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P A I N T S A N D C O A T S
MAITREYI YELLAPRAGADA NEELAKSHI RATHORE
Cave paintings drawn with red and yellow ochre, hematite, manganese oxide, and charcoal may have been made by early Homo sapiens as long as 40,000 years ago. The Egyptians mixed their colors with some gummy substance, and applied them separated from each other without any blending or mixture. They appeared to have used six colors: white, black, blue, red, yellow, and green. They first covered the field entirely with white, upon which they traced the design in black, leaving out the lights of the ground color. They used minium for red, and generally of a dark tinge. Paint was made with the yolk of eggs and therefore, the substance would harden and stick onto the surface applied. Pigments
Pigment Binder or vehicle Solvent Driers Additives Inert fillers
Granular solids incorporated into the paint to contribute color, toughness, texture or simply to reduce the cost of the paint. Alternatively, some paints contain dyes instead of or in combination with pigments. Classified as either NATURAL OR SYNTHETIC TYPES. Natural pigments - clays, calcium carbonate, mica, silicas, and talcs. Synthetics - engineered molecules, calcined clays, blanc fix, precipitated calcium carbonate, and synthetic silicas. Hiding pigments, in making paint opaque, also
Some pigments are toxic, such as the lead pigments that are used in lead paint. Paint manufacturers began replacing white lead pigments with the less toxic substitute, titanium white (titanium dioxide), even before lead was functionally banned in paint for residential use in 1978 by the U.S. Consumer Product Safety Commission: The titanium dioxide used in most paints today is often coated with silicon or aluminum oxides for various reasons such as better exterior durability, or better hiding performance (opacity) via better efficiency promoted by more optimal spacing within the paint film.
Binder or vehicleThe binder, commonly referred to as the vehicle, is the actual film forming component of paint. It is the only component that must be present; other components listed below are included optionally, depending on the desired properties of the cured film. The binder imparts adhesion, binds the pigments together, and strongly influences such properties as gloss potential, exterior durability, flexibility, and toughness. Binders include synthetic or natural resins such as acrylics, vinyl-acrylics, vinyl acetate/ethylene (VAE), polyurethanes, polyesters, melamine resins, epoxy, or oils. Binders can be categorized according to drying, or curing mechanism. The four most common are simple solvent evaporation, oxidative crosslinking, catalyzed polymerization, and coalescence.
Adjust the curing properties and viscosity of the paint. It is volatile and does not become part of the paint film. It also controls flow and application properties, and affects the stability of the paint while in liquid state. Carrier of the non volatile components. In order to spread heavier oils (i.e. linseed) as in oil-based interior housepaint, a thinner oil is required. These volatile substances impart their properties temporarilyonce the solvent has evaporated or disintegrated, the remaining paint is fixed to the surface. This component is optional: some paints have no diluent. Water is the main diluent for water-borne paints. Solvent-borne, also called oil-based, paints can have various combinations of solvents as the diluent, including aliphatics, aromatics, alcohols, ketones and white spirit. These include organic solvents such as petroleum distillate, esters, glycol ethers, and the like.Sometimes volatile low-molecular weight synthetic resins also serve as diluents. Such solvents are used when water resistance, grease resistance, or similar properties are desired.
Acts as a catalyst in the drying process Makes paint hard Eg lead acetate, magnesium sulphate.
Control foam, Enhance adhesion, Improve wetting, leveling and flow, Resist moisture, Impart slip and gloss, Improve mar resistance, Help prevent pigment separation Usually added in very small amounts and yet give a very significant effect on the product. Some other examples include additives to modify surface tension, improve flow properties, improve the finished appearance, increase wet edge, improve pigment stability, impart antifreeze properties, control foaming, control skinning, etc. Other types of additives include catalysts, thickeners, stabilizers, emulsifiers, texturizers, adhesion promoters, UV stabilizers, flatteners (de-glossing agents), biocides to fight bacterial growth, and the like.
Fillers are a special type of pigment that serve to thicken the film, support its structure and simply increase the volume of the paint. Fillers are usually made of cheap and inert materials, such as diatomaceous earth, talc, lime, baryte, clay, etc. Floor paints that will be subjected to abrasion may even contain fine quartz sand as a filler. Not all paints include fillers. On the other hand some paints contain very large proportions of pigment/filler and binder.
Color changing paint
Various technologies exist for making paints that change color. THERMOCHROMIC PAINTS and coatings contain materials that change conformation when heat is applied, and so they change color. Liquid crystals have been used in such paints, such as in the thermometer strips and tapes used in fishtanks. PHOTOCHROMIC paints and coatings contain dyes that change conformation when the film is exposed to UV light, and so they change color. These materials are used to make eyeglasses. ELECTROCHROMIC paints change color in response to an applied electric current. (Car manufacturer Nissan has been reportedly working on an electrochromic paint for use in its vehicles, based on particles of paramagnetic iron oxide. When subjected to an electromagnetic field the paramagnetic particles change spacing, modifying their color and reflective
PRIMER: is a preparatory coating put on materials before painting. Priming ensures better adhesion of paint to the surface, increases paint durability, and provides additional protection for the material being painted. It can also be used to block and seal stains, or to hide a color that is to be painted over.
EMULSION PAINT: is a water-based paint used for painting interior or exterior surfaces.VARNISH AND SHELLAC: provide a protective coating without changing the color. They are paints without pigment.
WOOD STAIN: is a type of paint that is very "thin," that is, low in viscosity, and formulated so that the pigment penetrates the surface rather than remaining in a film on top of the surface. Stain is predominantly pigment or dye and solvent with little binder, designed primarily to add color without providing a surface coating.
LACQUER: is usually a fast-drying solvent-based paint or varnish that produces an especially hard, durable finish.An ENAMEL PAINT is a paint that dries to an especially hardness, usually glossy, finish. Enamel paints sometimes contain glass powder or tiny metal flake fragments instead of the color pigments found in standard oil-based paints. Enamel paint is sometimes mixed with varnish or urethane to increase shine as well as assist its hardening process. A GLAZE is an additive used with paint to slow drying time and increase translucency, as in faux painting and Art Painting. A ROOF COATING is a fluid applied membrane which has elastic properties that allows it to stretch and return to their original shape without damage. It provides UV protection to polyurethane foam and is widely used as part of a roof restoration system.
FINGER PAINT: is a kind of paint intended to be applied with the fingers; it typically comes in pots and is used by small children, though it has very occasionally been used by adults either to teach art to children, or for their own independent use. INKS are similar to paints, except they are typically made using finely ground pigments or dyes, and are designed so as not to leave a thick film of binder. ANTI GRAFFITI PAINTS are used to defeat the marking of surfaces by graffiti vandals. There are two categories, sacrificial and non-bonding. Sacrificial coatings are clear coatings that allow the removal of graffiti, usually by pressure washing the surface with highpressure water, removing the graffiti, and the coating (hence, sacrificed). They must be re-applied afterward for continued protection. This is most commonly used on natural-looking masonry surfaces, such as statuary and marble walls, and on rougher surfaces that are difficult to clean. Non-bonding coatings are clear, high-performance coatings, usually catalyzed polyurethanes, that allow the graffiti very little to bond to. After the graffiti is discovered, it can be removed with the use of a solvent wash, without damaging the underlying substrate or protective coating. These work best when
TITANIUM DIOXIDE is extensively used for both house paint and artist's paint, because it is permanent and has good covering power. Titanium oxide pigment accounts for the largest use of the element. Titanium paint is an excellent reflector of infrared, and is extensively used in solar observatories where heat causes poor seeing conditions. ANTI-CLIMB PAINTS is a non-drying paint that appears normal while still being extremely slippery. It is usually used on drainpipes and ledges to deter burglars and vandals from climbing them, and is found in many public places. When a person attempts to climb objects coated with the paint, it rubs off onto the climber, as well as making it hard for them to climb.
Tinting of Paint
To obtain uniform and specific colors in paints, machines are used to give color to the bases. White colored bases are used and coloring pigments are added in respective proportion and mixed uniformly.
Process of painting:
The surface should be cleaned and all the rust and the stains should be removed in case of repainting. Cracks should be filed with putty and the surface should be smoothened. Paint is applied in generally 2 or 3 coats. The first coat known as primer coat is applied horizontally with normally 4 brushes. After this dries , a second cross coat is applied. The final coat is the finishing coat.
Criteria for selection of paints:
Surface type: - plastered: rough, smooth - wood - metal Location: - interior - exterior
For Exterior plastered surfaces:
Cement paints Exterior emulsion
Examples ACE exterior emulsion APEX ULTIMA APEX weather proof exterior emulsion
For Interior plastered surfaces:
Berger Silk splendor Rangoli easy clean
Asian Royale luxury emulsion Premium emulsion
decreasing order of quality and cost
Velvet touch Dulux 3 in 1
Rangoli fashion finish
Distemper They are of 2 types Acrylic and Synthetic Are very cheap. They cannot be applied to surfaces which are prone to action of water.
For Metal / Wooden surfaces:
Enamels: Premium gloss enamel Premium satin enamel
Automotive paints:These are used for automobiles, cupboards, appliances etc. They are classified as: Synthetic base Nitro cellulose base Poly urethane base Stoving enamel Companies- aspa, cellocoat, PPG, Sicons etc.
Process of application of automotive paints:
Application of primer. Covering with Surfacer Levelling with Putty work Application of paintsmetallic/ non metallic PU based coating (for metallic paints)
These are used for repainting the damaged areas. These are also used for creating designs with the help of stencils. Eg BOSNY.
Powder coatings, APICL for appliances Gloss clear and flat clear coats of BOSNY ESDEE timber coat for wood finish PU based coating for automobiles. Touchwood-timber finishing.