WHAT DO WE DO WITH MATERIALS

Post 624 –by Gautam Shah

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We use objects for their many different qualities. Some are used for their structural properties, while others are useful due to their surface qualities. We try to find an object with the best combination of such attributes. Where such a combination is not easily or immediately available, we primarily try to change the object appropriately and secondarily we try to combine materials and create geometric compositions.

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Aerogel, extremely low density, low thermal conductive material. It is solid and feels like hard styrofoam to touch > Wikipedia image by Image policy

There are Four categories of essential qualities sought in objects for various purposes:

● Engineering Attributes:

Chemical -composition, phase, resistance, structure.

Physical -thermal, electrical, magnetic, gravity-metric, optical, acoustics.

Mechanical -stress/strength, form-ability, rigidity, toughness, durability.

Dimensional Features

Shape -camber, lay/orientation, out of flat, roughness, waviness.

Size -scale, proportion, orientation, nature of perception.

Surface Properties:

Colour -hue, tone, illumination, refractivity, reflectivity, opacity, transparency, fluorescence.

Texture -level and direction of illumination, perceptive organ, nature of contact, scale.

Pattern -random, rational, orientation of cut, original, altered.

Other Considerations:

Availability -local, seasonal, quality, quantity.

Costs  -access, procuring, conversion.

Conveyance  -distance, time, weight, volume.

Handling -safety, storage, containment

Manufacturing -conversion, processing

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Spider silk Cape from Madagascar golden Orb spider silk > Wikipedia image by Cmglee

For a material to be purposeful two broad considerations are required.

  1.          What one does to a material?
  2.         How the material responds?
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Moulding the earth > Flickr image by Julien Harneis

WHAT ONE DOES TO A MATERIAL ?

We seek an object with a perfect combination of many different qualities. Our quest is however further complicated when we require materials in very large quantities, and of equalized quality. We need materials locally, and often immediately.

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Laterite quarrying for stones at Angadipuram, India > Wikipedia image by Werner Schellmann

HOW THE MATERIAL RESPONDS ?

The material’s response is evident on three counts:

● Other Materials,

● Environment

● User.

● Other Materials: A material responds to other materials within its field. The reaction occurs both, in the presence or absence, of the environment and the user.

A material of a higher phase reacts more readily to a material of the lower phase -, e.g. solid to a liquid. Material with an ion charge reacts to a material with opposite ion charge. A material with lower latent energy becomes recipient.

The response of a material occurs more emphatically, through the surface, than anywhere else. Materials with their own surface systems respond in the same manner as their body would. However, applied surface systems with the same or of foreign materials show different reactions. The surface preparation, application method, and bonding techniques, all play their role in such reactions.

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Doughnut Shop achieving consistent finish > Wikipedia image by Neil T

● Environment: A material-object is affected by many features of the environment. The effects are local if directional (through specific orientation), or occur comprehensively. The constituents of the object also respond differently to specific effects of the environment. For such multilateral environmental demands, single, or mono material systems are inadequate. To serve such demands, separately as well as unitedly, multi-material-objects or composites are conceived. A surface material, covering the entity, forms its own environment for the entity. Here the situation can also be equated to material to environment response.

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Abandoned ship in the former Aral sea, Kazakhstan > Wikipedia image by Staecker

Effects of the environment substantially relate to the movement of earth-sun, and so have a time dimension. The time dimension makes such environmental effects to be temporary, permanent, recurrent, or variable. The effects of environment are structurally causative (capable of causing structural changes in a material), and also sensually attributive (capable of providing the sensorial experiences).

One perhaps cannot terminate the processes of nature, however, the effects of environment can be temporarily delayed or quickened and spatially diffused, or intensified, to programme the functioning of an object.

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Faux rustication > Flickr image by marctasman

● User: A user perceives a material-object in different terms like: Engineering attributes, Dimensional features, Surface properties and for Other considerations. A surface is the most proximate and tangible part of an object. A surface, is often the reason, why an object continues to survive in a particular setting.

surface-experience

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This was part of First chapter – Section 1 of my Notes on Surface Finishes Interior Design Notes

 

FLOORINGS

Post 586 by Gautam Shah

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Floorings, by virtue of their sheer extent are the most effective components of interior space definition. Floorings are important for visual and tactual appeal. Floorings are visually perceptible because the common sources of natural and other illuminations are from the top. Tactile appeal emerges when visual details of the floorings are not registered. And there are several circumstances when visual recognition fails to occur such as very vast extent, deficient illumination, uniformity of colour, pattern and texture, a higher floor from the eye-level and physiological deficiency of visual perception.

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Velodrome for cycling > Doubly curved flooring surface  > Wikipedia image by Nicola

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Cycle skating ramps > Wikipedia image Joshua Sherurcij at en.wikipedia

Floorings take on a very prominent role in: sparsely furnished and lightly occupied rooms, corridors and yards. Floorings are strikingly evident when observed from a higher elevation, such as upper level galleries, landings and platforms. Flooring pattern and colour become less evident on a very glossy surface. Reflections over a glossy surface of the flooring contribute to the height aspect of the space, but due to shortening of the depth aspect, add to the ambiguity. Floorings gain importance in tall spaces, rooms with invisible or non interesting ceilings (due to height, darkness and lack of captivating features), and in rooms with floors or levels rising upward (allowing larger floor area to be visible). Floorings provide some functional surfaces that are horizontal (parallel to gravity), in a straight gradient (ramps), variable gradients (roller skating), moulded to single curvature (ice skating) or double curvatures (Velodrome). Floorings in similar situations, however, could be ‘non-functional’ that is ‘decorative’. Such exceptional conditions occur in prosceniums, road verges, canal sides, faces of inclined walls or piers. Floorings are required to absorb or reflect energies like light, heat, sounds, vibrations etc.

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Pavement of Praca de Pedro IV in Lisbon > Wikipedia image by Roede

Visual floors have colour, pattern and texture through body surface, joints, inclination and stepping. Floorings that provide a pleasant and novel visual experience affects us more. Visual characteristics are used for connecting various architectural entities (buildings abutting a street or plaza), uniting diverse architectonic elements (like columns, gaps, openings), to impose a matrix of scale or discipline, (create passages, marked paths, territorial definitions). Flooring patterns are used to form segregated lots for different levels of accesses or purposes. Floorings with graphic patterns, motifs and symbols become part of road signage systems.

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Brick pavement in Piazza del Campo Siena > Wikipedia image by Zyance

Flooring is a very tactile component, unlike a wall finish or a ceiling. Tactile floors offer feeling of warmth, cold, hardness or softness. The presence or absence of texture makes for shiny or dull floors leading to safe, easier or difficult movement. Tactile flooring is used for movement of people and goods, sleeping, resting, bathing, washing, storing, food preparation, and handling and processing of materials.

Floorings are broadly classified for the degree of hardness, resiliency, resistance to scratching, staining and water or moisture absorption, capacity to conduct electrical charge, spark erosion etc.

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Stone ballast-packing against railway track > Wikipedia image by LooiNL

Simplest floorings are the natural finish over the surface of the material. These may need, levelling, dressing, wetting, curing, cementing perhaps compacting such as in clay-soil courts, sports tracks, playgrounds, cricket pitches etc. Natural Materials include, clays, soils, sands, stones, gravels, Kankar, minerals, burnt ceramics (Surkhi), Pozzolana, animal excretes and plant decompositions. Cementing compounds are water, oils, bitumen, tars, pitches, synthetic polymer binders, lime and Portland cement.

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Clay court for tennis > Wikipedia image by sk4t

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Cobble stone floor Place de la Bastille Paris > Wikipedia image by Tangopaso

Gravity laid floorings are simply laid, relying on the pull of gravity for stability. The largest and flat surface is placed touching the plane of gravity. In blocked or unitized floorings the stiffness, thickness and close fitments add to the stability. Examples of gravity laid floorings are: cobbles, brick lays, gravels, sand spreads, carpets, rugs, floor spreads, Daris, Chattais, woven mats, feet dusters, wooden boards, synthetic flooring mats, plastic and rubber tiles and rolls.

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Gravity laid carpeting in Lloyds Building > Wikipedia image by Lloyd’s of London

Cast in-situ floorings provide very extensive and a uniform surface. Cast in situ floorings are created by liquidized mass such as plasters, pastes, coatings and homogenization. The conversion processes are evaporative drying, oxidization, calcification, chemical bonding, polymerization, heat, radiation and moisture induced changes. Cast in-situ floorings are like concrete, cement cast floors (IPS), cow dung, Surkhi and lime combinations, synthetic or culture marble systems, fiber glass and other resin-fiber matrix spray-able composites, organo plastics, epoxy coats, PU coats, rubber coats, tar-bitumen roads.

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Operation theatre Flooring coating > Wikipedia image by Pfree2014

Mechanically fixed floorings are keyed to the substrate or the structure. Usually when floor finishes are incapable of staying in place due to the thin mass, lighter weight, reduced gravity (on sloped surfaces), presence of other pulling forces, small extent or spread requires some mechanical or adhesive fixing. Mechanical fastening is achieved by nut-bolt, nails, screws, rivets, cleats and seam formation. It is also done with friction, suction, surface tension, magnetic pull, electro static attraction etc. Examples of tied floors are bus and boat decks, stage wood floors, claddings, panellings, stair carpets.

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Dull and glossy floors > Pixabay image by Pashminu

Adhered floorings, at a simple level are affixed to the substrate. At complex level a layered composite system is formed by multi-layering over a substrate. Adhered finishes are superior as the entire surface is affixed, and so allows greater distribution of uprooting stresses. Pozzolana, lime, cement, are traditional binders whereas modern age adhesives are polymer and elastomeric compounds. Coatings like paints, organosols and other liquidized compounds are used. Adhered floorings can be categorized into three types: 1 Coatings create an extensive surface, 2 Films and sheets offer large tracks of surface, and 3 Blocks and units form a larger unit. The adherent besides fixing may provide padding, resiliency, insulation, electrical discharge, green or tacky bonding for easy removal. Typical adhesive bonded floorings are, Woven and non woven carpets, fabrics, mats, ceramic, mosaic metal, and synthetic tiles, metal or polymer sheets and foils, paints and coating systems.

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Spray-on composite flooring > Wikipedia image by Maurits90

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EMULSIONS

Post 577 by Gautam Shah

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Chocolate dipped ice cream on wafer cone (Flip 2019)

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

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

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

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

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

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

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

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

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Body Creams and Lotions > Wikipedia image by Gryffindor

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

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

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

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Ancient manner of Butter making in Canada > Wikipedia image

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

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

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Screen printing Binders are Acrylic emulsions > Wikipedia image

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

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Plastic Paint

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

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

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

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VINYL RESINS

Post 559 by Gautam Shah

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Vinyl is a synthetic or man-made material. In chemistry, vinyl or ethynyl is the functional group. Vinyl groups can polymerize with the aid of a radical initiator or a catalyst, forming vinyl polymers. Vinyl polymers are of many types, all made from monomers in which one or more of the hydrogen atoms of ethylene are replaced by another atom or groups of atoms. One of the hydrogen atoms is replaced to produce Polypropylene, Polystyrene and Polyvinyl chloride. Two of the hydrogen atoms are replaced to produce Poly-isobutylene (a type of rubber) and Polymethyl methacrylate. And when both carbons are substituted, it produces a complex polymer, Polytetrafluoroethylene (DuPont –Teflon).

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Vinyl LP records Wikipedia image by CFCF

Vinyl (V) as a term, coined by the German chemist Hermann Kolbe in 1851, derives from Latin word vinum = wine, because of its relationship with ethyl alcohol. Vinyl Chloride (VC) (chloroethene) CH2=CHCl is a gaseous chemical intermediate, a monomer, not a final product. It is composed of two simple building blocks: ethylene, from petroleum and chlorine a common sea water product. Due to its hazardous nature, no end products use vinyl chloride in its monomer form. In popular usage, the vinyl relates to polyvinyl chloride, basis for one of the world’s most versatile plastic material. Polyvinyl chloride is made by polymerization of the monomer vinyl chloride (chloroethene) CH2=CHCl. Polyvinyl chloride (PVC) is very stable, storable, fine-grained white powder, and not as hazardous as its monomer. Compared with other plastic materials of vinyl formulations use substantial proportion of natural resources, with low energy requirements for processing and release low quantity of emissions.

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PVC buckets Wikipedia image by Goolawfredment

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Bright multi-coloured water pots of Chennai Flickr image by McKay Savage

Vinyl polymers or Polyvinyl resins are the most common and comparatively less expensive thermoplastic. The properties vary with chemical structure, crystallinity molecular weight, additives and modifying agents. Vinyl resins are non-oxidizing, permanently flexible tough and durable. These are resistant to moisture and humidity. Vinyl resins are resistant to mild alkali, acid, alcohol, grease, oils and aliphatic hydrocarbons. Vinyl resins degrade upon prolonged exposure to heat, and UV light. The degradation products include HCl which accelerates further degradation, leading to unsaturated polymer structure that can get oxidized. This results in brittleness, loss of flexibility, discolouration. Presence of chlorine offers excellent flame retardant properties making it a choice product for electrical conduit and wiring requiring high resistance to ignition and flame spread.

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PVC Pipes New Guthrie theatre Minneapolis Wikipedia image by uberculture (Lic. cc-by-2.0) http://www.flickr.com/photos/uberculture/106597452/

Polyvinyl can be made flexible, rigid, semi-liquid, clear or colourful. PVC are of two main varieties: Rigid PVC is used in construction industry and for industrial components. Uses also include, siding, flooring, pipes, extruded sections for doors and windows and hardware. Flexible PVC is softer and pliable due to addition of plasticizes, typically like phthalates. The uses include trims, sheets, sheathing for electrical wires and cables, handrail tops, toys, water buckets, water hose pipes, vinyl music records, imitation leather (Rexine), signage, inflatable products, and rubber replacement applications. PVC resins are used for coatings for metal finishes, collapsible tube finishes, plastic (or Latex) paints, marine and food coatings mastic compounds and strippable coatings. Emulsions based on vinyl acetate are popular compared to many other latex type of paints. Vinyl acetate emulsions are odourless, dry rapidly, durable on outdoor faces and surfaces can be washed easily.

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PVC dust bin Wikipedia image by Joolz

Vinyl resins have TWO basic sets of product categories:

Polyvinyl acetate: It is a leathery colourless low temperature softening thermoplastic, with relative stability to light and oxygen. It is mainly used for water-based adhesives, binders (fabric printing) and emulsion paints.

Polyvinyl chloride: It is converted from monomer to a polymer PVC. The final product is in flakes or pellets form, which are used for product forming through solution, dispersion, injection moulding, and extrusion.

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PVC window unit Wikipedia image by Mfc3058

Other co-polymer variants include:

1. Carboxy modified Vinyl chloride and Vinyl acetate > Carboxyl modification makes it possible to formulate air drying metal coatings.

2. Epoxy modified Vinyl chloride and Vinyl acetate > Epoxy modification provides ability to cross-linked, with carboxy modified vinyl resins to achieve a thermosetting system. Such thermosetting systems have superior chemical resistance and toughness.

3. Hydroxy modified Vinyl chloride and Vinyl acetate > Hydroxy modification improves compatibility and adhesion, provides sites for cross linking.

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Wikipedia image by Asadabbas

Commercially several products of PVC are widely used.

Chlorinated polyvinyl chloride (cPVC) is a thermoplastic produced by chlorination of polyvinyl chloride (PVC) resin. Uses include hot and cold water pipes, and industrial liquid handling. cPVC is resistant to several acids, bases, salts, paraffinic hydrocarbons, halogens and alcohols, but not resistant to solvents, aromatics and some chlorinated hydrocarbons. It can carry higher temperature liquids than PVC. Due to its specific composition, dealing with cPVC requires specialized solvent cement. The cPVC capacity to bend, shape, and weld makes it suitable for many uses.

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Various thermoplastics pipes used in Ultra Pure water system Wikipedia image by Wikikart99

Various Thermoplastic Pipes used in ultra pure Water Systems polyvinylidene fluoride (PVDF), perfluoroalkoxy (PFA), ethylene chlorotrifluoroethylene (ECTFE) and polytetrafluoroethylene (PTFE)

Unplasticized polyvinyl chloride (uPVC) has strong resistance to chemical or electrochemical effects, sunlight, and chances of oxidation from water. As this is lead and plasticizer free, is used for potable water supply pipes.

(Molecular) Oriented Poly Vinyl Chloride oPVC is a comparatively a new technology material. This molecular-oriented bi-axial high performance product offers very high strength with extra impact resistance.

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CLEAR versus PIGMENTED COATINGS

Post 553  by Gautam Shah

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Paints have colourants or pigments to cover a substrate and provide new colour. Pigmented coatings constitute the largest section of coating production. Clear coatings, however, provide a see-through film on a substrate, which in additionally endow spacial surfaces, textural and other properties. Clear and pigmented coatings have been concurrently in use since prehistoric times. Both types of coatings usually have similar film forming substances, though the techniques of application and purposes these are employed are distinct. Pigmented and clear coatings, both can form the primer coat or a top coat in a multi coat system. As a primer or first coat the clear coat penetrates micro pores and seals the surface. As a top coat a clear finish endows specific surface quality such as gloss, sheen or matt finish and protection. In a multi coat system a pigmented undercoat creates a colour-equalized surface.

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Pigmented coatings, besides colourants like pigments and dyes, have many other substances that add special effects through opacity. These are metal powders and flakes, prilled materials, micro sized lints of glass and polymer fibres, glow powders for phosphorescent, luminescent or photo-luminescent effects. Pigmented coatings usually contain extenders for several purposes. Extenders are minerals of low refractive index. Pigmented coatings for rendered or textured finishes have high solid build resins, additives or false viscosity enhancers and minerals and fillers.

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Clear Coating of Shellac Wikipedia image by Simon A. Eugster

Clear coatings are translucent to transparent, which are natural properties of the resin (film forming substance) or through additives like dyes and very low refractive materials. The need for a clear coating could be functional, such as avoidance of pigment for being unnecessary, toxic, or reduce the bulk of the film and thereby better homogeneity and lesser thickness. Clear coatings offer glossy to dull types of surface textures, and provide shades like tinted, crystal clear or water white. Surface texturing like hammer-tone, wrinkling, crackled, streaking, are also achieved. Clear coatings applied to emphasize substrate colours, grains or patterns as in case of timber, leather, paper metals or fabrics. Clear coatings are applied where for any technical reason it is not advisable to colour a coating, as in case of toys, food cans, etc. Large number of clear coatings are technical applications for rust inhibition, water proofing, static resistance, etc.

Surface Dark Wooden Table Wood Timber Texture

Some of the crudest forms of applying clear coatings, are still practised, and these are surface wetting with plain water, waxes, oils or tallow surfacings, starch sizing, gum and other plant exhudents surfacing, milk, and casein coatings. These materials are hydrophilic, and many run in moist weather, collect dust and are vulnerable to fungus attack.

Painting road markings

A better alternative for creating clear coating, has been the use of distilled and modified pine tree extracts like rosin. Calcium and zinc modified rosins which are soluble in turpentine were used for cheap quality toys, country furniture and electrical wooden boards and battens. Often raw senna, umber, ochre and dyes like metanil yellow are added to these for colour toning and hide the ugly grain and defects of jungle woods. The finish has very little resistance to wear and tear and slightly softens up in moist weather.

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Pigmented coatings are used on sites, in industrial production units, by amateurs, artists, and crafts people. These coatings are applied with crude or rudimentary methods and also through high-tech facilities. Pigmented coatings contain specific minerals and other substances as pigments and extenders for rust inhibition (zinc), water resistance, electrical properties and fire resistance (such as walstonite), anti fouling agents.

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Wikipedia image by Baminnick

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Pigmented coatings are of following basic classes:

1. Architectural finishes

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  • Water-based masonry finishes
  • Other masonry finishes
  • Non masonry finishes applicable on sites

2. Industrial finishes

  • Solvent-based systems
  • Water-based systems
  • High solid coatings and powder coatings
  • Air drying systems, Low and High Temperature baking systems, Catalyst systems

Vehicle Automobile Paint Body Repair Auto Car

3. Other types of pigmented Surface Finishes and Treatments

Marine Paints

  • Marine coatings
  • Road marking systems
  • Toys’ and plastic colours
  • Leather colours
  • Body colours and make-up utilities
  • Inks

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MASONRY PAINT FINISHES

Post 547  by Gautam Shah

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Akal Takht at Golden Temple Amritsar India Wikipedia image by Author Amarpreet.singh

Architectural finishes are coatings or paints that are more often than not, applied on the site, before and after the elements have been assembled as an architectural entity. These usually dry out at ambient temperatures -air drying, i.e., are non baking types. Architectural finishes, in comparison to industrial coatings are high pigment & extender build coatings. Substrates for architectural coatings are of THREE basic categories, 1. masonry, 2. wood, wood composites and fibrous surfaces 3. metal. In few instances architectural finishes are also applied in the industrial set-up, over systems, components and parts.

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Colourful Homes at Burano Italy Venice Italy, Image attribution W. Lloyd MacKenzie via Flickr @hhtp://www.flickr.com/photos/saffron_blaze/

Masonry structures are in the form of straight or inclined walls, columns, piers, abutments, and occasionally on roads, curbs and floors. A masonry structure could be made up of unitized blocks of compacted clay, stones, cement concrete or baked clay or bricks with their patterns of joints and joining materials. Masonry surfaces may have plasters of plain or rendered faces of clay, pozzolana, lime or cement, all strongly alkaline in nature.

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Wall texture rendering Wikipedia image by Biswarup Ganguly

Masonry finishes, are of TWO basic classes: Exclusively protective coatings and Decorative finishes. Few commercial finishes provide both the qualities. Decorative finishes may be sub-classed as Interior and Exterior coatings, where the later category may offer substantial protection advantages.

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Roof coating Wikipedia image by Waller42

Masonry surfaces cover very extensive area, and so water has been the ideal vehicle for formulation and also as an application solvent material. It is abundant and cheaply available and is non toxic. Water as a vehicle, however, has no binding characteristic, and for that reason many natural and synthetic adhesive type of gums and resins are used as binders. Where such substances are not dissoluble in water, various water-based emulsions are used. Latex paints or emulsion type plastic paints form the main section of such coatings for masonry finishes. On removal or evaporation of water, the film formed maybe substantially moisture or gas impermeable, or a permeable lattice in the form or water repellent coating.

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Brighton Beach Melbourne Wikipedia image by Beau Wade

Voids over masonry surfaces are partially filled or levelled, causing a change in texture of the surface, when such coatings are loaded with pigments, extenders and fillers. In few instances this is unavoidable, but in many cases improvised `architectural’ or `rendered’ effects are intended. Fillers for such `rendered’ coatings include natural or treated mineral particles, quartz and silica sands, mica dust, glass and polymer beads, metal-dust, flakes, chips, or shavings.

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Iron Oxide wash houses Pakenham st Shaftesbury square, S Belfast Wikipedia image Jeanne boleyn

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Some of the architectural coatings are:

LIME-WASH

CEMENT PAINTS

CEMENT SURFACE FINISHES

OIL BOUND DISTEMPERS -OBD

DRY DISTEMPER or CALCIMINE

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Blue City Jodhpur, Rajasthan, India Wikipedia image by michael clarke stuff

Among the other masonry finishes, water proofing finishes constitute a major section. Such coatings are either `technical’ coats or part of multi purpose coatings. Technical coatings, impermeably seal the surface by covering all voids, pores and crevices; or cover the surface in the form of a lattice that is non wetting and so water repellent. In the former case the coatings are used where water vapour pressure is low and where a change in texture (due to filling up of voids ) is allowable, or desired. In the second case, texture properties of surfaces remain more or less intact, while the water repellence is provided by the ionic quality of the surface. Commercial water proofing coatings are based on Bitumen, epoxidized bitumen, PU coatings, silicone paints, and polymeric compounds.

Good film properties on masonry surfaces are achieved by using 100 % acrylics, or copolymers of ethylene, or acrylic esters, emulsions of vinyl copolymers. Chlorinated rubber with a suitable plasticizer, has a good alkali and atmospheric contaminant resistance. Long oil alkyd enamel with appropriate primer system work well for masonry surfaces.

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Deck Floor marking paint

FLOOR PAINTS

Floor paints are used to improve the appearance, increase abrasion resistance, reduce moisture penetration and impart spillage proof qualities. Medium oil alkyds and moisture cured polyurethane, epoxy compounds, chlorinated rubber coatings are used. Road marking and curb coatings are very similar to floor paints except that in certain cases reflective or fluorescent pigments are used. Hospitals, operation theatres, pharmaceutical and electronic assembly plants, require joint less flooring and wall-finishes for bio-pathological reasons, or for dust less environment. Such finish systems are made from of chlorinated rubber, urethane or epoxy coatings. Wood or wood composite floorings in athletic and indoor sports area require a smooth, non skidding and spillage proof coating. Such coatings consist of melamine, urethane or epoxy materials.

FLOOR PAINTS

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CEMENT SURFACE FINISHES

Post 543  by Gautam Shah

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This blog >>   was originally published 15 June 2015 at http://talking-interior-design.blogspot.in/
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Cement surface finishes occur in three different conditions:

1 Finishes generated over the cast cement products,

2 Rendered finishes of cements,

3 Cement coatings’ finishes.

The major problem with cement finishes is the consistency of colour over the surface. Other problems happen due to differences in application (casting, rendering or coating), mixing water content and quality and curing processes. The colour differences arise due to many reasons: ingredients used in cement manufacturing, particulate size and its distribution, size and colour quality, proportionate quantity of other ingredients, quality-conditioning additives and mixing procedures.

Centrifuge Cast cement concrete pods on Sea face at Mumbai, India

Cement cast products are plain or steel reinforced structures, pre cast blocks, units, etc. A cement finish of a cast product emerges due to the form-work, compaction, level of vibration (causing aeration), proportion of water and technique of casting (towards gravity, centrifugal or centripetal, short or long depth fall).

Cracks in Cement plaster due to uneven mixing of ingredients

Cement Concrete Surfaces can have finishes depending on several factors, such as:

1 Form work surface, joints and continuity, use of a release agent, absorbency of the form work surface and setting or hardening enhancer and retarders used.

2 Concrete mix proportions, ingredients’ colour, size, and texture (lighter toned aggregates and sands produce light-coloured concrete (colour of cement is variable not only from plant to plant but often batch to batch). Degree of mixing and air entrapment affect the colour. Free lime in water creates a soapy foam which also affects the colour.

3 Insufficient or uneven curing affects the hydration and eventually the colour of the concrete.

4 Inadequate vibration causes minor pockets of air bubbles, which affects the texture.

Weathered Cement Concrete at Sanskar Kendra by Le Corbusier Ahmedabad India

Rendered finishes of cement include plasters, sprays, guniting, masonry pointing, screeds and daubing. These are comparatively of thinner mass. The compaction, if any is part of the application or rendering-levelling by trowels, plasters boards, etc. For rendered finish the surface quality is fairly consistent for small-extent surfaces. For very large surfaces, such as multi-storeyed buildings, the surface differences are noticeable. These anomalies can be reduced by dividing the surface with wide intervening elements of different colour, texture, projections or depressions. Same technique is used for pointing to the masonry faces of stones or bricks. Pointing is designed to enhance the joints’ pattern, as strongly horizontal, vertical, or both. The joint is usually of a contrasting colour and of finer texture, then the main material surface. A raked joint or protruding joint looks much darker than a flushed joint or flat joint.

Masonry bricks of Cement with Fly-ash

Cement is used for creating in-situ and precast floor blocks. Use of fine sands increases the air entraining effect and reduces the work-ability. Angular or flaky sands are difficult to use in sand face plasters.

The mixed mortars are affected by the colour of the aggregates. So it is very difficult to produce a perfectly white marble mosaic tile or washed chips’ plaster unless only pure white aggregates are used. Cement and aggregate flooring such as IPS – Indian Patent Stone, Red Madras floor and Ironite (cast iron milling waste) are all affected by the colour of the constituents. coloured mortars have pigments of iron oxides (black, red and yellow). Green, blue and other colours (though not sun fast or long lasting) are achieved by use of chrome pigments.

Cement pointing over brick masonry

For vertical and ceiling surfaces ziki plaster formed with marble dust containing substantial amounts of fine mica and talc. Similarly pearl glow and a smooth surface can be achieved by including sea shell dust. Slow setting and engravable cement mortars require high workability, are achieved by addition of fully calcined gypsum or lime containing such compounds.

Cement coatings’ finishes are in the form of cement paints and high viscosity or bodied rendering formulations. Cement paints have limited life of 3-5 monsoons and re-applicability of 5-7 coatings. Cement paints are alkaline materials and applied on similar substrates, and as a result the colour range is mostly of Oxides colours. Some blues and greens of darker range are available. The chief problem is the process of adding the water, which creates flocculation and aerated mass. Next problem is application on a dried out substrates with chances of poor adhesion and difficult brushing. Rendering formulations have high viscosity, and the success usage relies more on the craft of application.

White cement + Marble chips Terrazzo

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Cement Surface Finishes have few basic problems:

fine hair cracks

honey comb voids

unbounded loose particles

foreign particles stuck on the surface

foreign particles deposited on the surface.

washable salts leached out from the surface

salts and compounds formed over the surface by the constituents of the environment

mould and fungi type bacterial growth

disengagements from the substrate -peel off.

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SURFACE FINISHING PROCESSES

Post 504  by Gautam Shah

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Surface Finishing is achieved by several processes such as:

1 Surface Levelling,

2 Surface Texturing,

3 Surface Property Modifications without resorting the first two,

4 Embellishment with other materials.

Pic from Flickr by Nic McPhee

1 Surface Levelling is done by Removal of excess material, and Deposition of new materials.

Surface levelling is achieved by removing the texture or roughness forming excess material. For these surfaces are section re-cut, ground and polished. Stone surfaces are chipped with finer chisels, or wood faces are planned to level out the surface. Stone surfaces are dressed to remove the weathered crust. Rough cut or split (sedimentary) stones are spliced into two, by a smooth saw cut. Barks of the trees are removed by axes and choppers. Timbers are split very finely to create veneers. Leather surfaces are shaved for thinning and to remove the surface hair. Leathers are split to make uppers and soles. The palm leaves are shaved to remove the stems and make them smoother for writing. Singeing or burning the surface section is used for fabrics, leather and paper. High temperature singeing removes surface fibres or hair, deoxidize impurities and in case of metal harden the surface. Synthetic or composite textiles are selectively or locally singed to fuse the fibres or filaments, and create transparency, opacity, etc. Metal surfaces are rolled over to flatten out the undulations or ‘turned’ or ground.

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Grinding and Polishing, are the two finer processes for surface-levelling of hard materials such as building stones, metals, glass, and precious and semiprecious gems, ivory, bones, leathers, timbers, pottery products, cement concrete and other cement products. Hard materials such as marble and granite, take a high gloss, whereas others like sand stones, are too coarse-grained to be polished, and can only be smoothed to a granular finish. Surface-levelling is done by sharp tools that chip away very thin section off the surface. Grinding is done by rubbing down with a graded series of coarse and fine abrasives, such as Carborundum, sandstone, emery, pumice, and whiting. Grinding wheels usually consist of particles of a synthetic abrasive, such as silicon carbide or aluminium oxide, mixed with a vitrified or resinoid bonding material. Grinding can be coarse or fine, depending on the size of the grit used in the grinding wheel. Polishing uses extremely fine abrasive substances, such as jeweller’s rouge, Tripoli, whiting, putty powder, and emery dust, to rub or burnish an extremely smooth and glossy finish on the surface of a material. Metal and glass can be ground to a mirror finish. Polishing is done by tumbling and vibratory mass-finishing media, sandblasting, pulp-stones, ball-mills etc. The polishing materials are coated on the surface of cloth, felt, or leather wheels. A special type of polishing wheel is made of soft rubber or plastics with the abrasive grains moulded into it.

Wikipedia Pic Diamond Polisher Pic by Author Andere Andre

Honing and Lapping, are used for very fine level of polishing by material removal process. Honing improves the accuracy and finish of motor car cylinder bores, hydraulic cylinders, and similar parts. There are four types of precision grinding machines: Center-type grinders, Center-less grinders, Internal grinders, and Surface or flat bench grinders.

Hubble Space Telescope Primary Mirror polishing

Other surface levelling processes include singeing, washing, bleaching, etching, and ironing. Wood surfaces on sintering create a dehydrated, old shrivelled, or shrunk surface similar to an old wood. Metal surfaces also burnt to harden the top surface and to remove oily residues, dehydrate, and descale the surface. Reverse of metal plating process removes the surface molecules to achieve matt finish.

Engraved amethyst Portrait of Roman Emperor Caracalla 212 AD

2 Surface Texturing is used to endow desired level of texture and in organized pattern format. This is done by chemical reactions with surface molecules and by mechanical means. Acid and Alkali etching are used for forming textures. Glass surfaces are etched with Hydrofluoric acid. Metals are acid etched and then neutralized with an alkali treatment. Water and solvents are used for surface making. High-speed jets of water are used to form surface patterns over partly set cement surfaces, Water used for washing out the top section of mosaic plasters to reveal the stone chips. Suctions are used to create textures in plaster surfaces. Paints are applied by roller to form granulated matt finish. Leathers, papers and plastics are hot pressed to imprint patterned textures. Recording media like CDs, DVDs have groves that store data.

Embossed leather Japan

3 Modifying or Refashioning the surface sections is done to change or equalize the surface properties of objects. Metal and glass surfaces are de-stressed by controlled radiation including heat treatment. Annealing and Hardening, are heating and cooling processes to change the molecular arrangements within the entire body, or just surface sections. In case of polymers heat treatments are used for chain linking. Textiles become de-creased or creased on pressurized with heat treatment.

crimped hair

4 Embellishment with other materials, are used in a superfluous or applique process or as an integrated process.

Applique processes are like casing, cladding, layering, or lamination, lapping, gilding and coating. Cladding is common in masonry work for a new surface, insulation, waterproofing, etc. Casing is done to metal structures for rust inhibition, static discharge, isolation and fire protection. Layering or lamination is common in composite formation through co-extrusion processes.

Metalized Film for car glass Wikipedia pic by Author (original uploader was Steevven1 at en.wikipedia)

Integrative surface processes are surface molecular deposition or surface alloying systems. Molecular deposition of metal compounds or ceramic forming (non-metal) materials achieve a very thin body deposition. Polyester metalized films offer solar radiation cut-off. Metal plating through anodic transfer also creates very thin body layering. Metal deposition over plastics, ceramics and filaments provide dual qualities. Coating systems form very vital field of material addition. Coatings are applied in a liquid phase or get converted to it, at the time of application (such as in case of powder coatings). Coating deposition is aided by electrical charge, pressure or spluttering. Many of the surface addition processes are intermediary treatments for the next lot of surface treatments. Alkaline or acidic washes or solvent wetting leaves substances that are beneficial for other subsequent applications. In medical field skins, tissues and muscles are planted to encourage fresh growth.

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METAL EMBELLISHMENTS -PAINTED ENAMELS

Post 501  by Gautam Shah

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Surface finishing or decorating with a foreign material is a very ancient technology. Metals have been embellished by several techniques. Metals have been coated by metal plating, surface alloying and deposition. Metals have been inlayed with metals, precious stones and objects.

Vairochana_Buddha,_China,_Qing_dynasty,_19th_century_AD,_jade,_gilt_bronze,_enamel,_pearls,_kingfisher_feathers_-_Royal_Ontario_Museum_-_DSC03754

These include:

Damascening a technique of encrusting gold, silver or copper wires in the finely chased surfaces of iron, steel, or bronze.

Niello is made from black metallic alloy of sulfur with silver, copper, or lead. It is filled in chased or engraved patterns over silver. The surface is heated for the niello to melt. On polishing the surface gets a dual metallic effect.

B.v.H._Niello-2

Granulation is made by soldering or fusing granulated beads of silver or gold to effect a bloom to the surface than of a beaded surface.

Filigree is made by forming a fine network of very thin wires fused selectively and than fixed on a metal surface of an object.

Ajouré is similar to filigree but the fine network is created by cutting or piercing the patterns in the metal. Raised patterns or cut out motifs are also fused onto the surface.

Luxe_&amp;_Antiquité44_bracelet_ajouré

Embellishments with Other Materials were formed using precious stones, exotic substances such as rare woods, metals, ivory, horn, beads, sea shells, jade, and amber, and niello-work, fixed into chased or performed cavities or depressions. Fixing was by wire, metal forming, heat-fusing, thread knitting and knotting.

Inlay works are of many varieties. Pre-formed cavities or depressions are filled in by many different materials such as wood, stones and metals. The fixing is with tight fitting, adhesives, or by hammering a ductile metal.

Gilding is application of metal like silver, gold, silver, palladium, aluminum, and copper alloys, in the form of very thin foils. Gilding by gold or silver foils requires as no adhesives as sufficient electrical charges attract the foil to the base, however for permanent fixing (on exterior use) some form of adhesives are used.

Overlays can be defined as metal sheathing or cladding by metal sheets that are slightly heavier than used for gilding. Overlaying is also done by applying a gold amalgam (gold+mercury) and than removing the mercury with heat.

painted enamel on copper 290x 240mm

Enamelling is a metal embellishment technique wherein a vitreous glaze is heat-fused to create a very long lasting decorative effect of brilliant colours. (Read on > Enamels).

Snuff bottle, northern India, 18th century, gold, gemstones and enamel

An Enamel is a compound of flint or sand, red lead, and soda or potash which forms a glass like material on being melted. Low temperature fusing is easier to manage, but creates a soft glass surface that is prone to cracking. Hard enamels are formed at higher temperature are better lasting, but it is a slightly difficult process.

Miniature of Marie Louise d’Orléans, future Queen of Spain by Jean Petitot le vieux (1607-1691)

Painted Enamels are like miniature oil paintings. These are made on a metal base or plate covered with a layer of an opaque enamel. The opaque or white enamel base is further embellished with ‘glass forming but with colouring materials’, rendered by fine needle painting, spraying, screen printing, spattering, scratching or block printing. Separate firing is required for each of the colours. Artists created portraits and other art subjects on very small metal plates, surpassing richness of larger canvass-based oil paintings. Painted Enamels being very small could be carried anywhere as a personal item of collection or treasure. The colours are permanent and non-yellowing or fading. The painted enamel has remained a craft and is not accepted as medium of art. The painted enamels of China are known as Canton (Guangzhou) enamels. Painted enamels are termed by the Chinese yangci (foreign porcelain).

Coloured enamel embellishments were created over arms, armour, mirrors, bowls, cups, chalices, spoons, and miniature pendants, tableware, wall and ceiling panels, signages, table clocks, and snuffboxes.

‘Mercury’, painted enamel and gilt on copper mirror back

Five main types of enamelling processes are used:

Champlevé (French= raised field) enamels are created by scratching or etching a copper surface, which are than filled-in with pulverized enamel material, fired and polished.

Cloisonné (French= partitioned) has very small partitions or cloisons formed with thin metal strips. The partitions are filled with pulverized enamel and fired.

Basse-Taille (French= low cutting) process is a kind of champlevé, but is applied to silver or gold. Here the depressions are filled with translucent enamel, which allows the substrate or patterns on it to be seen.

Plique-à-jour (French=open braids) enamelling resembles cloisonne, but here the partitions form a separable lattice. The lattice is removed after firing, giving an effect of stained glass. It is exceptionally fragile work.

Encrusted Enamel: Encrusted enamel or enamel en ronde bosse is prepared by spreading of an opaque enamel paste over slightly roughened surfaces of objects such as small figures.

Binding representing the Crucifixion of Christ, Limoges (Limosin, France) champlevé enamel on gilded copper

 

UNDERSTANDING LACQUERS

Post 498 –by Gautam Shah

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Cosmetic Box

In early 1920 Lacquers were considered industrial coatings, mainly used by White-goods and Automotive industry. Earlier to this period a Lac or Shellac coatings were wood craft finishing techniques and material. Industrial age lacquers were favoured due to their fast drying and non-yellowing properties. Clear Lacquers were increasingly replacing tin as MS sheet coating for food packing but were found suitable for aluminium sheets packing such as collapsible tubes and canisters. Lacquers were also used for the nail polishes and as hair fixing sprays. These lacquers as the name suggests were not made of natural Lac or shellac but from Nitro Cellulose. The lacquers needed thinners of various types for different application technologies and seasons.

Lacquer Paint Pic from Wikipedia by Author Victorgrigas

Oil paints based on Alkyd resins or GP Enamels need thinner of single solvent material such as Genuine turpentine, Mineral turpentine and in few instance Naphtha or superior grades of kerosene would work. These solvents singly can work for all application needs and for cleaning-washing post-painting work. With alkyd-based paints, a resin is the film-forming component. It is reduced in viscosity during the manufacturing and later during application. The requirements of solvent-s differ according to ‘length of the resin’ (which designates the proportion of oil versus other modifying-polymerizing agents, such as typically a phthalic anhydride). Short-oil length resins may require stronger solvents. A solvent that dilutes the viscosity alone may not achieve application level of viscosity. Some type carrier or diluent solvents are required which acting as a ‘carrier’ material help achieves application level (such as spraying) viscosity. The carrier solvents evaporate fast before the chain linking (and so film forming-drying) process starts at ambient temperature, raised or baking temperature or through a catalyst enabled reaction.

Wood Brushing Lacquer Pic from Wikipedia Pic by Author Mk2010

The word Lacquer has become a misnomer. A Lacquer in nominal usage means a coating system that is fast drying, tougher and non-yellowing. All lacquers, however, are not NC (nitro-cellulose) lacquers. Other Lacquer coating systems formulations are based on Acrylic resins, Amino resins, Urethane and epoxy systems. NC lacquer dries with evaporation of solvents, at ambient temperature or often in warm chambers. Other formulations require baking-stoving environments or have two-pack system (a catalyst and paint mixed just before application). A NC lacquer film can be wetted-dissolved after drying (such as Nail-polishes of pre 1965 era) by a thinner, and are called ‘non-convertible systems’ (product that does not get chemically converted into something else). But newer generation-lacquers cannot be dissolved or removed easily after drying, and are called ‘convertible systems’ (product that gets chemically converted into something different).

Box Lacquered

Lacquer Nail Polish Pic through Wikipedia -Source http://www.flickr.com/photos/zitona/4733601645/ by Author » Zitona «

All types of Lacquers, convertible or non-convertible products require very specific type of thinner. A company that formulates the paint system, for reasons of Patent knowledge, may not reveal the exact formulation. So it is very necessary to use the thinner specified by the manufacturer. A thinner is a combination of different solvents. There are two important considerations, action of dissolving and diluting (acting as a carrier), and evaporation rates of the solvents. A Lacquer system may need as much as 75% or more thinners for spray like application. But after the deposition on the surface, it does not require such low viscosity. So some solvents (usually diluent or carrier) begin to evaporate very quickly. Some other slower evaporating solvents, allow time for film to level out.

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Lacquer coated Brass

A lacquer-thinner is a combination of solvents of basic Five groups. First group consists of latent solvents like Toluene, xylene and naphtha. The other three groups are of active solvents such as, ketones, esters, glycol ethers. Alcohol, though a latent solvent, in combination with other solvents plays an active role.

Lacquer thinners are affected by the weather and process of application. A normal thinner works for average temperature-moisture conditions. For very wet, windy weather and for brushing or manual polishing with a cloth bundle, reduced the rate of evaporation achieved by adding or using a ‘retarder thinner’. For spray like application, an accelerated rate of drying is possible and for this accelerator or fast lacquer thinners are used. Spray applications require more and faster drying thinner compared to wood lacquers that require less and slow drying thinner.

Channapatna-toys

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Shellac finishes were the first true clear coatings. Shellac is an insect exudate known as stick lac. Stick-Lac is refined to remove impurities and lighten its colour. Button-Lac is a manually purified is of darker colour, while machine purified shellac is often dewaxed and de-colourized. Shellac is soluble in methylated spirit or alcohols. Sankheda 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.

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