BUILDING CONSTRUCTION

1. WALL FINISHES (PLASTERING,
POINTING & PAINTING)
S.S.A.S.I.T, SURAT GTU

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Plastering is a process of obtaining smooth surface on the rough
surfaces of walls, roofs, columns and ceilings etc. for long lasting
purposes and to meet its estimated design life period.
The coat formed on the rough surface is called plaster when applied
inside of the building and it’s called as rendering when applied
outside of the building i.e. at outer wall exposed to direct
environmental condition.
INTRODUCTION

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OBJECTSOF PLASTERING
1. To obtain an even, smooth, regular, clean and durable surface.
2. To conceal defective workmanship and covers up and cheap
quality material.
3. To provide a satisfactory base for decorating the surface by
white washing, colour washing, distempering or painting.
4. External plastering known as rendering is done to protect the
external surfaces against penetration of rain water & other
atmospheric agencies.

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Requirements of good plaster
1. It should be hard & durable.
2. It should possess proper workability.
3. It should be possible to apply it during all weather conditions.
4. It should protect the external surfaces from rain water.
5. It should be cheap.

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Types of mortars for plastering
• Mortar
 A mortar is a homogeneous plastic mixture, obtained by
process of uniform mixing of binding material, fine aggregates,
water to make a paste of required consistency & used to bind
a masonry unit.
 The various types of mortars used for plastering are as follows:
a) Lime mortar
b) Cement mortar
c) Lime cement mortar

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a) Lime mortar: The mortar used for lime plaster is prepared by
mixing lime & sand in the proportion of 1:2, 1:3 or 1:4.
b) Cement lime mortar: The mortar used for cement plaster is
prepared by mixing cement & sand in the proportion of 1:4 to
1:6.
c) Cement lime mortar: The proportion used for cement lime
plaster may vary from 1:1:6 to 1:2:9...

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METHODS OF PLASTERING:
There are basically three types of plastering i.e. lime plaster and
cement plaster or combination of both. Before plastering, however, the
back ground should be prepared since the adhesion of plaster is highly
affected by the back ground. Hence at first back ground is prepared.
•Preparation of Background:
•All masonry joints should be raked 10 mm in case of brick masonry and
15 mm in case of stone masonry for providing key to the plaster before
onset of plastering operation.
•All mortar drops, dusts and freshly laid concrete or laitance should be
removed with the help of a stiff brush. Rendering is applied after any
existing unevenness is removed.

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•For a three coat finishes the local projection should not be more
than 10 mm and local depression should not exceed 20 mm. For two
coat plaster these limitations are reduced to 5 and 10 mm
respectively.
•The surface should be kept damp for suction and it should be
cleaned 1st.The surface should not be kept soaked and neither it
should be kept less wet so as to cause strong suction which
withdraws the water from mortar and makes it weak and porous.
•During the application of plaster on old surface, all dirt, oil, paint etc
should be removed along with complete removal of all loose and
crumbling plaster to its full thickness. The back ground of the plaster
should be exposed clearly before new plaster is applied. The surface
should be kept damp to maintain optimum suction.

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LIME PLASTER
After preparation of back ground, lime plaster is applied in three
coats normally. However, two coats of plaster may be applied too.
They are discussed as follows:
1. Three Coat Plaster:
Rendering coat: This is the very first coat applied to the back
ground and its thickness is normally of 12 mm. However, this
thickness may increase as per surface unevenness. This plaster
coat covers all the irregularities and is pressed against the wall
forcibly by the help of trowel. This coat is allowed to harden for
seven days and cured well. The surface is already made scratched
just after the work is over and the surface is little bit set.

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Floating coat: The rendering coat is cleaned and the floating is
applied. Then the patches of 15cm × 15cm or 10 cm wide strip is
made for acting as gauge followed by throwing of mortar with the
help of mason’s trowel which is later spread with the help of
wooden float. which is cured for 10 days approximately to obtain a
set surface.
Finishing coat: As discussed above, the finishing coat follows
immediately after the floating coat while in case of lime-surkhi
plaster, it’s applied after getting a set and little hard surface. The
lime cream to cement ratio is kept 4:1 in finishing coat which is
applied with the steel trowel and made smoothen. The surface is
left for one day for drying and then cured for seven days.

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Two Coat Plaster:
This is nothing but combination of all three coats but the rendering
and floating coat is applied at a time with out any gap in between the
operation. Also the thickness of the combined coat is kept 12 mm
and the finishing coat is finished thereafter.

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CEMENT AND CEMENT-LIME PLASTER
1. Two Coat Plaster:
•The back ground is prepared by raking the surface up to 20 mm
depth, followed by cleaning operation of the surface and watering it.
•For very uneven surface, a preliminary coat is applied to even it and
to fill the voids.
•The 1st coat or rendering coat is applied which thickness is equal to
the specified thickness of plaster less 2 to 3 mm. In order to maintain
uniformity, screeds are formed on the surface by fixing dots of size 15
cm × 15 cm where vertical line spacing of 2m is kept in between
them.

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•The final coat may be of 2-3 mm thickness. Before application of
the final coat, the rendering coat is damped evenly. The final coat is
applied with a float and finishing is done using trowel. The coat
should be done from top to bottom and should be done in one
single operation to eliminate the joint marks.

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Three Coat Plaster:
Three coat plaster is quite similar to that of three coat plaster of lime
mortar. The procedure of applying the three coat plaster is same as two
coat plaster except one intermediate coat or floating coat is applied. Its
purpose is to bring the plaster surface in to more even and more
protection to the plaster surface. Hence it’s generally done on the outer
surfaces. The thickness of rendering, floating, and finishing coat is 9-12,
6-9 and 2-3 mm respectively which may be revised as per the
requirements. The floating coat is applied 4-7 days after applying the 1st
coat. The finishing coat may be applied after 6-7 hours of application of
floating coat.
Single Coat Plaster:
This is applied for inferior works. It’s same as two coat plaster except the
finishing coat. The rendering coat after sufficiently hardens become the
1st and final coat. The rendering coat therefore should be polished and
made even with high quality of workmanship.

15. PLASTER ON LATH
Lathing may be either of wood or that of expanded metal.
Wooden lath consists of thin strips of well seasoned wood, about
25mm .in width and 90 to 120cm.

16. PICTURE OF LATH PLASTER

17. STUCCO PLASTERING
• This is special type of plaster.
• Stucco is the name given to a decorative type of plaster which
provides an excellent finish like that with marble lining.
• After preparing the surface, stucco plastering is applied in three
coats.
• Each coat should be permitted to dry thoroughly before applying
the next coat.

18. STUCCO PLASTERING (-ctd-)
• For internal surface, the first coat also known as scratch coat
consists of lime plaster 12 mm in thickness.
• The second coat or brown coat consists of rich lime plastering in
10 mm thickness.
• The final coat or finishing coat consists of a mixture of very fine
lime and white ground stone ( marble or quartz), 3 mm in
thickness.
• It is carefully polished with a bag of linen containing moist chalk
in the first instance and then chalk and oil.
• The surface is then finally finished by rubbing it with only oil as to
make it smooth and bright.

19. STUCCO PLASTERING (-ctd-)
• For external surfaces, the first and second coats are 10 to12
mm thick and the finishing coat is 3 to 6 mm thick.
• The proportion of ingredients for the first two coats is 1 part of
cement to 3 parts of sand with 10% by weight of hydrated
lime.
• The finishing coat consists of 1 part of cement and 2 pars of
sand in which some coloring pigment is added or colored
cement is used.

20. STUCCO PLASTERING (-ctd-)
• Method of applying this plaster is same as described in case of
cement or lime plastering.
• Suitability
This type of plastering is suitable for external as well as
internal surfaces of buildings to provide an excellent finish.

21. PICTURE OF STUCCO PLASTER

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TYPES OF PLASTERING:
Following types of plastering is generally adopted in practice. Most of
them are termed as per their finishing. Others are as per their number of
coats and resisting capacity. They are described as below.
Smooth cast plaster or plain face plaster
•This finish is just similar to sand faced finish except fine grained sand is
used instead of coarse grain sand and the ratio of cement to sand is
kept 1:3.
•In this case no sponging is done since sand grains are required to be
exposed. It is normally done on internal walls.
•For external walls, steel float is not used; instead wooden float is used
as steel float provides excessive smooth surface and hence the surface
may crack due to environmental conditions.

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Rough Cast Plaster or Spatter dash plaster:
•This plaster is a mixture of sand and gravel in
specified proportion which is dashed over a
freshly plastered surface.
•The plaster base consists of two coats, under
layer 12 mm thick and top layer 10 mm
thick having the cement mortar ratio 1:3. In
the final coat of this plaster, concrete is used in
the ratio of cement : sand : coarse aggregate as
1:1.5:3 (M20). The coarse aggregate is of the
range 3mm to 12mm.
•The base is made more plastic, about 10% of
hydrated lime by volume of cement shall be
added while preparation of mortar.
•This finish is water proof, durable and
resistant to racking and crazing. Hence it may
be used for external renderings.

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Pebbled dash plaster:
It is similar to rough cast finish except clean pebble of size 10 mm to
20mm are dashed against the surface so that there are laid in position by
mortar applied already. The mortar is in the proportion of 1:3 as cement:
sand.

25. Scrapped Finish
It is a finish in which the final coat after being leveled and
allowed to stiffen for a few hours. The final coat is usually
6 to 12mm thickness

26. Textured Finish
In this finish, ornamental patterns or textured surfaces are
produced by working with various tools on the freshly
applied final coat.

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•Plaster of Paris (Gypsum Plastering): Plaster of Paris is obtained from Gypsum
powder on heating it at 1600C to 1700C and is kept dry always as it gets hardened
when comes in contact with water within 3 to 4 minutes. Its general use is with lime
combination though it may be combined with other combinations also. They are
used for ornamental works, sound insulation, fire proofing, to reduce shrinkage,
finishing of wood or timber or metal floorings etc due to adhesive property to
them. A major drawback of its use is the water solubility tendency of gypsum which
should be taken care of.
• Acoustic Plaster: This is plaster of gypsum mixture with plaster to obtain a sound
proof plastering which is applied as finishing coat in two layers of 6 mm each. The
sound insulation property is due to honey combing of the coat on undergoing
chemical reaction. These are used therefore in the interior walls of auditorium,
picture halls and conference halls etc.
•Barium Plaster: Barium sulphate is used for plastering in barium plaster with
cement and sand. This is X-ray resistive and hence protects the pathologists and
others working in the X-ray room frequently.
SPECIAL MATERIALS USED IN PLASTERING

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•Asbestos Plaster: It’s the plaster where combination of cement, asbestos
and marble chips is used for plastering; resulting a marble finish which gives
an aesthetically attractive looking.
•Granite Silicon Plaster: These are costly plastering and superior in quality
due to the elastic nature of the plastering. This is aesthetically good looking
and eliminates any cracking too due to its elastic behavior. Hence in
superior finishing works, it’s used.
•Kenee’s Cement Plaster: In this type of plaster, Kenee’s cement is used
which is obtained from the calcinations of plaster of paris with alum. It has
self polishing property and takes glas like polishing. It’s also very hard and
sets in few days thus giving an ornamental look. Hence for precious or
decorative plastering, it’s used.
•Snowcrete and Colorcrete Cement: The first one is white cement while the
second one is colored cement which is used for giving a good looking
appearance to the buildings.

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DEFECTS IN PLASTERING
•Blistering of plastered surface: This is the formation of small patches
of plaster which swells out beyond the plastered surface, arising out of
late slaking of lime particles in the plaster. It may also arise due to
presence of un slaked particles in slaked lime.
•Cracking: It consists of formation of cracks and fissures on the
plastering surface due to following reasons like :
•Defective preparation of back ground
•Structural irregularities in buildings
•Discontinuity of plastered surface
•Movements in the back ground due to the thermal expansion or
rapid drying or shaking
•Movement in the plaster surface itself either due to expansion or
shrinkage or due to creep
•Excessive shrinkage caused by application of thick coat
•Faulty workmanship

30. CRACKING

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•Pooping: It’s the formation of conical hole on the plastered surface due to the
presence of some expandable materials.
•Rust stains: These are sometimes formed when plaster is applied on metal
laths due to rusting action.
•Efflorescence: This is another defect by which the whitish crystalline material
which appears on the plastered surface due to presence of salts present in the
plastering material or building material. It gives the bad appearance and even
affects adhesion during painting. It can be removed to some extent by washing
the surface continuously and by dry brushing.
•Uneven Surface: This is obtained purely due to poor workman ship.

32. • Falling out of plaster
a. The adhesion of the plaster to the back ground may not be
perfect.
b. The suction of the backing materials may not be uniform.
c. Excessive thermal changes in plaster.

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What is pointing in Construction?
The term Pointing in construction is applied to the finishing of mortar
joints in masonry (stone or brick). In exposed masonry, joints are
considered to be the weakest and most vulnerable spots from which
rain water or dampness can enter. Pointing means implementing the
joints to a depth of 10 to 20mm and filling it with better quality mortar
in desired shape.

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MORTAR:
•The pointing may be done by using different types of mortars:
I. The mortar for lime pointing may be done with lime mortar(1:2),
where 1 part lime & 2 part of sand or surkhi are mixed in a
grinding mill.
II. The mortar for cement pointing is made with CM by mixing 1
part cement & 3 part of sand.
METHOD OF POINTING:
 The Mortar is pressed into the raked joints with a pointing
trowel & made flush, sunk or raised according to the type of
pointing required.
 The pointing lines should be regular, truly horizontal & vertical.
In case of random rubble masonry, where the joints are
slanting, the lines should meet at or near the junctions.
 The pointing should be kept wet for about a week.

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Types of pointing
•Flush pointing
•Recessed pointing
•Beaded Pointing
•Struck Pointing
•Rubbed, keyed or grooved pointing
•Tuck Pointing
•V- pointing
•Weathered pointing

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Flush pointing:
In This type of pointing mortar is pressed hard in the raked joints and by
finishing off flush with the edge of masonry units. The edges are neatly
trimmed with trowel and straight edge. It does not give good appearance.
But, flush pointing is more durable because of resisting the provision of space
for dust, water etc., due to this reason, flush pointing is extensively used.
In case of recessed pointing mortar is pressing back by 5mm or more from the
edges. During placing of mortar the face of the pointing is kept vertical, by a
suitable tool. This type of pointing gives very good appearance.
Recessed pointing:

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Beaded pointing:
It is a special type of pointing which is formed by a steel or ironed with a
concave edge. It gives good appearance, but it will damage easily when
compared to other types.
Struck pointing:
This is a modification of flush pointing in which the face the pointing is kept
inclined, with its upper edge pressed inside the face by 10mm. struck pointing
drains water easily.

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Rubbed, keyed or grooved pointing:
This pointing is also a modification of flush pointing in which groove is formed
at its mid height, by a pointing tool. It gives good appearance.
Tuck pointing:
In case of tuck pointing mortar is pressed in the racked joint first and
finishing flush with the face. While the pressed mortar is green, groove or
narrow channel is cut in the center of groove which is having 5mm width
and 3mm depth. This groove is then filled with white cement putty, kept
projecting beyond the face of the joint by 3 mm. if projection is done in
mortar, it is called bastard pointing or half tuck pointing.

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V- Pointing:
This pointing is formed by forming V-groove in the flush-finishing
face.
Weathered pointing:
This pointing is made by making a projection in the form of V-shape.

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 PAINTING:
PAINT & PAINTTING:
• The paints are the liquid composition of pigments & organic-binders, when
applied on timber, metal & plastered surfaces, on drying, forms a thin film to
provide a decorative finish & protection o the painted surface.
• Painting on masonry & concrete surfaces may resist checking & disintegration,
which increase the life of structure.
• Painting on metal surfaces at suitable intervals may prevent the metal surfaces
from corrosion.
 CONSTITUENTS OF A PAINT:
 The various constituents of a paint are as follow:
I. A base
II. A colouring pigment
III. A binder or a vehicle
IV. A solvent or thinner
V. A drier

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1. Bases: It is a principal constituent of paint. It also possesses the
binding properties. It forms an opaque coating. Commonly used
bases for paints are white lead, red lead, zinc oxide, iron oxide,
titanium white, aluminium powder and lithopone. A lead paint is
suitable for painting iron and steel works, as it sticks to them well.
However it is affected by atmosphere action and hence should
not be used as final coat. While zinc forms good base but is
costly.
2. Vehicles: The vehicles are the liquid substances which hold the
ingredients of a paint in liquid suspension and allow them to be
applied on the surface to be painted. Linseed oil, Tung oil and Nut
oil are used as vehicles in paints. Of the above four oils, linseed
oil is very commonly used vehicles. Boiling makes the oil thicker
and darker. Linseed oil reacts with oxygen and hardens by
forming a thin film.

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3. Pigment: Pigments give required colour for paints. They are fine particles
and have a reinforcing effect on thin film of the paint. The common pigments
for different colours are:
Black—Lamp black, suit and charcoal black.
Red—venedion red, red lead and Indian red.
Brown—burned timber, raw and burned sienna
Green—chrome green, copper sulphate.
Blue—prussian blue and ultra marine
Yellow—ochre and chrome yellow.
4. The Drier: These are the compounds of metal like lead, manganese, cobalt.
The function of a drier is to absorb oxygen from the air and supply it to the
vehicle for hardening. The drier should not be added until the paint is about
to be used.
5. The Thinner: It is known as solvent also. It makes paint thinner and hence
increases the coverage. It helps in spreading paint uniformly over the surface
Terpentine and neptha are commonly used thinners. After paint applied,
thinner evaporates and paint dries.

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• CHARACTERISTIC OF A GOOD OR IDEAL PAINT:
 The various characteristics of a good paint are as follows:
I. It should stick properly to the surface & seal the porous substrata.
II. It should provide adequate protection & decoration to the surface.
III. It should be readily available & economical to use.
IV. It should dry rapidly.
V. It should not possess cracks, flakes on drying.
• TYPES OF PAINTS:
I. Aluminium paint
II. Anti corrosive paints
III. Asbestos paints
IV. Bituminous paints
V. Bronze paints
VI. Cellulose paints
VII. Casein paints
VIII. Cement based paints
IX. Emulsion paints
X. Enamel paints
XI. Oil paints
XII. Plastic paints
XIII. Synthetic rubber paints
XIV. Silicates paints

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1. Oil Paint: These paints are applied in three coats-primer,
undercoat and finishing coat. The presence of dampness while
applying the primer adversely affect the life of oil paint. This
paint is cheap and easy to apply.
2. Enamel Paint: It contains white lead, oil, petroleum spirit and
resinous material. The surface provided by it resists acids, alkalis'
and water very well. It is desirable to apply a coat of titanium
white before the coat of enamel is applied. It can be used both
for external and internal walls.
3. Emulsion Paint: It contains binding materials such as polyvinyl
acetate, synthetic resins etc. It dries in 1,5 to 2 hours and it is
easy to apply. It is more durable and can be cleaned with water.
For plastered surfaces, first a coat of cement paint should be
applied and then the emulsion paint. Emulsion paint needs sound
surfaces.

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4. Cement Paint: It is available in powder form. It consists of white
cement, pigment and other additives. It is durable and exhibits
excellent decorative appearance. It should be applied on rough
surfaces rather than on smooth surfaces. It is applied in two coats.
First coat is applied on wet surface but free from excess water and
allowed to dry for 24 hours. The second coat is then applied which
gives good appearance.
5. Bituminous Paints: This type of paint is manufactured by dissolving
asphalt or vegetable bitumen in oil or petroleum. It is black in colour.
It is used for painting iron works under water.
6. Synthetic Rubber Paint: This paint is prepared from resins. It dries
quickly and is little affected by weather and sunlight. It resists
chemical attack well. This paint may be applied even on fresh
concrete. Its cost is moderate and it can be applied easily.

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9. Cellulose Paints:
Natural cellulose is chemical treated and converted to nitrate or acetate or
to methyl of ethyl cellulose. The resultant derivative of cellulose is
dissolved in petroleum or in coaltar hydrocarbon. Plasticizer which is an
organic compound of low volatility is added to cellulose paints to improve
adherence, toughness, smoothness and elasticity of the paint film.
Compared with ordinary oil paints, this paint can be easily washed, cleaned
as it has greater hardness, elasticity and smoothness and withstand
temperature changes and hot water better.
7. Aluminum Paint: It contains finely ground aluminum in spirit or oil
varnish. It is visible in darkness also. The surfaces of iron and steel are
protected well with this paint. It is widely used for painting gas tanks, water
pipes and oil tanks.
8. Anti-corrosive Paint: It consists essentially of oil, a strong dier, lead or zinc
chrome and finely ground sand. It is cheap and resists corrosion well. It is
black in colour.

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Methods and Process of Painting on Different Surfaces
•New wood work
•Repainting Old wood surface
•New iron and steel surfaces
•Repainting of old steel and iron surfaces
•Galvanized iron surface
•Metals
•Plastered surfaces
•Painting on New Wood Work

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Following are the steps for painting new wooden surfaces:
Surface preparation
Knotting
Priming
Stopping
Under coating
Finishing
1. Surface Preparation of Wooden Works
The surface should be well cleaned without any dust, spots, greasy matter etc. The
nails used in the wood work should be punched up to 3mm below the surface. The
wood in wood work should be well seasoned and should not contain more than
15% of moisture content. The surface should be dry.
2. Knotting
Knots present in the wood may eject resins from wood. So, knots are killed or
covered in this knotting process. Knotting can be done by two ways as follows:
1. In this first method, two coats of solutions are applied on surface. First coat
consists 15g of red lead, 2 liters of water and 225 grams of glue.
After adding these three, mixture is heated and applied and left for 10 minutes.
After that second coat is applied this consists red lead ground in boiled linseed oil
and thinned with turpentine oil.

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4. Stopping
After filling all the pores of wooden surface in priming, it’s time to fill up nail holes, dents,
cracks, etc. Putty is used as the fill material. When putty is dried, then the whole surface is
rubbed with glass paper or pumice stone. This process of rubbing sown the wooden surface is
called stopping.
5. Under Coating of New Wooden Surface
In general, for good quality works, 4 coats of paints are applied (prime + under coatings +
finishing). For inferior quality works 2 to 3 coats can be used. So, under coatings are nothing
but second and third coats of good quality works which provides same look or shade as
finishing coat. For better results, enough time should be allowed for each coat.
6. Finishing of New Wooden Surface
Finishing is the last coat applied on surface which is generally applied on the under coatings. It
should be applied in smooth, uniform manner. It decides the whole final look of surface, so,
skilled workers are required for better results.
3. Priming of New Wooden Surface
Priming is nothing but applying prime coat or first coat on surface. In this case, the surface is
smoothened with abrasive paper and then first coat of paint is applied to fill all the pores in
the surface. The ingredients used in this prime coat are same as subsequent coats but the
quantity or composition ratio may vary.

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Repainting of Old Wooden Surface
• Old wood work can be repainted but the previous paint work should
be removed. The removal is more important which can be done by
many ways as follows:
1. Prepare a solution of 1 kg caustic soda in 5 liters of water and apply
on the old painted surface. When this solution is applied on the
surface, the old paint gets dissolved and removed easily.
2. Another method is, prepare a hot solution consisting of soft soap,
potash, quicklime in the ratio 1:2:1. This solution is applied on old
surface and washed with hot water.1:1 mixture of washing soda and
quick lime is prepared and applied on old paint surface and then
washed with water.
3. After applying any of the three methods described above, the
surface is ready for fresh painting. Before that the surface is rubbed
with pumice stone or glass paper and then 2 to 3 coats of paints are
applied.

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Painting of New Iron and Steel Surfaces
• Painting of iron and steel surfaces will resist the rust formation due
to weathering. Before painting the surface must be cleaned. If there is
any rust or scales, should be wiped off using steel brushes etc. stains
on surface can be washed with benzene or lime water.
• Before applying prime coat, the surface should be treated with
phosphoric acid to get better adhesive nature. Now prime coat is
applied which consists 3kg of red lead in 1 liter of boiled linseed oil.
This should be applied using brush.
• After that, two or more under coats are applied which consist 3 kg
of red lead in 5 liters of boiled linseed oil. After drying up, smooth
finishing coat of desired paint is applied.

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Repainting of Old Steel and Iron Surfaces
Repainting of steel and iron surfaces is as same as new surfaces but cleaning
of old paint is most important. Oxy acetylene flame is used to burn off the
paint surface and then it is scrapped with brushes.
Painting of Galvanized Iron Surface
• In general, Galvanized iron surface does not contain adhesive nature with
paint. So, it is difficult to apply paint on it without any special action. That
special treatment may be applying different solutions on surface.
• The solutions are 40 grams of copper acetate in one liter of water or 13
grams each of copper chloride, copper nitrate, muriatic acid and
ammonium chloride in 1 liter of water. Any one of these two solutions are
mixed in earthen vessel and applied on surface. When the surface turns into
black, then prime coat is applied after it dries, finishing coat is applied.

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Painting of Plastered Surfaces
• Painting of newly plastered surfaces is difficult because of moisture
content present in the plaster material. Heat of hydration of cement
also causes severe problems for paints especially oil based paints and
distempers are liable to alkali attack.
• To overcome this, alkali resistant primer is used in prime coat. The
plastered surface contains pores in it, and whenever the paint is
applied, liquid from the paint is absorbed by these pores which is
called as suction. The suction of surface depends upon type of paint,
prime coat composition, etc. Suction should be uniform throughout
the surface.
• So, the preparation of surface depends upon the type of paint used
on the surface.

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DEFECTS IN PAINT WORK
The defects which are commonly found in paint work are as follow.
1. BLISTERING
Formation of bubbles like shapes on the painted surface is known as blistering. The
primary cause of this defect is water vapor. When water vapor trapped under the
paint layer, it creates bubbles under the film of paint.
Blistering Defect of Paint

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2. BLOOMING
Formation of dull patches on the painted surface is known as blooming. The
primary cause of this defect is poor quality of paint and improper ventilation.
Blooming Defect of Paint

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3. FADING
When there is a gradual loss of colour from the pained surface, it is known as
fading. The main cause of this defect is the reaction of sunlight on pigments of
paint.
Fading Defect of Paint

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4. FLAKING
In this type of defect, some portion of the paint film is not sticked properly with the
surface; resulting flaking off of the paint layer. This is cause due to poor adhesion
between paint and the surface to be painted.
Flaking Defect of Paint

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5. FLASHING
Presence of glossy patches on the painted surface is known as flashing. The cause of
this defect is mainly due to poor workmanship, cheap paint or weather actions.
Flashing Defect of Paint

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6. GRINNING
If the thickness of the final coat of paint becomes very thin, the background can be
seen clearly. This is known as grinning. Poor workmanship is the main cause of this
defect.
7. RUNNING
This type of defect is seen when the surface to be painted is very smooth. In case of
smooth surface the paint runs back and leaves small areas of surface uncovered.
Running Defect of Paint

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8. SAPONIFICATION
Formation of soap patches on the painted surface is termed as saponification. Chemical
action of alkalis is the cause of this defect.
Saponification Defect of Paint
9. WRINKLING
This type of defect is more prominent when a thick layer of paint is applied on a
horizontal surface.
Wrinkling Defect of Paint

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