CLAY MATERIALS for SURFACE FINISHES and PRODUCTS MAKING > Part -I

Post 706 -by Gautam Shah

Part -II will deal with ADDITIVES for CLAYS

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Surface finishes and Products composed with CLAY as the prime raw material have been used, for every conceivable purpose and in all parts of the world. Clay is preferred for : Abundant supply, cheapness, universal availability, insulation qualities, ecological value and simplicity of application. Clay finishes and products have some drawbacks like: shrinkage on drying, i.e., cracking, poor weathering qualities, lack of homogeneity in dry state, high water permeability -hygroscopic, poor bonding to a substrate peel-off, vulnerability to white ants and insects.

Kaolin

The quality of the clay-based surface finishes and products depend on:

  1. Quality of soil
  2. Fillers
  3. Additives
  4. Manufacturing processes

OxfordClay_Weymouth

Quality of Soil

Soil is a product, formed mainly from the decomposition of a rock and ashes of lava origin. The decomposed product may remain at its place of origin or get transported to other places by natural forces like water, wind etc. The product, which remains at the place of origin the Residual clays, are comparatively pure, but have less uniform particle size distribution. Materials that after being transported get deposited somewhere else are the Sedimentary or secondary clays. These are generally contaminated by other materials and have smaller but uniform particle size distribution.

Red Iron rich Earth

Principal constituents of clays are Alumina and Silica. Alumina provides the plasticity, and Silica, if free, reduces the shrinkage and warping. Composite silica, though increases the warping on baking. Other elements of clays are Calcium, Magnesium, Iron, Manganese, Potassium and Sodium. Various compositions of these elements and their crystalline structure affect the quality, colour and texture of the soil. Kaolin is the chief constituent of clays used for Ceramics production.

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Clays used for products making and surface finishing, are either Top-organic soils or Virgin-non organic soils.

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Top-organic soils have substantial amounts of organic matters from the decomposition of vegetation and human, and animals excrete. The presence of organic matters makes a soil light in weight and dark in colour. Organic soils usually show high workability and low shrinkage characteristics. When organic soils are found below an existing layer and are old, contain gallic acid and tannin in small proportions but sufficient to act as fungicide and mild insecticide.

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Virgin or non organic soils have negligible amounts of organic matters, and so reflect the basic characteristic of the predominant constituent element, i.e., lime, silica, or alumina. Non-organic soils, however, do take-on the personality of the other minor minerals present in it. Iron oxide as ferric and ferrous is the most important colourant. Other important colourants are quartz, kaolin, mica etc. Soils show a wide range of colours from off-white to yellow, light brown and chocolate to reddish tones. Non-organic soils unless constituted by colloidal particles show very little plasticity. Some mineral constituents of such soils are reactive to water resulting in swelling and leaching.

640px-Soil_material_containing_Sand,_silt,_clay

Residual or sedimentary materials available at the top of the surface, or below a certain depth, can be classified as: Clays, Sands, Silt, Shale, Colloids, Hard pan, Hoggin, Loam, Peat-Muc, Humus.

Estructura-suelo

Clays are fine albuminous products formed by decomposition of igneous rocks (lava activity). Clays are tenacious and plastic when wet. Clays are highly cohesive, have high capillaries and no internal friction. Clays are smooth to touch, sticky and plastic. Clays can also be classified according to their plasticity, or silt content. Hard clays or stiff clays have low sand content, and are difficult to excavate. Fine clays have medium sand content, and can be excavated with slight effort. Soft clays have coarse texture and are easy to excavate. Pure clays are mostly useless because of the high plasticity and excessive shrinkage on drying. Plastic clays are called fat clays, and less plastic clays and are also called lean clays.

Ball ClaysClays are black, white, red, brown and yellow in colour. China Clay is a residual material, contaminated with silica, mica, feldspar and decomposed feldspar. Ball clay is a sedimentary material of fine grain size and some organic contents. It is finer than china clay. Fire clays are formed from feldspar as residual and sedimentary deposit. Brick clays are high in iron content, and impurities of calcium compounds and organic matter.

Sands

Sands are of small granular particles, usually of stones. Sands are gritty to touch, with little cohesion. It has high internal friction and very little capillarity. Silts are soils that are somewhere between a clay and sand. Silts are slightly gritty to touch and are darker in colour than clays. Colloids are gluey matter found with clays but of ultra fine particles. The colloids absorb moisture and remain suspended, rather than settle down in water. Shale is a compressed and laminated clay with or without organic matter. Shale is plastic when wet but disintegrates when dry.

Volcanic ash deposition

Hard pan is a very dense accumulated mass of soil, consisting of clay, sand, gravel, etc. held together in a rock like but layered formation. Hard pan does not soften when wetting. Hoggin is a natural deposit of a mixture of clay with small stones, grit and sand. Loam is a soft mixed deposit of silty clay and sand in different proportions. Peat-muc and Humus, have fibrous or spongy organic matters formed by the decay of plants. These deposits are black or dark brown in colour, varying compressible in presence-absence of water and so unsuitable for heavy loads. The decomposition of organic material is more advanced in muc than in peat.

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RYUKYUAN LACQUERWARE

Post 704  –by Gautam Shah

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This article is compiled from several Internet resources and my own lecture notes on Surface Finishes.

1 Footed Tray with Figures in a Landscape and Symbols of Seven Immortals LACMA

2 Footed Tray

Ryukyuan lacquerware (Ryukyu no Shikki) is the chief craft product of the Ryukyu Islands (Okinawa Prefecture of Japan). Shikki incidentally, stands for lacquerware. Ryukyuan lacquerware represents a unique form and style distinct from the neighbouring places. These have three distinguishing features: the brilliant red colour of the background, gold patterns and use of inlay of mother of pearl. Many items and techniques of making the lacquerware of Ryukyuan, elsewhere in Japan and China are common. ‘Ryukyuan lacquers, yet, are neither purely Chinese nor purely Japanese’. The craft of making or decorating with lacquer is common in many Asian countries.

3 Red lacquer tray with gold engraving Song Dynasty

The art of Lacquerware came to Japan with Buddhism in mid 6th C from China through Korea. When Okinawa was the Ryukyu Kingdom, the lacquer items also came through trade with China during 14th and 15th C. Ryukyuan artisans over the years while exploiting, both the local and imported materials, matured the lacquerware into an ethnic craft by using Ryukyuan motifs.

21 Bowl with cover from Okinawa, 18th C Mother of Pearl Inlay work Wikipedia Image by Hiart Honolulu u_Museum_of_Art

20 Mother of Pearl

4 Lacquer case

Ryukyu, lacquerware have over the years seen several political upheavals, forcing imposition of new styles, but yet the most popular red lacquerware has survived such vagaries. During the 17th and 18th C, following the invasion of Okinawa by Satsuma the Chinese style black lacquerware production was made mandatory. It resulted in mixing up of Ryukyuan and Chinese styles lacquerware in single pieces.

5 Red Lacquer Cabinet with Butterflies

In Ryukyu, lacquerware like cups and bowls were used for offerings in religion rituals, whereas items such as necklaces and decorative utilitarian articles were offered for political gratification. The descendants of Ryukyu samurai and royalty used the lacquerware in formal places in order to forge a connection between people and the Gods. The royal Sho family of the former Ryukyu Kingdom have a set of lacquerware luncheon-basket, leg bowl and wine cups, cherished as the national cultural asset.

6 Chest with Peonies motifs LACMA

Ryukyu lacquerware, over the ages, have seen several modifications. These were, in earlier periods due to the change in patronage by the rulers and also inclusion of new patterns, materials and techniques in the repertoire. In modern times these have been mainly markets driven changes. ‘Chinkin’, the gold inlayed items had traditional vermilion and additional green lacquer. ‘Raden’ the flaked seashells inlayed articles were produced in red lacquer. In later periods Raden pieces were produced with green turban or marine snail shell over black lacquer. From 18th C other techniques were used, such as Hakue (foil lacquering) and Tsuikin (red lacquerware with raised designs). After the annexation of the Ryukyu Kingdom in 1879, Ryukyu lacquerware began to be produced by private workshops and companies.

7 Cosmetic box Kamakura period 13th C plover design in Maki-e Lacquer Tokyo National Museum

4x5 original

Hakue consists of painting a design in lacquer with a makizutsu or a kebo brush and then applying gold leaf or gold-silver powder while the lacquer is half dry. Modern method uses gold, silver, copper, brass, lead, aluminum, platinum, and pewter, as well as their alloys. The Maki-e method was initially used to decorate arms like swords, but adopted over lacquered surfaces.

8 Sutra Box Buddhist with Gold Ming Dynasty

Chinkin (Qiangjin in Chinese) technique is submerging or sinking gold as leaf or powder into carved cinnabar red-lacquered surfaces. This required very fine knife engraving work onto a polished surface. Ryukyu craft-persons preferred a variation of relief building the designs with lacquer putty, called Tsuikin, over the original Chinese method of lacquer (tsuishu) carving. Tsuikin, post 18th C is more common method. Thin sheets of Lacquer mixed with pigments are rolled out. From these various motifs are cut and applied to the craft-item. Due to its easy process, the Tsuikin is very popular process. Hananuri uses the contrast between vermilion and black lacquer. Raden uses seashell flake for inlay work. Mitsudae is a method oil painting (with lead-based pigments) motifs like flowers, birds and skies with white, pink and other bright pastel colours or coloured lacquers (iro-urushie).

10 Modern Vietnam Banana leaf motif in Gold leaf on a red background 1953

In the Heian period (794-1185), when in Japanese history Buddhism, Taoism and other Chinese influences were at their peak, sacred vessels and other articles used by temples of various faiths were of Maki-e style lacquerware. Similarly aristocrats, samurai families, merchants and artisan classes were using Maki-e style items as status symbol and proud possessions.

11 Dish (Pan)With Dragon amid Clouds LACMA

The lacquerware have evolved with many decorating techniques.

Lacquer as a raw material (resinous exudate or secretion of insects flourishing on certain trees), is not local. The material was brought to Okinawa through trade. Exclusive officers were appointed to supervise the production of lacquerware in the Ryukyu Kingdom.

12 Chest with Cartouche Figures on Donkeys in a Landscape Magnolias Plum Blossoms Peonies Birds and Butterflies LACMA

Local woods of Okinawa, such as Deigo coral tree, Sendan or bead tree, Egokoki, Gajumaru, with uniform grains are used.

13 Seal Box with Lotus scrolls & Eight buddhist symbols Red lacquerincised with Gold Qiangjin style

■ Okinawa islands are part of the northern limit of Black sea current which offers the hardest turban shells. Use of wafer-shin shell, prepared by boiling the shell in water for about a week and then pulverizing it (mijingai-nuri) is a local technique. The mix of pulverized shell and lacquer, after applications are rubbed to make a smooth surface (roiro-togidashi).

19 Korean Box, Lacquer inlaid with mother-of-pearl and tortoise shell

15 Gold Lacquer work Tray Japan 19 C

Ryukyu, lacquerware motifs include papaya, plantain, palm trees, hibiscus chrysanthemums, peonies, and other representations of islands’ coastal zone flora. Similarly local and exotic birds and animals, such as long-tailed hens, wagtails (genus Motacilla), chicken, swallows, wagtails, sparrows, mandarin ducks, peacocks and peonies, and a fictional phoenix is found here. Designs that combine and depict flowers and birds are called kachō-zu. Many non local motifs were included to serve the export markets.

Digital Capture

17 Channapatna India Lacquer coated toys

Lacquer coating is common in many parts of the world. Thin lacquer coatings or as applied in multiple layers, nominally do not crack or peel off the surface. Lacquers with additives like wax or oil as plasticizing agents can be applied on many surfaces.

16 Sake Bowls with Lacquer motifs

Shellacs finishes, were the first true clear coatings. Sankheda (Gujarat India) furniture and Chinese lacquer items are examples of shellac coatings. Shellac is a very effective coating material even in very thin viscosity, as a result its penetration and filling capacity is excellent. It is eminently recoatable so a very level and glossy surface is possible. Modern synthetic version NC (nitro-cellulose) lacquer provides a very clear and superior film compared to a shellac and maleic modified resins. Lacquers are modified with alkyds, other synthetic resins and plasticizer so as to control adhesion, softness, toughness and malleability. At fixed levels of viscosities it is possible to formulate lacquers with variable solid contents by varying the degree of molecular linkages. This property renders lacquer as the most versatile coating material for wood, metal, metal foil, leather, fabrics, fibers, plastics, stones, metals, glass, masonry, paper, ceramics, grasses (cane, bamboo), human hair and skin.

Lacquerware from across the world

Links to My other articles

446 COROMANDEL LACQUER

https://designsynopsis.wordpress.com/2019/05/01/446-coromandel-lacquer/

UNDERSTANDING LACQUERS

https://interiordesignassist.wordpress.com/2015/08/16/understanding-lacquers/

LACQUERS or NC LACQUERS

https://interiordesignassist.wordpress.com/2014/04/27/lacquers-or-nc-lacquers/

SHELLAC COATINGS and FRENCH POLISHES

https://interiordesignassist.wordpress.com/2014/04/26/shellac-coatings-and-french-polishes/

LIST of BLOGS on LACQUERS, PAINTS and THINNERS

https://interiordesignassist.wordpress.com/2015/08/17/list-of-blogs-on-lacquers-paints-and-thinners/

 

 

 

CHAIRS -1 Floor Seating

Post 699 –by Gautam Shah

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This is the FIRST of series, to form 5-6 articles on CHAIRS, (Furniture through Ages).

7 Gandhi_prayer_meeting_1946

The word Chair derives from the seat for the Bishop to read sermons. From Greek Kathedra καθέδρα (κατά-katá=down + ἕδρα-hédra=seat), to Latin Cathedra, Old French Chaiere-Chaire, Chaise to Chair, it has come to mean both, a sitting entity and a place to worship (the Cathedral). Chairs were few, and meant an office or authority (1300 C), or seat for a person presiding at meeting (1640s).

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Villages in the central mountain areas of Palestine, serving as the seat of political and military power were called Kursy. An Arabic name meaning: seat or chair. This name may have come from Kursa meaning a seat in Hebrew (based on an Aramaic word). Kursi refers to a chair, in Persian and many Indian languages. Kursi refers to the ultimate knowledge of Allah. As the word Kursi in Arabic refers also to (knowledge and scholar).

15 Bridgman_north-african-encampment

Chairs are associated for commanding positions. The presiding person must not only express formality but remain consistent, and chairs just allowed that. Formal postures, though have been gained even without the aid of any device, by sitting on raised platforms or ground. The commanding position is more due to the authority invested with a person through assignment, resources or physical power. The posture for such a sitting position essentially arrests the frivolous movements of the body. The first blocks, stools or chairs were single person facilities and stiff elements.

5 A_brahmin_priest_reading_a_Hindu_text_near_Ganges_Varanasi

13 Scheherazade and the sultan by the Iranian painter Sani ol molk (1849-1856)

Commandeering sitting postures are upright, with straight back and legs. The hands are rested in the lap or on the armrests. Seating aids have been used to rest a limb, part of a body or of the whole body. The Postures with or without a seat, backrest, and other seating aids, however, have no bearing on the climate of the place. Postures have possibly untraceable lineage, but have cultural-religious bearing. Leaders and preachers use squatting, kneeling and crossed leg positions, and so have everyone. These positions use variety of aids to enter, continue or get out of the position. The aids include, hanging ropes and chains, taller armrests, footrests, seats, armpit stands and steps.

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14 Group_of_Courtesans,_northern_India,_19th_century

The dress and the posture for seating have a curious relationship, but the dependencies are mysterious. To be on the floor to sit, one needs a loose dress, at least in the lower section of the body. The dress must be gracefully accommodated within the seat-zone. Preachers, to impress a gathering need to reinforce the spoken words with gestures. With floor seating the postural manipulation is limited. Head and hands are the chief tools for gesturing. To impress the back side (far-off) audiences gestures are enlarged, like the head is crowned with turbans, and hands covered in large sleeves.

8 The_Darbar_of_Raja_Bakhtawar_Singh_of_Alwar_(6124516683)

Sitting close to the floor as a leader or preacher implies being more in level with the audience, unless the seat is over a raised platform. Sitting at the edge of a raised platform or with some fore space, the nature sitting posture has far-reaching consequences. A person sitting on floor mats, is likely to adopt an manners that requires removing footwear before using the stage.

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12 Interior_of_a_Tailor's_Workshop_by_Quiringh_van_Brekelenkam,_Montreal

Floor-seating cultures also develop other items of furniture for access at low level, like chests over almirah. Till Britishers began to command the upper class society, dining at floor level was common. In cities like Mumbai, many houses began to have two sets of dining facilities. The floor seating, rather sanctimonious, was part of the kitchen or close to it. Guests of other communities were never served food here. The Table-chair dining was part of the drawing room and reserved for ‘special guests’.

6 Jüdische_Hochzeit_in_Marokko-1024

Floor level seating units with or without hand and back support allows some freedom for fidgeting (freedom to shift the body in micro postural adjustments). The fidgeting relates to upper section of the body. The most common ways of sitting on the floor are bending the knees inward or backward. Indian and Mughal kings’ Durbar, and in mosques the formal courts of congregation, the normal etiquette for everyone was to keep the feet tucked under the knees or thighs, and not show them up. The nobles sat on rugs, whereas Kings sat on a raised and stepped Simhasan or throne, but using the same posture.

Knees tied for Sitting posture

One can also keep legs partly folded but standing (beach sitting), with or without support for the back. Legs are stretched flat, as parallel or by crossing them over each other. The floor seats allow several other leg positions, typically South Asian or Buddhist (legs bent backward, and foot palms bent or upright), Namazi Muslim (legs bent backward but projecting on one side), Jain prayer posture left leg bent backward and right leg bent vertical upward) Cross legged with knees and back encircled by a band like a Saurashtra Gujarat, Charan story teller or Lord Ayappa of South India. Feet tucked under the knees or thighs is known as tailor style. Similarly sitting with touching two feet-palms is called Indian Cobbler work position. The Japanese formal sitting positions are seiza and kiza.

9 Srilankan_Buddhists_worshiping_at_Dhamekh_stupa_Sarnath

18 The_tribes_and_castes_of_the_Central_Provinces_of_India_(1916)_(14577156599)

Sitting is supported by buttocks, legs and feet and reinforced by spine. By remaining in un-moving position continuously and monotonously for long hoursreduces the efficiency and increases chances of making mistakes’. Sitting, for a long period in a back bent down position stretches the spine. Such postures need frequent stress relief. Many do ‘stretch their back, while being in their seat. But, if task-work platform is low, deep or non-existent, the freedom to ‘stretch the back‘ may not be used. Another stress relief can be attempted by raising the knees (in seating position) off the ground. But, in formal gatherings, for a preacher or speaker such movements convey insincerity. For floor level seats the movement to standing up and sitting down are more stressful than continuing the sitting.

17 Gajan_Spectators_-_Panchananda_Mandir_Complex_-_Narna_-_Howrah_2014-04-14_0321

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SASH WINDOWS

Post 691 –by Gautam Shah

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21 red_building_architecture_stone_exterior_old_windows_home

The word sash, derives from the French chassis, which means a frame or a window shutter that holds a glass pane. Technically sash windows refer to an opening system where the framed glazed panels are opened by sliding vertically, or horizontally, against casement windows where shutters are hinged and open sideways. Sash windows, when opened, have no shutters projecting out, so resist rains better and pose lesser fire risk. Sash windows are less susceptible to warping due to moisture, as the shutter is bounded by a frame. Sash windows open by remaining within their frames, so do not distract, as do the hanging shutters of the casement windows. The casement shutters had to be of small-width, or tended to ‘drop at the free edge’. The small shutter width required many mullions to divide the opening. The wrought-iron hinges and lead cames of the casement windows were dark and heavy, compared to the clean image of the sash windows.

1 House_close_to_Avenida_Paulista

Sash windows allow control over air ventilation, as it can be opened to a small slit to nearly 50 % of the opening. By keeping open both the top and bottom of a sash window by equal amounts (in double hung sash window), it allows warm air to leave at top and cool air to enter through the bottom. This facility of controlled ventilation saw major drive for use of Sash windows replacing the Casement windows.

9 Gulllotine Sash Window Châté_Lîzabé_f'nêt'

The earliest-known use of sash windows was in the later part of the 17th C. Sash windows with their better proportions and elegance compared to casement windows, soon became the most important visual element in buildings of the 18th and 19th C. Sash windows became so popular that people who could afford, replaced the leaded-light casement windows. Many 16th and 17th C houses have ‘replacement sash windows’. Such changes, however, were affected on the main facade only, less prominent facades and side faces continued with the original casement shutters.

3 At_Paraty,_Brazil_2017_100The window tax (during 1696 – 1861, in England) forced people to wall-up unnecessary windows to save tax, and also add fictitious windows for the sake of composing a facade. In spite of the taxation (window tax and a heavy excise duty on glass in 1746) discouragements, this was the period when windows design saw some of the most innovative changes.

Windows were initially positioned flush with the front face of the building, but great fire of London forced authorities, in 1907, to set back all windows by 4″ from the outer face of masonry. To further reduce the risk of fire, in 1774, the exposed wood box containing the cord and weight mechanism was required to be concealed in the side masonry.

15 Archiepiscopal_Palace_in_Salvador_Southwest_Elevation_Windows_2018-0192

The first sash windows of 17th C were glazed with very heavy glass requiring thick oak frames and glazing bars. However, with the availability of thinner cylinder glass from 18th C onward during Georgian period, sash windows became lighter and elegant. Production of plate glass, from 1850 onward allowed, larger panes of glass. Larger and thinner glass panes required no or fewer glazing bars. The reinforcement offered by the glazing bars was eliminated, and so horns had to be added to strengthen the junction of the meeting rail with the frame. In more expensive work, the glazing bars were made of iron or brass and painted to appear like wood.

4 St._Vincent_Hospital_(Sioux_City)_upper_windows_2

To slide open a sash shutter by sliding up or down, its weight is balanced by counterweight concealed within the window frame. The counter weight bar of lead, wrought steel or cast iron is connected to the window by a sash cord or chain running over a pulley at the top of the frame. The wheels were of wood or brass. In later versions spring balances were used. In earlier versions the weight boxes, set flush with the outer wall, seemed very heavy, but in later versions due to fire laws the weight boxes were concealed in side masonry, making the sash windows look much lighter.

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The glass used in early sash windows was not very clear, so the view through was fuzzy. The divided pane divided and framed the view into smaller bearable units. The presence of glazing bars, was a ‘relief’. As glass technology developed larger panes, free of the blur and blemishes were available requiring thinner or no mid glazing bars.

2 Archiepiscopal_Palace_in_Salvador_Southwest_Elevation_Window_2018-0191

The earliest sash windows were of natural wood colour, with brass and cast steel hones, joggles, weight covering plates etc. Curved horns, multi-arched heads, intricate mouldings, leaded lights and latticework started to appear in the sashes, which were often grouped into impressive bays and offset with ornate stone reveals. The shutter and the side box were made from different quality of wood. The sash window was a strange mix of materials and finishes. White painted sash windows provided single finish effect, very well contrasted by the brick masonry. The white colour over glazing bars also reduced their presence against the glass, making the windows look more elegant. The preference for white colour sash windows has continued till today even though materials have changed from wood to plastics, steel and aluminium.

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Before 1887 buildings tended to be painted in one colour, usually white, beige or gray. But later people began to paint their houses in lighter and brighter colours. The vibrant colours became a key identifiable feature of Victorian architecture. The latter part of the 19th C brought a new attitude toward colour, but sash windows continued to be painted in the Queen Anne style of white.

geograph-1935914-by-David-Wright

Sash windows originated as an opening system with two distinct sections: the top was of fixed glazing (divided into smaller lites) and the bottom section had a casement or sliding (vertical) sash. Some exceptional buildings had exterior-wall flushed windows with sash sliding horizontally and parking on the side wall.

Divisions in Sash

The bottom and top sashes (two are not necessarily of the same size) were divided into 3 x 2 =6, 3 x 3 =9 or 4 x 2 =8 glass panes. Each vertical rectangle reflected the proportion of the whole window. The 3 x 2 = 6 glass pane divisions have been accepted as the classical pattern for sash windows.

Boston USA Historic houses

Windows with one movable sash are called single-hung sash windows, to contrast from double-hung sash windows, where both sections open by sliding against one another. Alternatively, one shutter opens by sliding and the other opens out or inward with simplex hinges. Simplex hinges allow the shutter to get locked on one side while the other side is freed for opening for escape or easy cleaning of shutters from both sides. Typical double-hung windows of Georgian architecture feature the lower sash in front of the upper sash. The fixed sash at the top allowed it to match the curvilinear arched openings.

1 windows_old_building

Triple and quadruple hung windows are used for tall openings, common in New England churches. Among the numerous types of 18th C sash windows, the tripartite or Venetian consisted of a central sash with two side lights, one pane wide. The side lights were often fixed, with the sash cord running over their heads from the central sash into the weight boxes.

geograph-5049487-by-Philip-Halling(2)

In tropical climates, double-hung sash windows were covered from outside by fixed louvered shutters. Some double-hung windows have a full window screen that needs to be positioned suitably over the open section. Sash windows were also built to appear as casements in Gothic and Tudor Revivals. These often involved elaborate detailing with moulded mullions and even concealing the boxes for pulleys and weights.

White Sash Windows geograph-2696053-by-Stephen-Richards

The growth in use of the casement increased during the Edwardian period, and by 1910 many houses were built with timber casements, with sash windows relegated to less important elevation. By 1939, the use of sash windows was confined to neo-Georgian buildings, particularly post offices, banks, public houses and local housing estates.

geograph-2660538-by-N-Chadwick

Georgian Windows are classical double-hung sash windows. Early in the 18th C, Georgian window of 3 x 2 =6 panels per sash matured. This basic configuration ofsix panes over six panes’, remained in use even after the advent of larger panes in the 19th C. Georgian sash wood windows remained widely used form till the use of steel casement windows, as a cheaper and functionally superior option.

American_homes_and_gardens_(1911)_(17969892148)

8 Horizontal Sliding windows geograph-1620701-by-Alan-Murray-Rust

Horizontal Sliding Sash Windows have two or more sashes that overlap slightly but slides horizontally within the frame. In UK, these are sometimes called Yorkshire sash windows, presumably because of their traditional use in that area.

Box-head Sash Windows have shutters sliding vertically into the wall space above the header. Guillotine Windows have only one of the two sashes, usually the top one dropping down. The early versions of windows were without the counterweights or balancing system, and so had a tendency to come slamming down. Hanging Sashes are hung on a cord connected to counterweights.

 

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CASEMENT WINDOWS

Post 688 –by Gautam Shah

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Bay Casement Boothbay Maine Ocean Harbor Window

Casement windows were the most common house-windows, before the sash windows were devised. The shutters of casement windows are hinged on the side, and open either inward and outward. Casement windows provide a full open aperture compared to double hung or sliding windows. The casement shutters could be solid, opaque panelled or glaze panelled. Glazing panes are fixed to the shutter by beading or putty compounds.

Window Wood Rustic

Casement shutters opening inward cause obstruction if there is insufficient parking space for the opened shutter. Inward opening shutters also interfere with window treatments such as curtains, blinds, etc.

The shutters, if of small width open with a handle cum locking device, and if of large width require a crank or lever to open. A wind stay, or a friction hinge is necessary to keep the shutter open in windy conditions, and an espagnolette is used for locking. A casement window is easy to operate with its long armed handle mechanism and so ideal for difficult to reach situations, such as places above cabinets or counter tops. Casement windows open out on nominal hinges or offset hinges that open the shutter little away from the side to allow cleaning, glazing fixing and painting of the exterior face. These are critical issues for casement windows that have protection bars, or are located on upper floors.

Curtain Mountains Window Architecture Outlook

Single casement windows are used on side lites as besides a door or fixed window. Average width of wooden casement windows is 400 to 500. Larger widths up to 600 are possible with friction hinges. Very tall casement windows require patent bolts at both the top and bottom ends to shut a window or keep it open in heavy winds.

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Double casement windows are of two types: one where two shutters meet over a mid member, and the other, where the two shutters meet over each other. The later is called a French window, it opens unobstructed in the centre.

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The casement shutter could be single, opening on left or right side. Casement windows with double shutters, open on left and right sides, or in the middle like the pages of a book. Multiple casement windows have even numbers of shutters divided into sets of two each, all shutters open on one side, or symmetry is created by opening half numbers of shutters on either side.

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Casement windows typically are hinged at the sides, but if top hinged are called awning windows, and if bottom hinged are called hopper windows.

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Hopper Windows: A hopper window is a bottom hung a casement window that opens similarly to a draw bridge or a coal-pit receptor or hopper, typically opening to the outside. Hopper windows are used as cellar or subterranean opening.

Hopper Light: Hopper Ventilator: These have inward-opening shutter hinged at the bottom, usually forming the upper section of a door or window.

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Awning Window: An awning window is a casement window that is hung horizontally, hinged on top, so that it swings outward like an awning or a weather shed. Awnings are transom lites, used in upper sections of doors and windows as a ventilator.

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French Window: A French window is really a type of door with a small threshold. It is also called a French door. Two casement sashes hinged on the sides to open in the middle. The shutters nearly extend to the floor and also serve as a door to a porch, garden, verandah, gallery or terrace. It is double shuttered, and both of which for the full height of the shutters, have single or multiple panes of glass. It may have a secondary set of solid or louvered shutters opening to the interior or exterior side.

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Folding Casement: Casement windows hinged together so they may fold into a confined space, such as within the wall thickness. Small width shutters also makes it easier to close without stretching out too much. Folding casements are often auxiliary shutters, such as storm shutters or Venetian shutters on the outer face or fly-mesh shutters on the inner face.

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All types of eaves and window casement shutters, projecting out, were banned to prevent spread of fire along the wall, after the great fire in London in 1707. And these forced adoption of Sash windows (opening upward or downward).

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STONES -viability now -1

Post 687by Gautam Shah

. Part 1 of Two articles

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We today have greater capacity to search over wider terrains and also reach at sub surface locations. Exploitation of stones as collection from the surface or extraction from various depths is not a major technological problem. There are other issues that are forcing reappraisal of Stone as the viable material of construction. The issues are > economics of transportation, wastage in production, and reuse of the material as debris and production residues.

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Stones, like the clays-soils are universal materials of construction and require very simple technology. There are Three essential sources of stone: 1 Surface collected stones, 2 Extracted stones, 3 Wastes and debris stones. Use of the surface collected stones in original size-form is easiest. Such stones, however, require down sizing and form dressing, before carriage to a place of use. Extracted stones are surface protruding and subterranean mass. These are often stratified or layered. Stone extraction causes ecological devastation due to removal of the top burden, large volume of reject-mass, and wastage of local cleaning, cutting and size dressing. Wastes and debris stones are man-made endeavours. Wastes occur at points of extraction and location of constructions, whereas debris occurs due to the demolition of structures. These need sorting, cleaning and transportation.

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To make Stones viable now, Technological Developments and Materials Management are required. Stones are used for their mass, surface and structural strength. These can be exploited further by new design, joint technology, assembly methods, formation of composites, improved structural geometry and conversion to different materials (chemicals).

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1 Extend the Surface Area: Stones are valued for their surface qualities and the prime need is to increase the surface area. The extended surface reduces the mass / weight of the stones. The surface area of the stones can be enlarged by two basic methods: by Thin Sectioning and by Amalgamation of bits and pieces, which otherwise end up as a collection and production wastes. Other methods of optimizing the surfaces are to endow new sensory qualities and surface properties. Many exciting technologies are now available.

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2 Exploring structural properties: Stones have certain directional structural properties which can be exploited and reinforced. The efforts start with new ways of excavation, extraction and conversion of the material. Other common processes are selection, orientation, rational sectioning and controlled aeration-seasoning. Structural potential of stones can also be exploited by developing new areas of usage and new techniques of construction.

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3 Stone’s Combinative formations: Traditionally stone composites have had lime and cement as the matrix component. The explorations now relate to composites with new forms of filler arrangements and new types of a matrix.

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4 Designing geometrical or spatial compositions: Stones shows great promise in offering radically different materials’ combinative formations. The formations include various ways of combining or ‘synthesizing’ materials of diverse nature, such as, with metals, polymers, ceramics etc.

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Stones have naturally variegated constitution and surfaces. These, provide with inexhaustible opportunities to work to many different forms, sizes, and finishes. Though, qualitative consistency of man-made materials poses a great challenge to multifarious nature of stone materials. Stones have structural attributes, often called Engineering characteristics, which regulate their usefulness for conversion to: Building or Dimension stones, Veneered or thin slabs and for crushing. Similarly stones also exhibit very distinctive sensory properties that govern their use as a facing material in the form of building blocks, cladding and flooring slabs.

The opportunities of intervention operate on two fronts: Improvisations over existing methods and Adoption of radically different technologies.

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Part 1 of 2 articles

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WALL STRUCTURES

Post 682 –by Gautam Shah

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Wall structures have been prime structure for community purposes like, flood protection, irrigation, defense, terrain contouring and against erosion of land. These, perhaps preceded the walls erected for construction of dwellings. The builders from ancient times, were innately aware of the difference between a wall carrying side thrusts and bearing vertical loads. And accordingly the forms and techniques of constructions were different. The walls carrying side thrusts followed the natural angle of repose (the steepest angles at which a sloping surface is formed of loose material remains stable). The walls carrying vertical loads were designed with concern for lateral stability, and to a lesser extent worry about load bearing capacity.

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The idea of a column, as a ‘zero-sized’ wall, (like the Stonehenge) and of pillars (obelisks) may have come from tree trunks. Wood scaffolds were used for painting tall cave walls and ceilings. A series of props or poles, were used as piles or spikes for quicker formation of linear structures, such as in under-water constructions, floods, wet soils, or support against sand like loose soils.

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Earthen Wall structures for embankments or dams, for water flow regulation, storage, prevention of land erosion, against flooding, access-way (road) construction, for irrigation or navigation channels were constructed by combination of deposition or cutting-dressing. But the skill rested in exploiting the existing contours of the lands. Such structures were large and affected the entire community. For participation of large number of people, clear perception of the project and its benefit was necessary. It is apparent that such projects were executed during certain season. These were continuing efforts as added upon and improvised by several generations. Such lasting efforts can occur in societies that are politically and socially stable.

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Other walls were erected in the form of city-town walls to protect the community, and monumental structures related to burial facilities. These walls due to their extent gave impression of monumentality, and were gravity-stable and invincible forms against the invaders or marauders. Walls defining passageways are for land mass retention and ceremonial demarcation of walkways. Town walls and monumental walls, both were not ‘load-bearing’ structures. Both also related to access by large number of people, often in processions. The inevitable entry point was well marked in scale and position-location.

16 Passage tomb of La Hougue Bie by © Copyright Bob Embleton and licensed for reuse under this Creative Commons Licence.

Protective walls were often constructed as tall fences. These were made insurmountable by various means like an enhancement of height-width factors. Width was increased by forming a ditch on the face of the wall, and height was added by constructing the wall over a natural steep edge of terrain. City walls in some areas were constructed of tree trunks or wood lattices.

5 Pallisade like fence as a wall against calalry United States History Civil War, 1861-1865

Palisade in Celtic village Wikipedia image by Zureks

A palisade, was a defensive fence (also called a stake-wall or paling) formed around the military camps by Greeks and Romans. It is formed of wood stakes or tree trunks placed in a line. A groyne is a similar, but low height wall structure, a hydraulic entity for interrupting the free flow of water and restricts the movement of soil-sediments from coastal area.

7 Groyne at Mundesley Norfolk Wikipedia Image by MichaelMaggs

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A levee, dike, dyke, ditch, embankment, flood-bank or stop-bank, are naturally occurring long ridges or artificially constructed walls to regulate water. These are usually of stone and earth, and follow the course of a river. Levees and other structure require constant care by organized society. Some of the earliest levees were constructed by the Indus Valley Civilization (2600 BC), Egyptians to manage the floods of river Nile, in Mesopotamia and China. The word Levee or F. Lever, literally means ‘to raise’.

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The Greek geographer Pytheas noted in 325 BC, that ‘more people died in the struggle against water than in the struggle against men’.

The word Dyke (dijk) indicates, both trench and bank for water management. The word Ditch derives from dic, dick or dig, meaning to digging a trench and raise the banks with the excavated soil. Such earthworks acted as horizontal walling to deepen water channels, enhance the flow-rate and water carrying capacity. The water channel shaping by the side walling structures provided reliable lanes for waterways. These wall structures were formed to reduce the erosion by water flows, waves and winds.

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The first dikes and water control structures were built and maintained by those directly benefiting from them, mostly farmers. As the structures got more extensive and complex councils were formed from people with a common interest in the control of water levels on their land and so the first water boards began to emerge. These often controlled only a small area, a single polder or dike. Later they merged or an overall organization was formed when different water boards had conflicting interests. The original water boards differed much from each other in the organization, power, and area that they managed. The differences were often regional and were dictated by differing circumstances, whether they had to defend a sea dike against a storm surge or keep the water level in a polder within bounds. In the middle of the 20th century there were about 2,700 water control boards. After many mergers, there are currently 27 water boards left. Water boards hold separate elections, levy taxes, and function independently from other government bodies. -Flood control in the Netherlands Wikipedia

Mycenaean city walls

City walls are elaborate ‘fencing structures built from stronger materials to fortify a territory. The fort walls were symbols of power, so the scale was grandiose. These walls were planned at most select location, adding upon whatever natural defence features were available. Appropriateness of the site also rested on logistics of supply, of which food-fodder and drinking water, even during seizure condition, was very important. Forts housed a populated community and to sustain it, also included structures for defense preparedness and for offense capacity like ditches, gates, embankments, watchtowers, crenelation, etc.

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A moat is a ditch or long pit around a settlement with or without a fence or fortification. Moats were created by reforming the existing terrain features, or dug as a new one. Fortified structures, like castles were once sited over difficult terrains, where some natural features such as hills, elevated lands or rocky landscapes were available for some protection. Moats were additional defence provisions, formed at vulnerable spots. The difficult terrains, however, make it difficult to reform existing terrain, or excavate a new trench. Digging a moat was not only labourious, but the management of the excavated material equally difficult. The excavated stuff was used to back support the fort walls, or raise the level of internal grounds. Moats were formed along with construction of fort walls.

Linear Defense wall GorganWall

Some of the earliest defensive walls were linear formations and not any surrounding or enveloping forts. These were long barrier walls with open ends or terminating into hillock or large water body. These linear walls marked a territorial edge or boundary of the kingdom. Such edge walls had to be very extensive to be effective.

Sumerian King Shulgi of Ur, 2038 BC., built a wall that was 250 Kms long, between the Tigris and Euphrates rivers, to keep the invading Amorites out of Sumerian lands. Great Wall of Gorgan (restored and renovated by the Sasanian Persians in the 5th or 6th C) was 195 Kms long, and included more than thirty forts along its length. Great Wall of China was built as several small independent units, possibly first at vulnerable points, which were ultimately joined together during the Ming Era. It was as a freestanding regional scale defensive structure. Similarly the Anastasian wall (the Long Walls of Thrace) of the Byzantine Empire (469 C) located in modern Turkey was also not anchored at either end to any terminus. All such walls proved to be ineffectual as enemy army marched around the ends. The most known wall structure, Hadrian’s wall of Britain was built by Roman Emperor Hadrian (122 AD) to prevent frequent incursions.

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