. A building on aging becomes irrelevant for the original functions and current day technologies. It can, however, still continue to survive, if its structure is safe and habitation worthy.

The process of change is in the building itself, and the contextual setting. The changes in the building shell are real happenings in time, though mostly ignored, being too close for perception. The changes in its contextual setting are of subjective perception, and so seem to be unreal. Both of these become affective when economic value or its functionality, is degraded.

Natural changes occur in buildings irrespective of the intensity of use. Such changes occur in buildings that are over-used, mis-used, under-used or not at all-used. Some conditions like over-usage may hasten the pace of change. Natural changes cannot be terminated, but perhaps can be slowed or restricted spatially.

Man-made changes mainly relate to the nature of use. Over-usage reflects the intensity of use, which must be provisioned for in the system. Mis-usage results due to the abuse of the building system. It relates to the social set-up within which the building exists, functional inadequacies and ambiguities about the form. Under-usage and non-use of a building are circumstantial factors, and in that sense the changes may be more for natural reasons then man-made causes. Man-made changes are involuntary as well as malicious.

Redeveloped Dock buildings

Redeveloped Dock buildings

Buildings during their life change, occasionally and continually. These changes are intentional actions as well as inadvertent changes. The later type of change occurs on their own (as the inevitable process of ageing), in spite of all the remedial measures, and also due to the side effects of the intentional changes.

Old neglected building, Princess Street Manchester

Old neglected building, Princess Street Manchester

Intentional changes in buildings are due to maintenance, repairs, alterations, additions, extensions, preservation, reformation, conservation, downsizing and demolitions. Some of these changes occur several times in the life of a building. Some changes are made at regular intervals as a precautionary measure, because their needs are probable. Other changes are made very rarely, only when there are compelling reasons.

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OPENINGS and FINISHES

Post 220  – by Gautam Shah

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Openings like Doors, Windows, Gates and Gaps have several architectural components: 1 Surrounding areas of the openings, 2 Structurals of the openings, such as lintels and surrounds, 3 Frames of the openings, and 4 Surface of the opening including shutters such as panels and glazing.

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Surrounding areas of openings have ancillary architectural elements to diffuse or highlight the opening in the wall. The nominal elements like the walls, columns, pilasters, cornices, arches, or abutment, are modelled to envelope the opening. The modelling also creates a consistent style for openings of various types, sizes and depths (setting in the wall thickness). Treatment of surrounds is used to link and coordinate other openings into a façade composition.

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Surrounding areas of the openings are used to scale and enhance the presence of the opening in the wall. Opening specific surround treatments are done with better materials, well executed for exploration of the style.

Palazzo_Te_-_Veduta_del_giardino_interno

Larger architectonic elements as stand alone or repeating units create interest of their own. Walls, forming very large surface area, however, are treated with Textures, Colours, and Patterns. Other surface treatments include: materials with various levels of translucency, make-believe or pseudo finishes, glowing or illuminated finishes, compositions of light and shades, vivid or changeable presentations.

Palazzo_medici_riccardi,_finestra_inginocchiata

Textural treatments: Such surface finishes include uniform textures, patterns of masonry and structural joints, and definitive projected cornices, bands or grooves. The textures are used to enhance the surface qualities of the materials. The textural patterns are also oriented to follow or go counter to the nature of the openings. One of the most important considerations for texture creation is the nature of illumination in terms of the solar orientation, angle of incidence over the face, and the common view position. The density of the textures is an important tool for creating the contrasts. The portion in shadows show off as darkened colour, and this aspect was used for differentiating select portions of the surface. Textures were created over masonry surfaces by micro chasing or engraving such as vermiculation, polishing, grinding or finishing to various grades of fineness (e.g. glossy to matt). Textural treatments were also created by cladding thin slabs of marbles, granite, slates, bricks, ceramics, glass, etc. and highlighting the joints by different pointing methods (joints formation). Masonry and plastered surfaces were rusticated.

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White_Palace_of_the_Potala

Colour treatments: Colour treatments were of two types: Materials with their original colours were used, or new colours were applied through different rendering methods. Materials for their unique colour tones such as wood, marbles, masonry or building stones, terracotta, bricks, ceramics and glass were selectively used. Colours of rare materials such as gold, silver, marble, granite, precious stones, exotic timbers, sea shells, etc., were inlayed for their sparing use. For applied colours many different bases -substrates and application techniques were employed. Stucco and Fresco over masonry surfaces, staining and dyeing of wood surfaces, enamelling and baking over glass surfaces, and dyeing, embroidery and other embellishments of draperies and furnishing fabrics; were the commonly used methods. Masonry colour palate consisted of oxide minerals, as these were sun-fast. Calcimine and Distemper colouring has been the major painting system for masonry and plastered surfaces since medieval period. China has a tradition of painting door lords or guardians over the shutters. Oil panting became more common from 1700’s, whereas polymer paints (plastic, vinyl, latex) became popular after 1950’s.

Compañía_de_Jesus_Décembre_2007_-_Vue_de_Face

 

Patterns: Masonry surfaces are the chief areas for surface treatments relating to the opening systems. The patterns emerged through the use of materials of constructions, or are rendered. Romans used the masonry joints’ patterns such as opus incertum, opus recticulatum, opus testaceum, and opus maxitum, and manipulated them around the square and arched openings. The stone surfaces were finished as polished or textured with irregular grooves intended to resemble worm tracks. Vermiculation is one form of surface rustication, which creates a decorative contrast between similar surfaces. The rusticated plaster or stone work is ordinarily confined to the lowest story of a building, and the finely dressed ashlar or plane plasters are applied in the upper sections. Vermiculated rustics are found in several areas of the Louvre, Paris. Patterns were also created by arranging or inlaying the assorted or variegated marbles, such as in the façade of the church of the Certosa di Pavia (1491) or as in most of the Venetian architecture. The style of pattern and colour coordination became common in the architecture of northern Italy.

Hamburg,_Speicherstadt,_Parkhaus_Speicherstadt_--_2016_--_3001

 

‘The favourite building material of northern Italy was brick with terracotta trim and decoration, a combination by means of which a pattern of light and dark was created over the entire building. On occasions when stone was used, as at the Palazzo Bevilacqua in Bologna (1479–84), the blocks were cut with facets forming a diamond pattern on the façade. This was actually a decorative treatment of rustication. Even the Classical orders were affected by this decorative approach. Classical pilasters often had panels of candelabra and arabesque decoration in delicate relief on the surfaces of their shafts; the lower third of a column was frequently carved with relief sculpture.’

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Structurals of the openings

These are lintels, door-heads and surrounds, cornices, pediments, etc. These are made with better-tougher material when a critical structural role to play. The material selection, in such cases differs from other architectural elements and contrasts in terms of colour, grain orientation and texture. Palladio replaced such carved elements of stone with baked terracotta pieces, but coloured them to look like stone entities. In later periods buildings had plastered or stucco finished, that were cheaper and easier to form then in stone. The coating finishes equalized the expression of diverse elements of the opening system.

Persepolis1

In Central Asia, such features are highlighted with use of ceramic mosaics. The surface finishes are used, both to equalize or differentiate the elements of the openings. The colour and pattern, both created the surface differences, but without a strong dimensional depth.

Jame'h_Mosque,_(Friday_Mosque)_Portal,_Yazd,_Iran_(14473889644)

Symbolic association with certain colour schemes is used to associate such buildings to specific religion, tribes, clans, trades and functional uses.

Frames of the Openings

Surrounds and frames were the same in pivot-based openings. This began to change with hinged shutters, requiring a fixing frame. The frame in revival period became more elaborate, and had greater depth to cover the entire gap-side of the opening. In many such cases the frame and side panelling (over the face of the depth) became indistinguishable. The frames for hinge fixing were mainly of wood, and retained the identity of wood. The frames of heavy section but of low quality woods were masked by wood panels or veneers.

Sugamo Shinkin Bank Tokyo

Frames were left as of natural wood or blackened (not painted) for contrast and to enhance their slenderness against the bronze or glass. It was in post Renaissance periods the openings’ frames were brilliantly coloured to contrast against the brick, stone masonry or plastered and stucco covered exterior wall surfaces. Staining remained the chief method of colour toning the wood.

House Old Wooden Window Wood Indoor China

The entrance doors however, were made of some of the best and exotic varieties of timbers, polished and stained to show off their colour and grains. The Colonial period in USA and revival periods in Europe saw the emergence of all white doors and windows. Black or darker frames enhanced the sub divisions of the opening, but white paint dissolved their presence.

Double-hung sash windows were mostly painted white, and had clear glass showing the curtains of the interiors. The later effect was used as the glass of larger sizes and better clarity became available.

First_gateway_to_Ranthambore_Fort

Finishes Over the Surface of the Openings

An opening’s surface is characterized by several features such as the extensive face of the shutter, the presence of the framing elements and dominance hardware and other adornments.

The shutter and frame are either contrasted or matched. Contrasts occurred because the functions of the frame and shutter (panels) were different. For very large shutters, wood panelling required many joints and so bronze was the preferred material. For windows, glass was the most perceptive surface. Bronze panels had patina as the finish whereas glass panes had a grayish tone of iridescence and transparency. Both the materials are very distinctive, but difficult to contrast or equalize in colour or texture.

White Sash windows

During daytime the glazed face invariably has a greyish tone, often reflecting the surroundings and the sky, which contrasts with most other materials except the metals like steel, chrome, bronze with patina, silver or tin. Pot glass had coloured presence but effective when back lit very brilliantly after sunset, but such illumination was not available in that age. From an interior side the stained glass filled the interior so profusely that it required sobering through use of grisaille painting technique over the glass or use of a non stained cristallo glass.

In stained glass treatment the need to stretch the story board across many sections of the window was so strong that all framing and dividing members like muntins and cams were made slender at least on the face side, and additionally dissolved by colouring them with the same tone as the outlines in the picture.

Museu de Arte Contemporáneo de Castilla y León, Spain

Fort and other large doors were without glazing, and for the wood or metal no weather resistant oil paint system was available till later part of 1700’s. Wood shutters were left in natural state, though often had inserts or sub-members of exotic timbers, or were adorned with metal hardware, decorations, medallions, sheathing and inlay of precious metals. In windows polished brass muntins were brighter, stronger and could be leaner in size.

Doors with cast and embossed insert panels made of bronze, copper, brass, and wrought steel were embellished with gold, copper or silver on entire face or over local details. For these purpose metal working techniques, like: carving, embossing, chasing, repousse, matting, etching, damascening, niello, ajoure, inlaying, overlaying, gilding, etc. were used.

Ghiberti -Gates of Paradise Florence

Ghiberti -Gates of Paradise Florence

The craft of bronze casting was a thriving industry from 12th C. Lorenzo Ghiberti’s Gates of Paradise -Porta del Paradiso (1425), Baptistery of the Florence cathedral, is the high point of this craft in Florence. It lasted through the Renaissance and Baroque era. The bronze doors consisted of 28 panels illustrating New Testament scenes of the life of Christ. Bronze doors inlaid with niello work were earlier produced mainly in Byzantine area (during 11th and 12th C.), began to be produced everywhere in Europe.

In England in the 17th century the door panels were raised with ‘bolection’ or projecting mouldings, sometimes richly carved. In the 18th C. the mouldings on the stiles and rails were carved with the egg and tongue ornaments. Doors were also made of wood veneers and wood inlay.

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MODULATED MEASURE SYSTEM

Post 219 – by Gautam Shah

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Synthétiseur_E-mu_(musée_de_la_musique,_Paris)_(16991810569)

Raw materials or Finished product‘s are transient terms for goods. A finished product is a raw material for some other process. Raw materials procured in a linear, square, volumetric, weight or liquid measures, get processed into a different ‘measure’ entity.

For products transiting from one measure phase to another, a persistent dimensioning system is very advantageous. Consistency of dimensions allows use of standard tools, equipments, plants and technologies. The dimensional consistency, if properly recognized and supported, can rationalize the conversion processes, storage, handling, and waste management.

For example metal ore is mined in volumetric measure, transported by its weight measure, bought for its yield rate value, refined into ingots for weight measures, rolled into metal sections to be used for their strength aspect.

Allegheny_Ludlum_steel_furnaceIn the Post Industrial Revolution period, trade and industry all over the world recognized the need for a Universal Dimensioning Discipline. At that time better coordination was also required for conversion and transmission from old measurement systems to the new SI system of measurements (Le Système International d’Unités). First worldwide understanding emerged in the adoption of SI as the Universal Measure System.

ISO System

ISO MODULAR PREFERENCES

The SI also recognized that, measures as above, are either too large or small for nominal use. Such a widely spaced (1000 factored) measurement system was not amenable to unit formation for processes like planning, design, production, transportation, fabrication or execution, etc. ISO (International Standards Organization) as a result devised a practical modular system of dimensions known as ISO Modular Preferences. Most National Standards (including Indian Standards) are recommending and enforcing the same for various products and processes.

Container_stack_on_Edith_Maersk_(7098374635)

The ISO Modular Preferences help in both, dividing a whole into logical parts and combining parts into a rational whole. It also accommodates traditional modular systems, such as foot-Inch and earlier versions of the metric systems. Typically, the Foot (12″), the most popular measure of FPS has been accommodated (but not the 1/4 or 1/5 part of the Meter such as 20 or 25 cm or 200 or 250 mm). This was done for wider acceptance and to achieve a gradual changeover.

ISO preferences

First Preference is favoured by the building materials’ industry. Plywoods and other wood products are available in modules of 300 such as 600, 900, 1200, 1800, 2400 etc. Large buildings are designed with 300 as the modular measure. But, for smaller spaces such as Bedrooms, toilets, second preference of 100 is used as a module.

Second Preference is considered to be the most appropriate one for Building components and Planning. Glazed Tiles are available in multiples of 100 mm, with sizes like 100 x 200, 200 x 200, 200 x 300 etc., and also in sizes such as 150 x 150, 150 x 200 etc. as a carry over from the old system. Fabrics have widths of 600, 900, 1000, 1200, 1800 etc. When we order Windows or Doors the width x height are measured in 100 mm increments.

Third and Fourth Preferences are more preferred for objects smaller then 300 sizes. These preferences are not to be used for basic object sizes of more than 300, unless there are strong economic or functional reasons for doing differently.

Raw material to product and wastage management through dimensioning discipline

Raw material to product and wastage management through dimensioning discipline

IMPLICATIONS OF THE MODULAR COORDINATION OF DIMENSIONS

There are many products where smaller modulation or variations are desirable such as Garments and Shoes. ISO Modular Preferences, do not consider the variations in naturally available materials. Furniture, fittings and fixtures designed with ergonomic profile or serving anthropometric, inconsistencies have no specific accommodation in this system.

ISO is a modular system to form a grid or matrix for macro planning and in that sense takes a superior position. Components and parts are expected to fit in the system. As a result, work-sizes of components and assemblies should be determined by taking account of space for joint and allowance for tolerances.

body sizes

Garment Sizes

The ISO modular system is based on SI system (a derivative of the metric system) which originally was rational and contrived, and continues to be so. This type of Modular Coordination of Dimensions, is unnatural and does not exactly relate to human body. Its implications to our senses are extremely limited. It creates an ‘order that lacks beauty’. The system does not harmonize the variable tolerances’ requirements, and differences in fitments sizes.

size_chart_childrens

Ergonomic- Anthropometric variations cannot be part of ISO modular system

ISO Modular system has very simple and predictable progression-digression, unlike many mathematical orders and systems like Corbusier’s Modulor system.

ISO Modular Preferences, as a universally agreed system of preferred measures, disciplines design, procurement, production, conveyance, handling, storage, distribution, usage, wastage and reuse or recycling of materials. The system has provided a level ground to compare standards of various countries, and evolve world standards (ISO) for various products, services and work or operational procedures. It has made the writing of specification lucid and logical. It simplifies taxation procedures, costing, estimating, and valuation. It also rationalizes deployment of human and energy resources. It has made quality control procedures very objective.

Universal parts

Universal parts

At any cross section of time, there are many creative people, who feel stifled by such an Abstract Dimension Modulating System. But one must also concede that by its universal acceptance (through ISO), a logical dimensioning tool has been made available to a vast majority of people. The Dimensioning Tool defies all localized traditions, cultural variations, anthropometric distinctions, racial biases and geographical peculiarities. The system is unaffected by time or space.

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ADHESIVES

Post 218 ⇒   by Gautam Shah 

ADHESIVES

Historical perspective

An adhesive is a substance that as an intervening agent binds two similar or dissimilar surfaces (or objects) together and resists their separation. The term adhesive is used for substances such as the glue, gum, cement, mucilage, mastic compound, sealant or caulking compound.

Plant exudate Gum

Plant exudate Gum

Surfaces stick or remain together when forces that cause attraction are operative. A force of attraction is any type of force that causes objects to come together even if those objects are not close to each other or not touching each other. Gravity is one such force. The electrostatic force cause attraction due to differential electrical charge. The magnetic force affects objects that have magnetic properties.

Using Natural Starch

Using Natural Starch

Adhesive substances are many types. It is a solid that is dissolved by heat or solvent, a natural liquid that remains wet, a substance that in the presence of a reactant shows binding capacity, and a material that forms a longer chain (polymerization) over age or with chemical action.

Adhesives are joining substances, and offer unique advantages. The use of adhesives offers superior binding or joining in many situations. Its advantages are evaluated against other joining systems such as seaming, stitching, tying, knotting welding, forging, soldering, fusion joining, mechanical fastening, etc.

The adhesive like substances are valued, for non-invasive joining (without drilling, melting), ability to join similar and non similar materials, capacity to distribute stress across the joint surface, often without damaging the visual aspects of the objects, in some cases for demountable joining, functionality over wide range of temperature and other environmental conditions and facility to work without heavy duty equipments or energy use.

Adhesive are disadvantageous, in varied stress conditions due to environmental as well as structural loading conditions, require a large surface for adequate bonding and do not allow assurance inspection of joint integrity.

Gold Foil fixing with adhesives

Gold Foil fixing with adhesives

Earliest adhesives were plant exudates like gums and resins, and of animal origin like hide gums. The adhesives were perhaps used for joining, dissimilar materials for tools making, broken ceramics, and for waterproofing boats and canoes. Many of the primitive applications of binding materials were similar to use of painting or surface coatings materials.

Bitumen

Bitumen

Adhesive materials like, gums, glues, starches, egg whites, casein and other proteins, have been used in art work painting to fix various types of colourants. The Egyptians have extensively used animal-glues in tombs, furniture, ivory and papyrus items. Many societies worlds over have used adhesive materials to fix decorations on adornments, ornaments, etc. In Europe during the middle ages, egg whites were used to decorate parchments with gold leaves. Adhesives made of starch were used by Egyptians dating back 3,300 years, for bonding non-woven fabrics from fibres of reed plant -papyrus, and as a sizing material.

Roman concrete Vault of Pozzolana cement

Roman concrete Vault of Pozzolana cement

Limes and natural cementing materials like Pozzolana (volcanic ash), calcium carbonate and sulphates, were used in masonry work. Bitumen, tar pitches, and beeswax were used as caulk or sealants and also as adhesive for fixing statues and other repair work.

Cement masonry

Cement masonry

Wooden objects were bonded with glues from fish, horn and cheese. Hide glue was extensively produced in Holland and Fish glue was produced by the British, in 1750s.

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WOOD RESOURCES

Post 217 – by Gautam Shah 

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Wood’s appearance, warmth to touch, its ability to be worked with simple inexpensive tools, wide range of tonal hues, grain patterns and textures make it, the most versatile craft material. The only drawback for using wood, is the effect of moisture on its structural properties and its susceptibility to decay. No two pieces of timber are similar, the great variations in structural properties, colour, texture etc., make it suitable for different uses. These wide variations in a quality put the timber to a disadvantage in comparison to many naturally available materials.

Wood products

Wood products

Wood products

Wood products

Trees can be basically classified into two groups – exogenous trees (exogens) and endogenous trees (endogens).

  • Trees may be broadly grouped into exogenous and endogenous trees according to the way in which their stem diameter increases.
  • Endogenous: are trees with inward growth, and have longitudinal fibres such as canes, bamboo, palms etc. Typically it is not possible to see any growth rings in this set of trees.
  • Exogenous: are trees with outward growth (such as additions of annual-seasonal rings), like Conifers (narrow leaves) (pine, fir), Deciduous trees (broad leaves) (teak, rose). These are used as engineering timbers.
Exogenous conifer

Exogenous conifer

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Endogenous plant Bamboo

Endogenous plant Bamboo

Exogenous plants as the name suggests grow outward. The stems are formed by successive additional layer on outside. Timber is essentially derived by the new mass formed in the cambium between the wood and the bark every year. Trees of cold climates and substantial numbers trees of warmer climates are exogenous. Rings in the trunk or branch section, and pith with medullary rays extending outwards to the bark are two distinguishing features of exogenous trees. Exogens yield timber for furniture and construction. Exogenous trees are subdivided into two main classes: broad-leaved trees and needle-leaved trees, or conifers. Broad-leaved Woods generally contain no resins, and the density or weight is greater. They are usually hard, and due to their irregular structure, net yield is lower.

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The other botanical group of endogenous trees or endogens or grow inward from a hard exterior shell or, more commonly, end-wise by the acquisition of a new joint. Endogenous trees grow by forming new fibres within the trunk interspersed with the old fibres. Old endogenous stems have older and harder wood near the surface, whereas younger and softer centre. Timber from these trees has very limited engineering applications. Examples of endogenous trees are Palms, bamboos, canes, etc. These are not broadly useful for furniture or construction work, yet have their specific advantages and uses.

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Commercial timbers of exogenous trees are classified as softwoods and hardwoods, though a very misleading nomenclature. Softwoods are timbers obtained from conifers, growing above certain altitude, and are supposed to be soft and lighter in colour. Hardwoods, are timbers that originate from the mainland and tropical areas are supposed to be hard and darker in colour. Many softwoods, though, are much harder and often of darker in shades than some of the hardwoods. Inversely many hardwoods are fairly soft and lighter in colour than some of the softwoods. Botanical names and commercial names of trees or timbers do not provide a true picture. There are multiple botanical names for the same specie adding to the confusion. Same timber is likely to be differently known commercially in various parts of the world.

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Thanjavur Palace India

Timber is a very precious commodity. It takes decades to grow a commercially viable timber tree. Deforestation has become a prime issue from ecological points of view. Several countries have banned or severely curtailed and controlled the export of timber. Similarly many countries have banned import of timber to limit deforestation world wide. Many governments and local authorities discourage timber structures and other uses of timber. Government of India has enforced conditions, so that usage of timber as doors and windows and other structural purposes are nearly banned, in government schemes. Similar conditions are likely to be followed by state governments also. So over the years use of timber is likely to be severely curtailed not only due to legislation but also its difficult availability and consequent upward pricing.

Wood products

Wood Composite products

Timber grown in planned plantations is of consistent variety due to standard or a singular source of seedling or genetic derivation and grown in very controlled conditions. These results in trees with identical grain, colour and texture, belying the natural variations associated with woods.

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Wood replacement products are of broadly two types. Wood-based composites such as plywood, block boards, chip and particle boards are likely to remain available, but only for a while. The availability of such products is also going to taper off in future. Wood ‘look-a-like’, make-believe, or pseudo wood products made of polymeric composites, painted, printed or layered materials are in the market.

Unlike a metal or plastic, wood is inherently a replenish-able resource, provided production and use are controlled and matched.

 

 

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