bld62003 mak paint

MAK/BLD62003/PAINT 1

What is paint?

Paint is more than just the color; it is a material that is applied as a liquid and dries by a variety of chemical processes to a solid state.

Purpose of paint:

1. Decoration

2. Protection

3. Identification

4. Sanitation MAK/BLD62003/PAINT 2

PAINT

(components)

Binder

Solvent

Base

Extender Pigment

Drier

Additives


BINDERS The binder exists to hold the pigment to the surface.

The binder is a polymeric substance, and is either dissolved in the paint or suspended in it by emulsifiers.

Harden to produce paint film

Natural linseed oil – set by oxidation on exposure to air

Bind pigments together

Gives adhesion to surface

Provide resistance to water, chemical & abrasion

Determines performance and resistance characteristics of a paint



• Natural oils that polymerize as they dry. • Take longer time to dry & have variable properties as the

balance of oils varies from crop to crop. Drying oils

• Most common resins to be used in solvent-based paints. • They are usually polyesters & used for both air-drying & heat-

cured paints. Alkyd resins

• These are emulsions in water and are the most common water-based binders for use in household paint.

Vinyl & acrylic emulsions

• These resins are based on polymers containing the simple

organic compound oxirane (ethylene oxide). • A variety of other components are added to give a wide

range of properties.

Epoxy resins

• Polyurethanes are polymers of any ester of carbamic acid,

H2N—CO2H. • Polyurethane-based paints are tough, durable films that

retain their gloss and are easy to clean. Often used for painting aircraft

Polyurethanes

SOLVENT: To act as a carrier for the pigments and resin

For emulsion paints the solvent is simply water, and for resin-based paints a variety of organic compounds are used with the most common being mineral turpentine.

Water or organic : hydrocarbons, ketones or esters

Same effect with thinner

Ease the application of paint

Evaporate completely once coating has been applied


BASE

Usually white titanium dioxide

Produces the required opacity/ solidity

EXTENDER

Increase the opacity

E.g silica, calcium carbonate


DRIER/ RESIN The binder to hold the pigment particles together

Provide adhesion to the surface painted

Induces polymerization of binder

Ensures a rapid drying process

Waterborne paints most often use acrylic emulsion polymers as binders.

Common acrylic polymer types are based on monomers such as methyl methacrylate and butyl methacrylate.

Traditionally, lower cost paints have been formulated on PVA (Poly Vinyl Acetate) binders.

Solvent-based resins come in a very wide range of types. The most common solvent-based resins are termed ‘alkyd resins’ that are normally used in enamel paints.

Urethane alkyds often used in clear varnishes. Protective coating resins include types such as Epoxy, Urethane, Polysiloxane and Moisture Cured Urethane.


PIGMENT To provide color & finish, hiding & control gloss

To protect the surface underneath from corrosion and weathering as well as helping to hold the paint together.

Both inorganic and organic substances are used, with the inorganic ones being in general cheaper but less clear colors.

Special pigments can be used to give metallic finishes (for car bodies), to be hard wearing (for road markings) etc.

Pigments are divided into two groups: 1. ‘Prime Pigments’ : Titanium Dioxide (white), Chrome Green Oxide, Yellow

and Red Iron Oxides, etc.

2. ‘Extender Pigments’ : Calcite (Calcium Carbonate), Talc (Magnesium Silicate), Mica, Barytes (Barium Sulphate), etc.


Additives

To enhance certain properties such as ease of brushing, mould resistant, scuff resistance, drying & sag resistance.

Low-odorless additives

Low solvent additives

Gives paint its smooth texture, driers, anti-settling agents, anti-skinning agents a& a host of others that enable paint to cover well & last long

Enhance performance


• Finely grounded minerals to provide extra volume to paint, reduce cost & make paint easier to be applied.

Extender

• Speed up dry process Drier, hardener,

catalyst

• Jelly like structure added to paint to provide a non drip paint & allow more paint to be held by brusher or roller

Gelling

• Improves stability of paint against organic growth e.g fungi or algae Fungicides


Water borne paint

• Soluble in water

• Applied in emulsion paint

• Less environment pollution, health & fire hazard

Solvent borne paint

• Soluble in liquid other than water

• Applied in enamel paint

• Provides glossy appearance

Acrylic base paint

• Water based

• Odorless

• Quick drying

• Durable & easy to use

Alkyd based paint

• Resin, oil modified

• Dry faster and harder than oil paint


PAINT (classes)

Primer

Undercoat

Sealer

Finishing coat


PRIMER

Substance that adheres well to substrate

Protects the material Offer a good base for the

undercoat Promotes adhesion Prevents absorption of

later coats by porous surfaces

Gives corrosion resistance over metal

UNDERCOAT

Ensures a good even color Provides good base for

finishing coat Provide a fresh surface of

uniform texture & color close to the finishing coat

Imparts opacity to the total paint system

Levels out minor irregularity


SEALER

Prevents migration of substances from substrate into later coats

FINISHING COAT

Durable and decorative surface

Determines visible gloss & texture of surface

Maybe resistance to chemical & weather


Most non-texture paint coatings are approximately 0.2mm – 0.4mm thick for coat (dry thickness)

Enough time must be allowed for drying each coat before applying the next coat

Prevent coats from mixing together

Excessively thick coats can result in sagging of paint or uneven drying


WALL

Painted with different non glossy colors

Doors and window frames sometimes are painted but can be either glossy or non-glossy

Purpose: aesthetic value & the quality of wall surface is maintain & last longer


CEILING

Usually non glossy

The designs are drawn according to different cultures

There are also ceiling paint in plain color


STEEL BARS

Bars made of steel are usually painted

To prevent steel from rusting easily

Paint used are usually glossy


PAINT

(types)

Multicolor

Broken color

Acrylated rubber

Heat resisting

Flame retardant

Intumescent coatings

Fungicide

Enamel

Micaceous iron oxide

Masonry

Waterproofing

Epoxy


MULTICOLOR

Incorporates flecks Gives a hardwearing

graffiti removal through spray gun

Can be adjusted to change pattern & texture of the fleck

Applied to dust & grease-free internal surface

BROKEN COLOR

Reflects traditional processes of graining, stippling.

Requires a base coat with clear colored glaze

Pattern the glaze to create desired effects e.g. metallic, shimmer, etc.

Odor free Dry within 2 hours


ACRYLATED RUBBER

For chemical exposure attach or wet & humid atmospheric conditions

Non environmentally damaging

Applied to metal or masonry by brushing or spraying

HEAT RESISTING

Aluminum paint Lustrous metallic finish Resistant to 230 – 260

degree Celsius The most satisfactorily is

100 degree Celsius


FLAME RETARDANT

Emit non-combustible gases when subject to fire

Consists of antimony oxide Applied to plywood and

particleboard E.g. matt, semi-gloss and

gloss Applied by brush, roller or

spray

INTUMESCENT COATINGS

Thin film 1mm – 2mm Fire protection to structural

steel without visual effect Expands up to 50 times to

form a layer of insulating form when exposed to fire

30, 60 or 120 minutes fore protection

Applied for timber


FUNGICIDE

For mould growth

ENAMEL

Highly durable Impact resistance Easily cleaned Hard floss surface For machinery & plant


MICACEOUS IRON OXIDE

Resistant to moisture on structural steelwork, iron railing

Mica plates reduces permeability to moisture vapor

Applied over metal primer

MASONRY

Smooth and sand texture Suitable for brick, block,

concrete, stone & rendering Hides fine cracks through sand

textured materials Contains fungicides to prevent

discoloration by moulds and algae

Water based Fast drying Forms a crystalline protective

layer over masonry


WATER REPELLENT & WATERPROOFING

Made of silicone Prevent damp penetration E.g. bituminous, epoxy etc

EPOXY

Highly resistant to abrasion and spillages of oils, detergents or dilute aqueous chemicals

Finishes top concrete, stone, metal & wood

Requires mixing immediately before applications


MASONRY WALL & CEMENT SUBSTRATES

Allow plaster to adequately dry

Apply 1 coat of alkali resistant sealer

1 undercoat 1 finishing coat

WOOD SUBSTRATES

Sanding, filling up gaps on fully seasoned wood

Apply 1 coat of aluminum wood primer

1 undercoat 1-2 finishing coat


Gives good protection to all kind of masonry surfaces from ultraviolet rays present in sunrays.

Good protection from severe climatic conditions i.e. rain, heat, water, humidity, salt atmosphere.

Prevents growth of fungus and bacteria on masonry surfaces.

Hides out irregularities, hair lining, roughness etc. thus giving smooth & pleasing appearance to all cemented masonry surfaces.


PROCESS:

Making the paste Dispersing the

pigment Thinning the paste Canning the paint


Dilution This usually occurs when the dilution of the paint is not done as per

manufacturers recommendation. There can be a case of over dilution and under dilution, as well as dilution with the incorrect diluent.

Contamination Foreign contaminants added without the manufacturers consent can cause

various film defects.

Peeling/Blistering Most commonly due to improper surface treatment before application

and inherent moisture/dampness being present in the substrate.


Chalking Chalking is the progressive powdering of the paint film on the painted

surface.

The primary reason for the problem is polymer degradation of the paint matrix due to exposure of UV radiation in sunshine and condensation from dew.

The degree of chalking varies as epoxies react quickly while acrylics and polyurethanes can remain unchanged for long periods.

Cracking Cracking of paint film is due to the unequal expansion or contraction of

paint coats.

It usually happens when the coats of the paint are not allowed to cure/dry completely before the next coat is applied.


http://en.wikipedia.org/wiki/Polymer_degradation



http://en.wikipedia.org/wiki/UV_radiation



http://en.wikipedia.org/wiki/Sunshine

Erosion

Erosion is very quick chalking. It occurs due to external agents like air, water etc.

Blistering

Blistering is due to improper surface exposure of paint to strong sunshine.


http://www.resene.co.nz/whatispaint.htm http://nzic.org.nz/ChemProcesses/polymers/1

0D.pdf Product variants: http://en.wikipedia.org/wiki/Paint


http://www.resene.co.nz/whatispaint.htm

http://nzic.org.nz/ChemProcesses/polymers/10D.pdf

http://nzic.org.nz/ChemProcesses/polymers/10D.pdf

http://en.wikipedia.org/wiki/Paint

Paint is used as decorative and protective films against a substrate. It is classified into four different groups. Discuss all of the FOUR (4) groups as follows: Water-borne paint Solvent-borne paint Acrylic base paint Alkyd based paint

(15marks) A coating that prematurely reaches the end of its useful life is said to have failed. Even protective coatings properly selected and applied on well-prepared surfaces gradually deteriorate and eventually fail. Describe the following failures of paint. Chalking. Cracking. Dilution. Blistering. Erosion.

(10 marks)


Paint is used as decorative and protective films against a substrate and made up of seven components. Name and discuss FIVE (5) of these components.

(15 marks) A coating is a covering that is applied to the surface of an object, usually referred to as the substrate. The purpose of applying the coating may be decorative, functional, or both. Differentiate the following types of coating: Primer Undercoat

(10 marks)


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