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An Overview of Paints and Coatings

L N Ranganath, Executive Director, M/s Hallmark

"Paints and Coatings" are a very significant and relevant industry today, globally. With the bench mark for ‘Appeal and Performance’ of a finished product raising by the day, the necessity to Design and Innovate products and finishes to satisfy this want is growing manifolds. Scientist, chemical engineers, paint technologist and manufacturers are engaged in development of processes and strategies to formulate and manufacture such performance oriented products that are world class and minimize the effect of environmental pollution. The world as such is looking forward for Greener products and services. The article to follow gives a brief overview of the 'Paints and Coatings industry' as relevant today.

Definition

Paint as a product, can be defined in many ways. In the present context, this article considers defining 'Paint' in three following most widely accepted ways;

• A product that brings smiles on one's space and responsible for mood swings by its shear presence and depictions in a broad sense could be termed as "Paint".
• Technically speaking Paint can be defined as a solution of pigment in water/oil or an organic solvent used to cover a wide variety of substrates for protection and aesthetics.
• Alternatively, it could be termed as a liquid or a mastic composition upon application to a substrate in a thin layer converts to a solid film upon drying there by imparting colour or texture to an object.

History

The practice of painting dates back to prehistoric times. Paints were prepared from natural minerals and applied to their caves and living structures. It was a medium of communication and language depiction. Initially carbon and metal oxides were used as pigments which were mixed with blood, milk and plant extrudates as binders. Egyptian advanced further and developed blue, red, black and yellow colours from roots of plants and casein as binder.

Paint formulation was an art and later in the 19^th century it started to evolve as a technology. Though the first varnish plant appeared in US in the year 1815, regular paint production was started in the year 1914. In India Shalimar paints first started the paint industry in Calcutta in the year 1902.

Recent Trends

The paint industry today is very robust incorporating the latest State of Art technology for manufacture derived from different chemistries, offering mind boggling products which are not only environment friendly but add great value to the products painted with excellent aesthetics and unparalleled protection.

With increased awareness and concerns for environment along with health issues, paint manufacturers today all over the world are adopting manufacturing processes that has almost eliminated the use of certain harmful constituents used in paints like heavy metals namely Lead, Mercury and Cadmium, along with replacement of products for Volatile Organic Compounds (VOC).  The paints manufactured today are stamped with GSII (Green Seal) Standard for Global health and environment safety standards.

The Green Seal Standard is a non-profit organization that defines a worldwide standard meant for paint and coating industry to follow. The guiding principles are to reduce such materials which are hazardous to environment, health during manufacture, product life cycle and service.

Market size

Globally the market value for paints and coating industry is estimated to be 127.3 billion USD (approx. about 7.6 Lakh Crores in INR) for the FY 2013.

Increased demand for paints and coatings is mainly due to the continued recovery of the global economy and rapid industrialization, and depends largely on the end-user industries it serves, such as steel, automobiles, and furniture and construction industries. In addition, increasingly stringent system of competition, as well as a unique formulation technology and product development will continue to stimulate growth in the global market.

From the end-user sectors, architectural coatings business is still dominated by the overall market, next is protection of the marine and general industrial coatings. Architectural coatings accounted for about 40% of industry revenue, product polish (for cars, furniture, etc.) accounted for 25% and 20% of industrial coatings.

From geographical side, 2013 was the most rapidly growing developing emerging markets, especially the Asia-Pacific region, accounting for 48% of the world. Asia Pacific Coatings market is mainly to promote economic growth markets including China, India and Indonesia. European representatives of the world's second largest regional market paint, next is North America and Latin America.

Top Brands

Global Players

Some of the top brands in the world as per 2013 ratings are:

• AKZONOBEL (N.L.)
• PPG Industries (U.S.)
• SHERWIN-WILLIAMS (U.S.)
• DUPONT (U.S.)
• BASF (D.E.)
• VALSPAR (U.S.)
• DIAMOND Paint (U.S.)
• SACAL (U.K.)
• NIPPON Paint (J.P.)
• RPM Inc (U.S.)

Indian Paint Industry

There are 10 big players in the Indian paints and coating industries and about 2500 medium and small scale paint manufacturers contributing to the growth and wellbeing of the industry.

The paint industry in India is growing at the rate of 12 to 13 % per annum and currently valued at about 13500 crores and said to cross 1 lakh crore by 2025 with the increase in the consumption of paint which is merely about 1.5 kgs/capita/person as against 20 kgs/capita/person in Europe and 5 kgs/capita/person in other Asian Countries. Average age of an Indian taken to be around 29 yrs, the industry estimates such a growth and is the main reason for many multinational paint companies to enter Indian paint operations.

Some of the Top Paint Companies in India are:

• Asian Paints
• Kansai-Nerolac Paints
• Lewis Berger paints
• Azko Nobel Paints (ICI Paints)
• Shalimar Paints

Classification

In depth study of Coatings helps us to classify the Paints based on many parameters including application, utility, and degree of emission of VOC etc. Some of the important classifications are discussed as under;

Based on Application-

• Architectural Coatings- Paints used for decorative coatings in building industry.
• Industrial Coatings- Paints that are used by OEM’s for finishing as in the case of automobile sectors and other industrial product finish applications.
• Speciality Coatings- Paints that are used for Special Applications viz. Thermal insulation, Heat resistant Paints etc.

Based on Chemical Backbone Resin

• Epoxy Paints- used for machinery paintings, Industrial Shop floors etc.
• Poly Urethane Paints- used in automobile sector, building sector etc.
• Acrylic paints- generally used in building sector
• Alkyd Paint- General Purpose synthetic Enamels widely used in industrial and building segments.
• Polyester Paint- Used to coat aluminium section and other metal section.
• Rubber Paints- Swimming Pools and Shipping Industry.
• Silicone Paints- Water repellent paints for building decorative industry.

Based on Degree of Emission of VOC

• Powder Paint- Powder Coating
• Water Based Paint- Acrylic Emulsions
• Paint with High Solid Content- Acrylic Emulsions
• Solvent Based Paints- Enamels, Epoxies, Polyurethane, etc.

Based on number of components needed to dry or cure the paint

• Single component paint-  Enamel, Emulsion Paint
• 2 Component Paint- Comprising of a base Paint and a Hardener to achieve curing of paint  (Epoxy and Polyurethane Paint)

Based on Number of Coats

• Direct Paint-Directly applied on the substrate.
• Mono layer Paint-Primer followed by Enamel/Emulsion Paint.
• Bi layer Paint-3 different layers consisting of Primer, Base coat followed by varnish/lacquer.
• Tri layer Paint- 4 different layers consisting of primer and subsequent three finishing coats. This system is employed in automobile sector.

Specialty Paints

 

Fire Retardant Paints and Coatings

Special purpose paints are used where permanence is the primary criteria-

• Fire Retardant Paints- Paints that are used for in building sector (fire escape doors) in fire escape staircases, on motors and machineries used in manufactures of solvents that are highly inflammable.
• Heat Resistant Paint- Paints that are applied on the top surface of roofs of the buildings to bring down the surface temperature and lower the heat transfer in the inner surface of the roof slab.
• Thermal Insulation Paint- Used in industrial Boilers, Geysers and as coatings for under deck and over deck roof slabs of buildings.
• Rust Converters- Paints that combine with existing rust on the metal surface and then converting them into protective film on the surface of metals.
• Anti Rust Coatings- Paints that are used in highly humid and saline environmental conditions on metal surface to protect against rusting
• Chemical Resisting Paint- Paint that is used in industries engaged in manufacture of acidic and alkaline substances which affects the machineries and floors etc.
• Anti Carbonation Paint- Paints that are used for constituents of infrastructure projects like the deck slab supporting columns and beams.
• Texture Coatings- Coatings that are used both for building exteriors and interiors for the purpose of building decorations and protection.
• Water Proof Coatings- Coatings that are used to prevent water ingress into the structure like the roof tops, sunken slabs and retaining walls.
• Antibacterial and Microbial Paint- Used in clean room applications, hospitals and pharma industries.

• Marine Paints- Also known as Anti Fouling Paints which is used to protect the hulls of boats from fouling by marine organisms.
• Radar Radiation Absorbent Paint- Used in high end stealth jet bomber aircrafts to avoid detection from enemies’ radar.

 

Anti Microbial Paint

Paint Components

Paint is mainly made up of 4 categories of materials:

• Binders
• Pigments
• Extenders
• Solvent and Additives

The paint material in the liquid form is a colloidal dispersion of pigments and additives in a polymeric binder medium dissolved or dispersed in a solvent combination. This viscous thixotropic material contains volatile and non volatile parts. The volatile parts contain volatile organic solvents where as the non volatile parts contains binder, pigment extenders and additives. When the liquid paint is applied over the substrate the volatile part evaporates leaving behind a solid dried cured organic coating over the substrate.

• Binder or Resin- This is a viscous polymeric material which forms the heart of the coatings. It binds together the other component. It is also known as film former or vehicle.
• Solvent- This dissolves the polymer and facilitates easy application. The polymer and the solvent form the continuous phase of the paint. On application the solvent evaporates leaving the cured film containing binder, pigment and additives.
• Pigment- It is finely ground powder of various shades. It provides opacity, colour durability and strength to the film.
• Additives- These are performance enhancing constituents which are added in small quantities to improve the properties and performance of paints.

VOC - Implications

• VOC-Volatile Organic Compounds are gases that are emitted by solids or liquids that are used in paint. On application to a substrate these evaporate during the drying process. Solvents in traditional paints often contain high quantities of volatile organic compounds.
• VOC impacts the air quality in different ways, primarily as an irritant or as a contributor to Green House Gas emission. VOC reacts with oxygen in presence of sunlight to form Ozone (O₃) which is termed as 'Bad Ozone' which occurs at ground level. The 'Bad Ozone' can also damage vegetation-plant, Tree and bushes. This ‘Bad Ozone’ causes nose, eye and throat irritation and can lead to shortness of breath. This is especially harmful to asthmatic patients and people who are allergic to chemical smell/odour.
• A further major consequence of VOC emission is ‘Global Warming’, which is a result of Green house effect.

Low VOC / Green Paints

For a paint to be termed low VOC paint, the paint should contain < 50gms/ltr of VOC.

Zero VOC Paint Mark

To qualify the Green Paint or zero VOC paint should be < 5gms/ltr of VOC.

Low VOC includes water based acrylic paints.

Most recent estimates suggests roughly 10% of total VOCs come directly from paint and coating industry of which architectural coatings contribute 4% while industrial coatings 6%.

In the USA, items containing toxic ingredient have registration numbers issued from any one of the following;

• US Environmental Protection Agency
• Occupational Safety and Health Administration
• United States Department of Transport

Painting Vs Coating

It is sometimes difficult to differentiate between the terms ‘Paint’ and ‘Coatings’.

Coating is more generic term and encompasses paint. While Paint is applied on the substrate to impart colour, for example- Internal wall, Coating is a covering applied to improve the surface condition and to protect the substrate, example-Water Proof coating.

Texture Paints

 

Smooth Textured Finish

Texture paints throughout the world have taken people by surprise for its sheer aesthetics and protection value. Texture paint now has become a standard product for coating the external surface of high raised buildings in India and abroad.

Texture paints or specialty paints that are applied to the external and internal wall surface of the buildings to enhance the aesthetic value and to also protect the surface textured against adverse climatic conditions. These materials on application and drying offer an elevated surface thereby creating an uneven pattern surface which looks and feels good. Texture paints may be classified into two segments based on the nature of surface finish they exhibit. External Texture Finishes can be used in a limited way on the internal wall surface of the building but interiors smooth finishes are not recommended for exterior applications. Table

• Rough or rugged finish- These finishes comprise of Scratch finishes, Bubbles spray finishes, Roller finishes, Natural/Artificial coloured stone finishes, Granular finish and flaky finishes.
• Smooth finish- These finish comprises of multi-colour spay finishes, spatula finish, roller finishes etc.

 

Difference between texture paint and conventional Paint is discussed in Table 1

Table 1: Texture Paint Vs Conventional Paint

Sl. No.	Properties	Conventional Paint	Texture Paint
1.	Viscosity	Viscous but has to be thinned down either by water or a solvent for application on substrate.	Very viscous and need not be thinned down for application but instead apply directly on the substrate with only a trace of thinning if required.
2.	Dry-Film Thickness	Generally the film Thickness varies from 45 to 60 microns upon drying.	Thickness varies from 1mm to 2.5mm depending upon the texture used.
3.	Surface undulation	Exhibits surface undulation upon application to substrate if substrate already possesses one.	Camouflages the surface undulations in plasters to reasonable extent.
4.	Surface preparation	Good surface preparation is needed before final top coat application so as to achieve a neat, clean and uniform surface.	Thorough surface preparation is not needed to achieve required level of finish except in smooth texture finish.
5.	Resistance to abrasion	Abrasion resistance is satisfactory and if too much pressure is applied there is a possibility of paint peeling.	Offers excellent Abrasion resistance.
6.	Resistance to Moisture Ingress	Reasonable level of resistance is offered by exterior emulsion but interior emulsions are generally bad.	Offers excellent resistance to moisture ingress there by acting as protective coat.
7.	Visual effect	Offers neat and uniform finish.	Offers excellent visual effect specially multi coloured paint finishes, granite finishes are a treat to watch.
8.	Value Addition	Newly painted surface offers some value addition.	Great value addition both from aesthetics point of view and protection front.
9.	Skilled Labour	Semi skilled person is required.	Special skills or training required to achieve the desired results.
10.	Economy	Economical	Expensive

Texture Application Areas

Rough Texture

Rough/Rugged Texture (Spray, Scratch, Roller Finish, Stone finishes and Flaky finishes)-These textures are recommended in such areas where physical contact with the wall is minimal as the surface finish is rough in nature. These textures offer excellent protection to walls coated with, against adverse climatic conditions namely sun, rain and humidity.

• External walls of building specially high raised structures
• Side walls of staircases
• Wall behind the reception counter
• Corridor and passages of the buildings
• Headrest walls in bedrooms
• Showroom as backdrop for product displays

Smooth Texture

Smooth Texture Finishes can be used in a limited way on the internal wall surface of the building but interiors smooth finishes cannot be used on External walls. Typical areas for Smooth Texture Application (Spray, Multi coloured finishes, Roller finish and Spatula finish) are:

• One wall of leaving room or bedroom
• Side walls of staircases, lobbies and corridors
• Backdrop wall of reception at offices
• Internal walls of offices, Show rooms and commercial spaces (soft variety)
• On false ceiling to break the monotony and to add texture to the ceiling

 

Note: The colours of texture can be infinite so are the combination and their areas of application based on one’s imagination.

Significance of Texture Finishes

There is a wide spread notion that texture finishes are applied on to the external wall surface of the building for decoration/aesthetic purposes, seldom realizing the intrinsic  protection value the product has got to offer. Scratch finish textures are formulated and manufactured on two platforms.

• White cement based texture finish
• Acrylic based texture finish

White cement based texture finish

These texture finishes are sold in powder form and available in 30 kg polythene sacks. The powder is then mixed with water in a vessel and stirred and makes it into a paste for application on the wall surface. These textures generally consist of marble powder, dolomite and other fillers along with white cement which acts as a binder for addition purposes. These textures can be applied on moist and damp surfaces except that there should be no running water. Being white cement based product the surface needs to be cured with water (though nobody does it) after the surface dries up. The manufactures may claim otherwise (No curing required).

Advantages of white cement based texture are:

• Textures can be applied on moist or damp surface without any issue.
• The product exhibits neat white surface finish with texture.
• Dry material can be stored for long periods but care to be taken that no moisture is present in the storage area.
• Very easy to handle and transport the material.
• Very economical.

Disadvantages of white cement based texture are:

• The product may not perform for the intended use which is protection.
• The product has no crack bridging properties as it is weak in tensile strength.
• The product is prone for moisture absorption being cement based.
• Being formulated on white cement plat form and marble powder also forming one of the major constituent the top coat paint fades out within a short period of time. Very evident in dark shades.
• Care to be taken during mixing of the material as it is corrosive (Rubber gloves must).

Acrylic based texture finish- Most of the drawbacks mentioned in the white cement based texture finish are taken care of by Acrylic based texture finish.

Do's and Don'ts

Interior Works

•  Always follow manufacturer's guide lines specifically with regards to dilution of paints.
• In case of powder putty (cement based putty), use primer after putty works and do not paint top coat directly.
• A stronger emulsion should not be applied over a weak paint (Emulsion should not be applied over distemper).
• Water based paint namely Acrylic distemper or Acrylic Emulsion should not be applied on chalk powder putty (as enamel, varnish are used in putty making) but instead oil bound distemper or enamel could be used.
• Ensure 5 to 6 hours of Top coat paint drying before taking up subsequent coats.
• Always use non shrink grouts for cracks and do not use POP or white cement (readymade crack filler are available in the market)
• Do not carry out painting work on damp or moist surfaces.

External Works

• External painting works should not be taken up if the walls are damp or wet
• External Painting should be avoided when the day temperature are above 45⁰ C but instead could be taken up in the early parts of the day or late evenings.
• Manufacture’s specification and dilution is very, very critical for external top coat and primers.
• Use of Lime wash (Cem and white cement as primer materials is a ‘STRICT NO’ .
• Use of good quality acrylic primers and especially in coastal area use of ‘Efflorescence Resistant Primer’ are a must for best and long lasting paints.
• Cracks on exteriors to be filled up with Acrylic based non shrink grout and use of white cement POP is counterproductive.
• In high humid and heavy rainfall area it is always recommended to use Elastomeric coatings or External acrylic texture coatings which would mitigate the effect of moisture on the structure.
• External painting work should not be carried out during Rainy season or the relative humidity is high as performance could be severely hindered.

Inference

Sobha, Hibiscus

The stake holders of the industry right from raw material suppliers, manufacturers, chemists, paint technologist and finally the end-users should strive for clean and Green technology so that the safety of the future generation is assured.

When seldom any compromise is made on the factor safety of structures, even if it means over-reinforcing the same, which is detrimental actually, the mindset of a few people to use inexpensive products and just paint the building and hand over to owner/association should stop. Even with some knowledgeable promoters and builders who charge their customers handsomely, the use of inferior paints for interiors (Distemper) under the guise that the customer will get the interiors done up and repaint it again speaks volumes.

Builders, developers, promoters, civil engineers and contractors should realize that no matter what, the superior value of materials used for construction its finally the quality of paints used, determines and showcases the project and the mind set. Paints add great intrinsic value to a building both tangibly and non-tangibly.  While a reasonably aged building which has used better quality paints retains and protects the structure there by offering good commercial value, a relatively new building with inferior paint loses its appeal and commercial value dented. It is therefore imperative; use of good ‘Paints and Coatings’ are a necessity and not a luxury.

About the Author:

L N Ranganath, an engineering graduate from Bangalore, is currently the Executive Director of M/s Hallmark Protective and Decorative Coatings Pvt. Ltd with its head quarters in Bangalore. Hallmark is engaged in manufacture of Specialty coatings and paints based on green platform. The organization is honoured to be a part of many developers, promoters, architects, engineers in around Karnataka, Kerala and Maharashtra. The Company is in existence and providing invaluable products and services to the industry for the last 22 years.