Inert filler or extender

It is a cheap pigment added in a paint to reduce its cost.in addition, it modifies the wait of the paint and makes it more durable. the commonly used inert fillers or extenders are barytes (barium sulphate), lithopone, silica, silicate of magnesia or alumina, whiting, gypsum, charcoal etc..

Coloring pigments

As the name indicates, it is a white or coloured pigment, mixed in a paint to get the desired color of the paint.

Vehicle

It is a liquid which acts as a binder for the various pigments, viz., bases, extender and coloring pigment, the vehicle makes the paint in the states of fluid thus helps to spread its ingredients’ uniformly over the surface to be painted. Refined linseed oil is a commonly used vehicle in oil paint. Tung, perilla, soybean, fish, sunflower, tobacco seeds are also being used as vehicles in various combinations with linseed oil or without linseed oil

Solvent or thinner

It is a liquid which thins the consistency of the paint and evaporates after the paint film as been applied.it imparts to the paint film good properties such as brush ability, smoothness and easy flow. Turpentine’s, pure oils, petroleum sprit and highly solvents naphtha are commonly used solvent or thinner

Drier

These are materials containing metallic compound and are used in small quantities for accelerating the driving of paint films. They act as catalysts for the oxidation and polymerization of the vehicle used in the paint. Litharge, lead acetate, manganese dioxide and cobalt are the driers should be used in a oil paint. If used in excess, especially in the final coat, they tend to destroy the elasticity of paint which finally leads to its flaking.

Characteristics of good paint

A good paint should have following Characteristics

It should stick well to the surface and should be able to seal porous substrata.

The consistency should provide easy workability.

The thickness of paint film should be adequate for good protection and decoration of surface.

The paint film should dry rapidly.

The dried paint film should be able to withstand the adverse weather affect for a long time without using gloss.

It should offer a resistance to the failure by checking, cracking, flacking.

It should possess good moisture resistance.

Its color should not fade with passage of time.

Coloring pigments

coloring pigments are used to give desired colors to the paint. In general, for white, black and very dark shades, the base itself is chosen to be color pigment. In case of light or bright color, the desired shade is obtained by mixing it to the white paint.

The coloring pigments generally used are

Black pigments: a lampblack, vegetable black, ivory black, graphite.

Brown pigments: raw amber, burnt amber, burnt sienna, Vandyke brown.

Blue pigments: Prussian blue, indigo, ultra marine blue, cobalt blue.

Yellow pigments: chrome yellow, yellow ochre, zinc, chromates, barium chloride, sienna.

Red pigments: Indian red, carmine red, red, lead, vermillion, venetian red, Tuscan red.

Green pigments: verdigris, green earth, chrome green, emerald green

Types of paints

The various type of paints commonly used can be divided as follows

1. aluminum paints

2. Anti-corrosive paints

3. asbestos paints

4.bituminous paints

5. bronze paints

6. cellulose paints

7. casein paints

8.cement based paints

9. enamel paints

10.oil paints

11. rubber based paints

Bases for paint

1.white lead –this is a carbonate of lead and it forms the base of lead paints.it possesses good bulk and is the most widely used base.it is dense, permanent and water-proof.it is not suitable for wood surfaces and not used for iron surfaces it does not afford protection against rusting.

2.red l

Vechicles:the vehicles are the liquid substances which hold the ingredients of paint in liquid suspension. They are required mainly for two reasons:

1)to make it possible to spread the paint evenly and uniformly on the surface in the form of a thin layer; and

2)to provide a binder for the ingredients of a paint so that they may stick or adhere to the surface.

Driers: these substance accelerate the process of drying. A drier absorbs oxygen from the air and transfers it to the lined oil, which in turn, gets hardened.

The various patented driers are available in the market. They may be either in the form of soluble driers. The former driers are compounds of metal such as cobalt, lead, manganese, etc. Dissolved in linseed oil or some other volatile liquid. The inert fillers serve as adulterants and the weight of inert filler in a paint should not exceed one-fourth the weight of base.

They are used for the following purposes:

a.to bring down the cost of paint;

b.to improve the durability of paints;

c.to modify the weight of paints; and

d.to prevent shrinkage and cracking.

4.colouring pigments: when it is desired to have a different colour than the base of paint, a coloring pigment is to be added. The pigments are available in the form of fine powders in various colours and qualities. Following are five divisions of the coloring pigments:

Tin of paint pigments

Black- graphite, lamp black, ivory black, vegetable black

Blue-indigo, Prussian blue

Brown-burnt umber, raw umber

Green-chrome green, copper sulphate

Red-carmine, red lead, vermilion red

Yellow-chrome yellow, raw sienna,yello orchre,zinc chrome.

5.solvents:the function of solvent is to make the paint thin so that it can be easily applied on the surface.it also helps the paint in penetrating through the porous surfaces. The most commonly used solvent is the spirit of turpentine.

A solvent or thinner is not generally used in finishing coats on the exposed surface is to be exposed to the surface as it has a tendency to impair or damage or injure the firmness of the paint.

Types of paints

1.aluminium paint: the very finely ground aluminum is suspended in either quick-drying sprit varnish as per requirement. The sprit or oil evaporates and a thin metallic film of aluminum is formed on the surface.

The advantages of an aluminum paints are:

a)it is visible in darkness.

b)it resists heat to certain degree.

c)the surface of iron and steel are better protected from corrosion by this paint than any other paint.

d)it possess a high covering capacity. A liter of paint can cover an area of about 200m2

e)it gives good appearance to the surface.

f)it is impervious to the moisture

g)it possess high electrical resistance.

The aluminum paint is widely used for painting gas tanks, hot water pipes, marine piers, oil storage tanks, radiators, etc.

2.anticorrosive paint: this paint essentially consist of oil and a strong drier. A pigment such as chromium oxide or lead or zinc chrome is taken and after mixing it with some quantity of very fine sand, it is added to the paint. The advantages of an anticorrosive paints are as follows:

a.it is cheap.

b.it lasts for a long duration.

the appearance of the paint is black.

3. asbestos paint: this is a peculiar type of paint and it is applied on the surfaces which are exposed to the acidic gases and stream.

4. bituminous paint: this paint is prepared by dissolving asphalt or mineral pitches or vegetable bitumen in any type of oil or petroleum. A variety of bituminous paints is available. The paint present a black appearance and it is used for painting ironwork under water.

5.cellouse paints: this paints is prepared from nitro-cotton,celluloids sheets, photographic films,etc.a cello use paint hardens by evaporation of thinning agent.it is a little more costly, but it presents a flexible, hard and smooth surface. Also the surface painted with cellulose paint can be washed and easily cleaned.

6.cement paint: this paint consist of white cement,pigment,accelerator and other additives.it is available in dry powder form. The cement paint is available in variety of shades and it exhibits excellent decorative appearance.it is water-proof and durable. For external finish, on cement-plastered walls, it is mixed with water immediately before its application.it is desirable to provide cement paint on rough surface rather than on smooth surface because its adhesion power on smoothly finished surface.

The cement paint is applied in two coats.

Following are the advantages of cement paints:

a)it requires less skills and time for applying cement water paints and the applying implement can be cleaned with water only.

b)the preparation of surfaces is easiers in a cement paint system as it is not necessary to remove the previous coats of cement paints.

c)they are suitable for painting fresh plasters having high alkalinity because cement paints are not likely to be attacked by the alkalinity of masonry surface.

d)they become an integral part of the substrata and add to its strength.

e)they prove to be economical as compared to the oil paints and they dry more rapidly than the oil paints.