About classification of paints

1. PAINTS AND VARNISHES

2. Paints
Paints are used to protect metals,
timber, or plastered surfaces from the
corrosive effects of weather, heat,
moisture or gases etc and to improve
theirappearance.

3. Properties of paint
There are a numberof ways to judge
paint quality:
Wearability
Covering ability
Ease of cleaning
Protection of thesubstrate
Environmentally Friendly
Aesthetic
Practical and Cost Effective

4. Composition of paints
Fundamental components of anoil-
based paintare:
Base
Vehicle
Pigment
Thinner
Dryer

5. Base
Makes the paint film harderand more
resistant toabrasion
Reduce shrinkage cracks ondrying
Commonly used bases are White lead, Zinc
oxide, Iron oxide, Metallic powders were
used.Paints moreoften named after the
base as Lead paint, Zinc paint, and
Aluminumpaint.

6. The binder or resin, is the actual
film forming component of paint.
adhesion, binds the
It imparts
pigments
influences
together, and strongly
such properties as
flexibility, and toughness. , exterior
durability

7. Vehicle
Oily liquid in which the base and
pigment aresoluble
Facilitates the paint to be
conveniently spread over the
surface
commonly used as
Oils most
vehicle.

8. The main purposeof thevehicle is to
adjust the viscosity of thepaint.
It is volatileand does not become part
of the paint film.
It's main function is as thecarrier for
the non volatilecomponents.
Water is the main vehicle forwater
based paints.

9. Pigment
Pigments are materials which gives the
paint its color. In white paint the body is the
pigment. Natural pigments (natural iron
oxides, chrome oxides). Synthetic pigments
(coal tarderivatives)
Pigments impartqualities such as colorand
opacity (sometimes inappropriately called
'hiding'), and influences properties such as
glossy, film flow, and protectiveabilities.

10. Thinner
Liquid thinner is added in the paint to
Increases fluidity
Making paint moresmooth
Help penetration into poroussurfaces
Common thinner turpentine(made
by distilling gum from a number of
pine trees)

11. Dryers
to quicken the drying of
Added
vehicle
Organic salts of Iron, zinc, lead,
manganese, Ca
To accelerate the oxidation and
hardening of vehicle

12. Defects in painting
Fading:
●The gradual loss of color is known as fading.This
may bedue to theeffect of sun rays.
Flaking orPeeling
●Due to the poor adhesion, paint may peel offfrom
thesurface.
Blistering:
●This is caused by water vapour, which is trapped
behind the painted surface. It may occur due to
imperfect seasoning of timber.

13. FLAKING

14. BLISTERING

15. PEELING

16. Bloom
●The formation of dull patches on the finished
surface is known as bloom. It mayoccurdue to bad
ventilation or defectivepaint.
Running:
●The paint runs back and leaves some areas of
surface un covered. Thisdefect occurs when surface
is too thickly painted sagging willoccur.
Wrinkling
●If the horizontal surface is too thicklypainted
wrinkling will occur.

17. WRINKLING

18. LACK OF ADHESION

19. Flashing
●The patches seen on the painted
surface is known as flashing. It maybe
due to poor workmanship, weather
action, orpoorqualityof paint.
Grining:
●If the opacity of the final coat is
insufficient, the back ground of the
painted surface is clearly visible,this
is known asgrinning.

20. Efflorescence
Efflorescence or formation of white
powderydepositon walls afterpainting is
caused due to salts present in the
building material like brick and mortar,
which surface lateron.
The Solution- Give a long time gap
between plastering and painting (about6
months including one monsoon) Use
paint with a porous film like emulsions
and distempers.

21. EFFLORECENCE

22. Brush marks
Brush marks are caused due to
under-thinning of paints or due to
poor application of the final coat of
paint or due to poor quality brush.
The Solution - Ensure paint of the
right viscosity is applied using a
good brush.

23. BRUSH MARKS

24. VARNISH
Definition:
●A transparent solution of
resinous substance in linseed
oil, turpentine or in alcohol is
called varnish.

25. VARNISH

26. Characteristics of a good
varnish
●It should dryrapidly.
●Itshould form a hard film on drying.
●It should not crack ondrying.
●Itshould bedurableand weatherresistant.
●It should give uniform andpleasing
appearance.
●It should not hide the natural grainsof the
inner surface of timber.

27. Painting the woodwork - Steps
1. Preparation of surface:
The new wood should be seasoned andit
must be dried before painting. The
surface of the wood should be cleaned
and nails should be punched below the
surface.
2. Knotting:
The knots covered with suitablematerial
is called knotting.

28. 3. Firstcoat:
After knotting the primary coat is applied on
the surface of the wood. It is usually applied
before the wood work isfixed.
4. Second coat:
This coat is applied after knotting and priming
coat. Each coat applied longitudinally in thin
film and crossed, so that no brush mark is seen
on this paintedsurface.
5. Final coat:
This coat is applied overthe second coat
without any brush mark.

29. Surface Preparation for
Enamel painting
 Previously painted wooden surfaces must be
properly sanded to remove any dustorgrease.
 Applywood primer by brush, after thinning to
given ratio by recommendedthinner.
 Allow it todry for 6-8 hr then apply puttyor
Lambi
 Sand the applied putty with number 180 sand
paperand then apply second coatof wood primer.
 Now thewooden surface is ready forpainting
with the topcoat

30. Painting with enamel
Apply wood primer by brush, after
thinning to given ratio byrecommended
thinner.
Allow it todry for 6-8 hr then apply putty
or Lambi.
Sand the applied putty with 180 no. sand
paperand apply 2nd coatof wood primer.
Now thewooden surface is ready for
painting with the topcoat

31. Enamels are normally applied bybrushing
although they can also besprayed.
The drying time of enamels is longer;hence
care must be taken to ensure a dust free
environmentwhile the paint film is drying.
Twocoats of paint is sufficient in most
cases, however if theearlierpaint shadewas
significantly darker than the new shade an
additional coat of paint isrecommended.

32. THANK YOU