paints

Paints, Distempers, VarnishesFor protection and good appearanceDifferent layers – priming, base coat, first coat, second coat etc.

Components

A base pigment - forming the bulk of the paint, gives durability & protection due to resistance to the elements. Depending on the material of application, eg – white lead for wood, red lead for steel etc.

A vehicle or binder - Facilitating the spread of the paint and bind the paint and surface together. Eg- oils like linseed oil, resins, bitumen, cellulose derivatives etc.

A solvent or thinner - Determines the viscosity. Eg- turpentine in oil paints or water in emulsion paints.

A drier - Accelerating the process of drying of the paint. Eg – cobalt, lead, manganese etc dissolved in volatile liquids.

Colouring pigments - Added to give colouring.

Paints, Distempers, Varnishes

Commonly used paints• Oil paints/oil based paints – base, oil binder and thinner• Enamel paints – based on solvents like synthetic alkyl resins• Emulsions – water based coating, textured as well as plastic variants• Distempers – water based and chalk base paints• Cement paints – white cement as common base• Primers – coatings used for surface preparation before paint application• Varnishes – transparent or nearly transparent solutions of resins

Paints, Distempers, Varnishes………….

Classification• According to the nature of the binder – oil in oil paint• The way it dries to form the protective coating – enamel paint• According to its use – anti corrosive paint• According to its main component. – bitumen in bituminous paint

Pigment Volume Concentration NumberPVCN = Volume of base pigment / volume of non volatile vehicle in the paint

Considerations in choosing paints• Nature of the surface to be painted• Moisture in the material to be painted• Alkalinity of the surface• Relative humidity of atmosphere at time of painting• The purpose of using the paint• Cost of the paint• Colour of the paint


Commonly used paints

Cement paintsWhite cement, colouring pigments, accelerators and other additivesAllows walls to breath. Normal cement paints need curing. Eg- snowcem, supercem etc- can be applied on damp walls- Other paints can be subsequently painted over it.- Requires less skill- Alkalinity of walls does not affect the paint.

Oil paintsBase and vehicle components composed of oilForms a non breathing membrane.

Enamel paintsMetallic oxides, oil, petroleum and natural resinous matterMostly used for metal and wood.


Commonly used paints……….

Synthetic Enamel paintsOil modified alkyl resin medium.Greater durability and corrosion resistance.

Plastic emulsion paintsA liquid having fine suspended particles.Synthetic resins, pigments, other soilds and water.Plastic emulsion – plastic compounds like vinyl acetate and acrylate.Very popular – ease in application, quick drying property, good workability, and no objectionable odour.

Application – for interiors and plastered walls.- Smooth finished surface preparation using putty- Preferably dry walls- 2 coats, 2nd coat to be thicker than 1st.



Exterior paintsAppearance as well as ability to withstand the elements, fungus, mould etc.Water proof and long lastingAcrylic paints, some with claimed reflective properties.Surface preparation including repairing surface damages important.

Whitewash/ColourwashObtained from fat lime prepared using shell lime or lime stone.Colouring pigments added as required.

High build paint coatingsGlazed appearanceCompound of Urethane polyesters and epoxies or an emulsion based with acrylic lacquer.



DistempersPowdered chalk base with glue, resin or acrylic as the binder and water as carrier.Ordinary, dry (powder form) or oil bound distemper (oil based but water soluble)

Paint primersTo fill the minute pores of surface to be painted.To chemically prepare - alkali resistant wall primer to neutralize lime.Cement primer, wood primer, steel primer etc.

VarnishesSolution of resin or resinous substances in alcohol or turpentine.Resins like shellac, lac etcSolvents like methylated spirit, wood naptha etcDriers like litharge, white copper, lead acetate etc.

Types – oil varnishes, spirit varnishes, turpentine varnishes and water varnishes.


Covering capacity of paintsDefined as the area in square meters that can be covered by one litre of paint one kg of paint.Varies from Cement paint (2-4 sqm/kg) to plastic emulsion (22-25 sqm/litre)


Application procedure – DistemperingAccording to Indian standard Dry Distemper (IS: 427-1965) is water based wall paint but its binders may be natural or synthetic (acrylic).

Preparation of New SurfaceNewly plastered surfaces are allowed to dry for at least two months before the application of distemper. The surface is brushed thoroughly to make it free from mortar droppings. Then the sand paper is rubbed to make the surface smooth. Preparation of Old SurfaceAll loose pieces and scales are removed by sand papering.The surface is cleaned of all grease, dirt, etcHoles in plaster are filled in with Plaster of Paris mixed with color.Then the surface is rubbed down again with fine grade sand paper to make it smooth. A coat of distemper is applied on patches. The patched surface is allowed to dry thoroughly before applying regular coat of distemper.


Priming CoatA priming coat of approved primer is applied over prepared surface in case of new work. No white washing coat is used as priming coat for distemper. The treated surface is allowed to dry before applying distemper coat.

Application on New Construction After the application of primary coat two or more coat of distemper should be applied till the surface shows an even colour. Application on Old WorkOne or more coats of distemper should be applied on the surface till the surface attains an even colour.Procedure of ApplicationThe entire surface should be coated with proper distemper brushes in horizontal strokes uniformly followed by vertical ones immediately.The subsequent coats should be applied only after the previous coats are dried. The finished surface should be even and uniform showing no brush marks.Enough distemper should be mixed to finish one room at a time.


Application procedure – Painting metals

New, ferrous metal (e.g. steel, cast iron). Remove all traces of grease and oil using white spirit or other suitable solvent. Clean the surface with wire brush and brush off. Apply a suitable metal primer. Lightly rub down with sand/emery paper and brush off. One undercoat. Two gloss coats.

Rusted ferrous metal Remove all rust and rub down. Apply a suitable anti-rust treatment. Apply suitable metal primer. Lightly rub down with sand/emery paper and brush off. One undercoat. Two gloss coats.

Referhttp://www.jnpaints.com/intrior-paintg-process.phphttp://www.jnpaints.com/metal-surface-painting.phphttp://www.jnpaints.com/wood-surface-painting-process.php

http://www.jnpaints.com/intrior-paintg-process.php

http://www.jnpaints.com/metal-surface-painting.php

http://www.jnpaints.com/wood-surface-painting-process.php

http://www.jnpaints.com/wood-surface-painting-process.php

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