Description of paint manufacturing or formulation of paints, three main ingredients/constituents of paints, equipments used in making paints.

1. PAINTS
oPaints are fluid material that after applying over a
surface forms a solid, cohesive, decorative and
protective film.
oIt is primarily used for decorative purposes but also
as a protecting agent for the surface.
oIts use has been investigated in ancient Egypt where
artist would use paints for making paintings.
oPaint has three main ingredients
oPigment
oBinder
osolvent

2. Pigments (& Extenders)
o Pigments are solids which are responsible for giving color
to the paint system.
o Pigments are primarily opaque and provide opacity to
paints while Extenders are practically transparent and
does not impart color.
o Pigments – organic and inorganic.
o Most organics are manufactured, have brilliant color but
their opacity varies very much.
o Inorganic – natural and manufactured.
o Natural inorganics are oxides and hydroxides of Iron.
o Manufactured inorganics cover a wide range of colors
including whites.

3. Table Representing concentration of oxides of iron to obtain different colors

4. o Binders are the continuous phase in which pigments are
dispersed.
o It is responsible for the mechanical and protective
properties the paint has.
o Can be dissolved in solvents or suspended to form
emulsion.
o Provides adhesion to the surface
o Binders – organic and inorganic
o Organics include resins containing fatty acids, polymers.
o Inorganics include silica based materials like ethyl silicate,
alkali silicates and quaternary ammonium silicates.
o Convertible (thermoset binders) and non-convertible.
BINDER

5. o Solvents are used to render the pigment-binder system.
o It reduces the viscosity to ensure uniform coating
o After application, it is no longer required and should
vaporize quickly.
o Majority of solvents are toxic or are harmful, which is a
cause of concern.
o Solvents chosen are organic in nature.
o Plasticizers are taken in case of non-convertibles and are
mostly oils.
o Apart from these ingredients, additives might also be added to
impart or improve one or more properties.
SOLVENTS

6. POINTS TO KEEP IN MIND
o Interaction of solvent with other ingredients is
important.
o It should provide appropriate rheological properties
before and during application.
o Solvent release after application is an important
criteria
o If solvent remains in paint film after application, it
may cause internal tension and shrinkage.
o Selection of binder – based on compatibility with
solvents, type of drying etc.

7. Manufacturing of paints
o Starts with paste grinding process – where pigments
are broken down into fine particles.
o This is then introduced in mixer where binder and
solvents are added.
o It is then sent to another tank where further
materials are added to make it a finished product.
o Quality checking and testing follows after. Color
intensity, matching, viscosity, gloss etc. are being
tested.
o Paint is then filtered to remove any unwanted
particles before being packed.

8. PASTE MAKING
 It is an important part. Milling machines are preferred
for this.
 High-Speed Disperser (HSD) – Tank jacketed for
cooling, a motor & a shaft with blades bent at 900C.
 Dispersion is near or at the surface of blades.
 Operates at 915-1921.5 m min-1.
 Low maintenance, low labor, easy to operate.
 High power dissipation, needs easily dispersible
pigments.
 Latex, primers, plastisols, PU etc.

9. CONT…
 Continuous Milling Machine – based upon shearing action.
 Have high speed shafts with multiple discs.
 Have high rates, easy to clean and large batch sizes.
 Expensive to maintain, cannot grind tough pigments, requires
premix tanks.
 Primers, PU, lacquers etc.
 Ball Mill – In use from earlier times. Has a steel cylinder and
filled with 1/3 of it’s volume with steel balls which are
responsible for the grinding action.
 Up to 40% vol. should be of pigments, no solvent loss, low
maintenance, easy handling.
 Takes long time, discoloration from metal may occur,
becomes difficult to clean.
 Primers, alkyds, Polyesters, Acrylics, Lacquers.

10. DISPERSION/DISSOLVING
 Roller Mills – One to five rollers can be used with
three roll mill being preferable.
 First roller is slowest, second rotates at moderate
speed and third rotates fastest.
 Hopper is above first roller.
 Nip gap between first and second roller is small
which further shears the pigments. The other nip gap
ensures dispersion.
 Provides finish, removes dust and other unwanted
particles. Continuous process of pigment breaking
and dispersion.
 Very slow process; unsuitable if volatile solvents are
used.

12.  After paste-making, it’s dispersion into binder comes.
 Kneaders are first choice because of the variety it
can produce (highly viscous, putties, rubbery
composition).
 It can also be used for those systems which are
difficult to wet.
 Batch-wise or continuous operation.
 Pug Mixers are also used.
 Heavy-duty machines; provide high consistency.
 Horizontal and vertical arrangements
 Horizontal provides high consistency, while vertical is
used primarily for heavy pastes & putties.

13. Vertical Pug Mixer Horizontal Pug Mixer

14. FILTER SYSTEM
 Before filling, cleanliness must be ensured of the
end product.
 Sieves – Mesh or gauges made from steel (or
metals).
 Paints are poured onto a vibrating screen. It vibrates
either horizontally or vertically, allowing paint to pass
through sieves.
 Bag Filters – metal filter with closable and/or
sealable covers.
 Filter Cartridge – multiple cartridges are aligned on
after other through which paint passes. Synthetic
micro fibers are used as filter material (5-100 µm).

15. References
• Outlines of Paint Technology – W.M. Morgans
• Paints, Coatings and Solvents – D. Stoye & W. Freitag.
• Paint Technology Handbook – Rodger Talbert.
• Wikipedia
• Google (For pictures).