Different types of paints used in building construction

Paint Application

The Paints, Varnishes and Distemper are provided final part of treatment to the surfaces of wall, Ceiling, floors, wood work etc. both Internally and Externally. Some more forms of Finishes/treatment are used used depending upon the modes of requirements.

These building treatments perform two major functions:

1. They Provide protective coating to the surface.This helps in preserving and protecting the materials used in building construction from Environmental effects like Heat, Frost, and Rain Water.
2. They provide decorative finish or treatment or adds aesthetic appearance to the life of building.
Objective:
After studying this Article , we should able to
a) explain the functions of paints, varnishes and distemper
b) describe the properties of good paints, varnishes and distemper
c) know the constituents of paints, varnishes and distemper
d) describe the process of painting, varnishing and distemper
e) explain the importance of their use
Paints:
Paints are used to protect metals, or plastered surfaces from the corrosive effects of weather, , moisture or gases etc. and also to improve their appearance.
Function Of Paints:
Paint Performs the Following Functions:
a) It protects wood from decaying
b) prevents corrosion of metals
c) It renders surface hygienically safe and clean
d) It gives decorative and attractive appearance to the surface
e) It also protects the surface from harmful effects of atmospheric agencies.

Characteristics of an Ideal Paint :
1) The paint should be cheap
2) It should be easy and harmless to the user
3) It should retain its original color for a long time
4) It should be able to cover maximum area of the surface with minimum quantity
5) The painted surface should dry neither too slowly nor too rapidly
6) When applied, the paint should form a thin uniform film on painted surface
7) The paint should form a hard and durable coat on the painted surface
8) The paint should not peel off from painted surface
9) It should be good fire and moisture resistant
10) The painted surface should not show any cracks
11) The painted surface should possess attractive and decorative pleasing appearance
12) Atmospheric agencies should not be able to affect the painted surface

Constituents of an Oil Paint or Oil Borne Paints:
An oil paint essentially consists of the following ingredients:
(i) A base
(ii) An inert extender or filter
(iii) A vehicle or carrier
(iv) A drier
(v) A solvent or thinner
(vi) A coloring pigment

Base:-
It provides body to the paint and on it depends upon the nature of paints to a great extent.A base in general should possess the following properties

(i) It is the solid matter forming the main body of the paint
(ii) It makes the paint film harder and more resistant to abrasion
(iii) It reduces shrinkage cracks formed on drying
(iv) It forms an opaque layer to obscure the surface of material to be painted

White lead, Red lead, Zinc oxide, Iron oxide, and metallic powders such as Aluminium, Copper and Bronze etc. are the commonly used bases

An Inert Extender or Filter 
They are added in the paint to reduce the cost and also to modify some of the properties of the paints.
They reduce weight of the paint and render paint more durable.They should not be used in excess amount as otherwise paint may loose its original character and may become weak.
Barium sulfate silica, lithophone, whiting, charcoal, gypsum silicate of magnesia or alumina etc. are the usual inert extenders.

Vehicles or Carriers 
They are liquid substances which hold solid ingredients of the paint.In general vehicles or carriers possess the following properties :
(i) It is an oily liquid in which the base and pigment are soluble

(ii) It facilitates the paint to be conveniently spread evenly over the surface by means of a brush

(iii) It acts as a binder for the base and causes it to stick to the surface

(iv) On drying, it forms a tough and an elastic film,Oils most commonly used as vehicles are linseed oil, poppy oil, nut oil and tung oil

Driers

These are metallic compounds which when added to the paint in small quantities accelerate the process of drying of the paint.Driers have a tendency to affect the color of the paint and also to destroy the elasticity of

the paint. Hence, they should not be used in excess amount. They are not used at all in final finishing coat of the paint. Driers should not be used in a paint that dries well.

Litharge, manganese dioxide, lead acetate and cobalt are the usual driers out of which litharge is most commonly used.

Solvents or Thinners 
A liquid thinner is added to the prepared paints to increase their fluidity to the desired consistency so as to make them work more smoothly and also to help penetration of porous surfaces. It evaporates after the paint has been applied to the surface.It also helps the paint in its penetration into the surface to be painted.

Turpentine oil, petroleum spirits and naphtha these are mostly used as solvents or thinners.

Coloring Pigments 

These are coloring agents which are used to develop desired shade of the paint. For white, black and other very dark shades, the base of the paint is chosen in such a way that, it will develop the color of the paint through base itself. In case of other shades, coloring pigments of desired shade are mixed with the paint. Coloring pigments may be divided into five divisions

(i) Precipitates
(ii) Natural earth
(iii) Calcined colors
(iv) Lake colors
(v) Metallic powders

There are Various coloring pigments to develop a particular color such as :

(i) Blue
(ii) Brown
(iii) Black
(iv) Green
(v) Yellow
(vi) Red

Types of Paints :-

Following are the Different Types of paint
(i) Aluminium Paint
(ii) Anti-Corrosive paints
(iii) Asbestos paints
(iv) Bituminous paint
(v) Bronze paints
(vi) Cellulose paint
(vii) Casein paint
(viii) Cement paint
(ix) Enamel paint
(x) Emulsion paint
(xi) Graphite paint
(xii) Plastic paints
(xiii) Silicate paint
(xiv) Luminous paint
(xv) Inodorous paint
(xvi) Rubber paint

Here we will study all the types in details

Aluminium Paint :- It  is prepared by holding very finely ground aluminium in suspension either in quick drying spirit varnish or slow drying oil varnish as per the requirements of the surface to be painted. The suspension liquid is spirit or oil, evaporates and a thin metallic film of aluminium is left on the surface. This paint is used for painting wood work and metal surfaces. It is widely used for painting hot water pipes, gas tanks, marine piers, oil storage tanks, radiators, etc.

Anti-corrosive Paint :- These are used mainly to protect the surface of metallic structural steel work, against the negative effects of acids, corrosive chemicals fumes etc. There are several paints which exhibit these properties. These paints essentially consist of the linseed oil, as vehicle and red lead, zinc oxide iron oxide, zinc dust, zinc chromate etc. as their base. These paints are cheap, durable and are usually black in color.

Asbestos Paint :- It is used for stopping leakage of metal roofs and painting gutters, spouts, flashing etc. to prevent their rusting. The paint is also used as damp proof coat to cover the outer face of the basement walls. This paint can withstand the effects of acidic gases and steam.

Bituminous Paint :- This paint consists of asphalt, bitumen or pitches, dissolves in any type of oil or petroleum. The paint is always black in color but its color can be modified by mixing certain pigment like red oxide etc. in it. The paint is used mostly for painting iron-works under water. These paints deteriorate when exposed to direct sun. It is also used for water proofing.

Bronze Paint  :- These  are prepared by disbursing aluminium bronze or copper bronze in nitro-cellulose lacquer as vehicle. They produce a very reflective type of surface and hence very useful for being applied on radiators. These paints are equally effective for painting interior or exterior metallic surfaces.

Cellulose Paint  :- This type of paint is prepared from cellulose sheets, nitro-cotton and photographic films. This paint dries very quickly and provides a flexible,hard and smooth surface. The paint does not harden by oxidation but by evaporation of thinning agent. The surface of the paint can be easily washed and cleaned. It remains unaffected by hot water, smoky or acidic atmosphere. This paint is used for painting cars, aeroplanes etc.

Casein Paint :- Casein is a product extracted from milk curd. Casein paint when mixed with base like whiting, titanium, lithophone, etc. forms the paint which is usually available in powder or paste form. This paint has high capacity and can be applied on new plaster work. It is usually used on walls, ceilings wall boards, cements block construction etc. to increase the appearance of the surface.

Cement Paint  :- This paint is available in powder form. It consists of white or colored cement as its base and water acts as a vehicle. No oil or varnish is added to it. This paint is available in variety of shades. It is durable and water-proof. This paint proves to be useful for surfaces which are damp at the time of painting and are also likely to remain damp after painting.

Enamel Paint :- This paint is prepared by adding base like white lead or zinc white to a vehicle which is a varnish. To obtain the desired color, coloring pigments may also be added. This paint dries slowly and forms a hard, durable,smooth, glossy, solid thin film. Enamel paints can be used both for interior as well as exterior painting.

Emulsion Paint :- This paint consists of synthetic resin like polyvinyl acetate. It can be applied easily. It retains its color for a very long time. The surface of the paint is tough and can be cleaned by washing with water. This paint has excellent resistance against action of alkali. It dries very quickly in about one to two hours.

Graphite Paint :- It is black in color. It is used over the surface which come in contact with ammonia, chlorine, sulphur gases, etc. It is very much used in under ground railways.

Plastic Paint :- This paint contains a variety of plastics in suspension and is available in the market under different trade name. It is mostly used in show rooms, display rooms, and auditorium etc. It can be applied by spray or by brush.

Silicate Paint :- It is prepared by mixing calcium and finely ground silica with resinous materials. It forms a very hard and durable film on painted surface. It can be directly applied on brick, concrete or plastered surface, but only after wetting them.

Luminous Paint :- This paint is prepared by mixing calcium sulphide with varnish. This paint shines in darkness like radium dials of watches. This paint should be applied on surface which have been rendered free from corrosion or lead paints in particular.

Inodorous Paint :- This paint consists of white lead or zinc white mixed with methylated spirit no turpentine is used in this paint. White lead or zinc white is ground in oil Shellac with same quantity of linseed oil and castor oil is dissolved in methylated spirit and this mixture is mixed with lead or zinc white paste  prepared in linseed oil. This paint dries quickly, but is not durable.

Rubber Paint  :- This paint is prepared by treating rubber with chlorine gas (chlorinated rubber) and then dissolving it in suitable solvent. This paint can be used on new concrete and lime plastered surfaces. This paint dries quickly. It is little affected by weather and sunlight. It is resistant against chemical actions water, etc.

Application of Paintings:-

Application of paint to a surface either with a brush or by spraying is known as process of painting. The surface to be painted should be perfectly smooth, clean and dry. Presence of moisture between the paint and surface to be painted or between successive coats of paints causes blisters. Painting should as far as possible be carried out in dry weather.

Brush of only good quality, the hair of which do not come off while painting,should be used.

The paint is applied on the surface in two, three or four coats. The first coat is The paint is applied on the surface in two, three or four coats. The first coat is are known as under coats.

Prime coat forms a thin film which helps in adhesion of the paint with the surface.It also protects the surface from weathering action. Materials for priming coat should be selected keeping in view the nature of the surface to be painted.

Under coats serve as foundation on to the finishing coat. These coats fill all the irregularities of the surface.

Finishing coat is lastly applied as per the requirements.

Process of Painting on plastered surface:-A plastered surface should be painted only after it has thoroughly dried, otherwise the paint would get spoiled.

The following factors should be kept in mind while painting a plastered surface :-

(i) As far as possible fresh plastered surfaces should not be painted. At least 6 months to 12 months time should be given to the plastered surface to dry completely.

(ii) Fresh plaster is alkaline in nature, because lime is liberated during the hydration of cement. Oil based paints and distemper are prone to alkali attack in the presence of moisture. Hence, if freshly plastered surface is to be painted, an alkali resistant primer paint should be applied or alternatively paints not containing any oil should be used.

Note:- Spots of plastered surface showing efflorescence should be brushed off. If spots appear again, they should again be brushed off and painting should be postponed till such spots ceases to appear.

In case of new plastered surfaces, a solution of one kilogram of zinc sulphate in two kilograms of water should be applied to the surface. When it has dried then a coat of pure raw linseed oil is applied. It is followed by two coats of paint thinned with turpentine and a little varnish. Third coat consisting of white lead, linseed oil, , desired pigment and a little oil of turpentine is then applied. Finishing coat may be the same as third coat but with a little more of turpentine oil.

However, these days paints are available in market that can be applied directly on newly plastered surfaces. These are known as cement paints.

Process of Painting on concrete surfaces:- For painting concrete surfaces, cement paints are used. They are available in powder form. They are used by mixing with water. Prepared paint should be consumed within 2 hrs or its preparation. Two coats should be applied at an interval of 24 hrs. The painted surface should be cured by sprinkling water at intervals.

Defects in Painting :- 

Various types of Defects may occur in painting work

Fading :- The paint may lose some of its color due to effects of sun rays on coloring pigments.

Flaking :- Due to poor adhesion, paint may peel off from the surface.

Grinning :- If the opacity of the final coat is insufficient, the back ground of the painted surface is clearly visible. This defect is known as grinning.

Bloom  :- Due to bad ventilation or defective paint, dull patches are developed on the painted surface.

Flashing :- This is opposite of bloom. In this defect, glossy patches are developed on the painted surface. The reason of this defect may be cheap paint, weather reaction or poor workmanship.

Blistering :- This defect occurs due to trapped moisture behind the painted surface.

Running :- This defect occurs when the surface to be painted is very smooth. in this defect, small areas of the surface are left uncovered with paint.

Sagging :- Thickness of painting should not be excessive. If too much thick coat of paint is applied, the defect is known as sagging.

Wrinkling  :- This defect occurs in thickly painted surfaces.

Reason For Failure Of Paints:-
Painting is an easy job but also has its own peculiarities.When paint applied on the surface does not perform its purposes, it is called failure of the paint.

following are the main causes of failure of paint:-

Poor Workmanship:-
Painters are generally in habit of thinning the paint too much so that he may save paint and labor both. This leads to bad workmanship and it is possible that paint may be absent for portions of surface.

Wrong Choice of Paint :-
Choice of paint is done based upon climatic conditions, nature of surface to be painted and so many other factors affecting the performance of the paint.Low quality paints are cheap but their durability is very poor.

Surface Penetration :-
If the surface to be painted has not been prepared well to receive the paint,it may lead to failure of the paint.

Moisture:-
Leakage of moisture on any painted surface accelerates the process of separating the paint layer from the surface.

Salts and Alkalies :-
The movement of moisture can also transport salts from either internal volume of masonry or new deposits. Such salts and alkalies saponify the oil paints.

Conditions for Painting :-
The painting should be done when atmospheric conditions are favorable.Dirt, dust and moisture must not get entrapped during the process of painting.