Paint is obtained by blending and mixing of various pigments. The colour of the paint depends on the pigment concentration. It even protect the paint after application on surface as a film, this film alter the paint life and quality to withstand heat and light radiation. Along with pigment, drying oil is used to allow pigment to be dispersed in paint mixture homogeneously it is called as vehicle. It helps the pigment to form as film. Well with the action of roller coating, spraying, dipping and brushing will help to apply paint on a surface. Paint when applied evenly it gets exposed to air and start drying this is enhanced by the drying oil. Various types of drying oil used are tall oil tung oil, caster oil; linseed oil is preferred by many paints manufactures. Linseed oil is mixed in boiled or unboiled form, but boiled works faster than unboiled form because it various the drying time by 24 hrs faster. Catalyst activity for accelerating the drying process on the surface can be done by materials like driers.
The paints properties are changed when driers are add because it changes the viscosity and thickening of the paint. It promotes film formation uniformly. Types of paints available are expoxide resin paints, distempers, emulsion paints, oil paints, metallic paints, water paints, latex paints etc.
Constituents present in various types of paints:
Exterior house paint: These type of paints generally contains components such as extenders (talc, clay, barites etc), pigments (ZnO, white lead, TiO2 etc), and thinners (mineral spirits, naphtha) vehicles (boiled linseed oil). Coloured pigments are also added in varying amounts for a light tint.
Interior wall paints: By mixing resins (casein and emulsified phenol formaldehyde resins), pigments (white and coloured pigments) and vehicle (varnish) interior decorative wall paints are made.
Fire resistant paints: It is the most useful which is developed by tremendous research and still there are up going experimental works to produce a paint which can withstand and prevent the fire accidents, so that it can stop the fire from expanding from the source to other locations. If you have a garage with inflammable stuff than better choose fire resistant type paint and even if your bike or car is the best of your choices than you should be using fire resistant paints because this paint have heat resistive property which will protect the metal surface from constant exposure to the day light heat. By the combination of borax, synthetic resins, anti-fire chemicals, ammonium phosphate and zinc borate the paint becomes unsupportive to combustion process.
Chemical resistant paints: These are neutral and do not react with any type of acidic or basic compounds they are used for coating on tankers, loader and storage tanks which will be stable even they are made in contact with the storage or handling chemicals. By blending materials like baked oleoresionous varnishes, bituminous varnishes, chlorinated rubber composition, phenolics dispersions in determined concentrations chemical resistant paints are produced.
Luminous paints: It is used for night luminous effects on the wall and mostly popular in traffic and sign board paintings. They observe the minute light and glow back which appears in dark night. Pigments such as sulphides of zinc, calcium mixed in varnish with vehicles like chlorinated rubber are combined with sensitizers.
Classification of paints used for car body painting:
External surface of the car attracts the attention of people, it is the physical view that decides the hit or flap of the car model in first look, then comes its engine, safety and power. Paint on external surface of the car do the job of protection of the car’s metal surface and most importantly its style. Topcoat colors painted on the surface are inspected by the microspectrophotometer to maintain the consistency of shades caused by the pigments during painting operation. The paints are mainly depend on the coating technique applied like,
- Acrylic Coatings: It uses acrylic in the form of enamels and lacquer, for under coats and single stages.
- Polyurethane Coatings: Urethane form resin used for basecoats and midcoats.
- Water based Coating: Presently this method is used for painting new car models because a topcoat of water-based paint is safer than solvent-based paint.