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AR 236 BUILDING TECH. 1 LECTURE SERIES FINALS CEBU INSTITUTE OF TECHNOLOGY-UNIVERSITY ARCHITECTURE DEPARTMENT PAINTS and PAINTS and COATINGS COATINGS COMPONENTS OF PAINTS COMPONENTS OF PAINTS Paints consist of a blend of components, each with their specific function. Commonly these include the binder (or medium), solvent , base , extenders , pigments and driers , although other additives may be incorporated into specialist paints. The binder solidifies to produce the paint film. Traditionally, the binder was natural linseed oil, which set by gradual oxidation on exposure to air. However, linseed oil has now largely been replaced by alkyd resins which oxidise in air, or vinyl and acrylic resins which solidify by drying. To ensure adequate fluidity of the paint during application by brushing or spraying, either water or organic solvents (hydrocarbons, ketones or esters) are incorporated; paint thinners have the same effect. The base material, usually white titanium dioxide, produces the required opacity, although the body of the paint may be increased by the incorporation of inert extenders such as silica, calcium carbonate, china clay or barytes. Colouring materials are frequently a mixture of organic and inorganic dyes and pigments. Driers which induce the polymerisation of the binder ensure a rapid drying process.
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Page 1: paints and coatings

AR 236 BUILDING TECH. 1 LECTURE SERIES FINALSCEBU INSTITUTE OF TECHNOLOGY-UNIVERSITY

ARCHITECTURE DEPARTMENT

PAINTS and PAINTS and COATINGSCOATINGS

COMPONENTS OF PAINTSCOMPONENTS OF PAINTS

Paints consist of a blend of components, each with their specific function. Commonly these include the binder (or medium), solvent, base, extenders, pigments and driers, although other additives may be incorporated into specialist paints.

The binder solidifies to produce the paint film. Traditionally, the binder was natural linseed oil, which set by gradual oxidation on exposure to air. However, linseed oil has now largely been replaced by alkyd resins which oxidise in air, or vinyl and acrylic resins which solidify by drying. To ensure adequate fluidity of the paint during application by brushing or spraying, either water or organic solvents (hydrocarbons, ketones or esters) are incorporated; paint thinners have the same effect. The base material, usually white titanium dioxide, produces the required opacity, although the body of the paint may be increased by the incorporation of inert extenders such as silica, calcium carbonate, china clay or barytes. Colouring materials are frequently a mixture of organic and inorganic dyes and pigments. Driers which induce the polymerisation of the binder ensure a rapid drying process.

Page 2: paints and coatings

AR 236 BUILDING TECH. 1 LECTURE SERIES FINALSCEBU INSTITUTE OF TECHNOLOGY-UNIVERSITY

ARCHITECTURE DEPARTMENT

Environmental concerns have led to the development of paints with reduced levels of volatile organic compounds (VOCs). Mainly this has been through the increased use of water-borne rather than solvent-borne paints.

Page 3: paints and coatings

In some respects water-borne paints have the advantage. they have low odour emissions, brushes can be cleaned in water, and they will tolerate damp surfaces. however, they are not ideal for use externally in cold and wet conditions. Other developments have been towards high solids paints, which have low solvent content and therefore very low voc emissions.a further trend is towards the use of natural paints based on plant and mineral compositions, which incorporate a lower proportion of components of high embodied energy materials such as titanium dioxide and petrochemical products these new formulations consume considerably less energy in manufacture, are environmentally friendly in application and less problematic in waste management; however, they are not suitable for all applications.

Page 4: paints and coatings

AR 236 BUILDING TECH. 1 LECTURE SERIES FINALSCEBU INSTITUTE OF TECHNOLOGY-UNIVERSITY

ARCHITECTURE DEPARTMENT

PAINT SYSTEMS

Coats within a paint system perform specific tasks. usually a complete system would require primer, undercoat and finishing coat, although in the case of new external materials, four coats may be appropriate.

Page 5: paints and coatings

AR 236 BUILDING TECH. 1 LECTURE SERIES FINALSCEBU INSTITUTE OF TECHNOLOGY-UNIVERSITY

ARCHITECTURE DEPARTMENT

PRIMERS

The primer must adhere well to the substrate,offer protection from deterioration or corrosion and provide a good base for the undercoat. To ensure adhesion, the substrate surface must be free of loose or degraded material. For use on timber, primers may be oils, alkyd resins or acrylic emulsions, frequently with titanium oxide. Aluminum wood primer is recommended for resinous woods and to seal aged creosoted and bitumen-coated surfaces. For the corrosion protection of ferrous metals, primers incorporate zinc or lead-rich compounds within oils or alkyd resins. While lead-based paints such as red lead and calcium plumbate are considered environmentally less acceptable than the alternatives, they remain very efficient in the inhibition of steel corrosion.

Page 6: paints and coatings

AR 236 BUILDING TECH. 1 LECTURE SERIES FINALSCEBU INSTITUTE OF TECHNOLOGY-UNIVERSITY

ARCHITECTURE DEPARTMENT

PRIMERS

The newly developed low-VOC coatings offer temporary protection against the corrosion of structural steelwork either as prefabrication or post-fabrication primers. Alternatively, acrylated rubber paints, which form a physical barrier over steel, may be used as primers. For non-ferrous metals, zinc phosphate primers are frequently used. The application of primers suitable to ferrous metals may cause increased corrosion on non-ferrous substrates, particularly aluminum Masonry paints are usually based on alkyd or acrylic resins with titanium oxide; where surfaces are likely to be alkaline, such as new plaster, brickwork or concrete, alkali-resisting primer should be used.

Page 7: paints and coatings

AR 236 BUILDING TECH. 1 LECTURE SERIES FINALSCEBU INSTITUTE OF TECHNOLOGY-UNIVERSITY

ARCHITECTURE DEPARTMENT

UNDERCOATS

Undercoats provide cover and a good base for the finishing coat. Most undercoats are based on alkyd resins or acrylic emulsions.

Page 8: paints and coatings

AR 236 BUILDING TECH. 1 LECTURE SERIES FINALSCEBU INSTITUTE OF TECHNOLOGY-UNIVERSITY

ARCHITECTURE DEPARTMENT

FINISHING COATS

Finishing coats provide a durable and decorative surface. Some gloss, eggshell and satin finishes are still based on oils and alkyd resins, although increasingly water-borne products are becoming predominant. Some water-borne gloss finishes tend to be visually softer and are more moisture-permeable than the traditional solvent-borne hard glosses. However, they have the advantage of quick drying without the evolution of solvent odor; generally they are more durable and do not yellow on ageing. Matt and silk finishes are usually vinyl or acrylic emulsions.

Page 9: paints and coatings

AR 236 BUILDING TECH. 1 LECTURE SERIES FINALSCEBU INSTITUTE OF TECHNOLOGY-UNIVERSITY

ARCHITECTURE DEPARTMENT

SPECIAL PAINTS

Multicolor paints incorporating flecks which give a hard wearing surface.

Broken colour paints effects, reflecting the traditional processes of graining, marbling, ragging and stippling.

Acrylated rubber paints are suitable for internal and external applications exposed to chemical attack or wet and humid atmospheric conditions.

Heat-resisting paints. Aluminium paint, which has a lustrous metallic finish, is resistant to temperatures up to 230–60°C.

Micaceous iron oxide paints have good resistance to moisture on structural steelwork, iron railings, etc., due to the mica plates which reduce permeability to moisture vapour.

Page 10: paints and coatings

AR 236 BUILDING TECH. 1 LECTURE SERIES FINALSCEBU INSTITUTE OF TECHNOLOGY-UNIVERSITY

ARCHITECTURE DEPARTMENT

SPECIAL PAINTS

Masonry Paints. Smooth- and sand-textured masonry paints are suitable for application to exterior walls of brick, block, concrete, stone or renderings.

Fungicide paints for application in areas where mould growth is a recurrent problem usually contain a blend of fungicides to give high initial activity and steady long-term performance.

Page 11: paints and coatings

AR 236 BUILDING TECH. 1 LECTURE SERIES FINALSCEBU INSTITUTE OF TECHNOLOGY-UNIVERSITY

ARCHITECTURE DEPARTMENT

WATER-REPELLENT AND WATERPROOFING PAINTS

Silicone water-repellent paints can be applied to porous surfaces including brick, concrete, stone and renderings to prevent damp penetration.

Epoxy waterproofing systems may be applied to sound masonry surfaces to provide an impervious coating. Typical applications are to rooms where condensation causes the blistering of normal paint films; also in basements and solid external walls where penetrating water is a problem.

Bituminous paints provide a waterproof finish to metals and masonry and may be used as a top dressing to asphalt or for renovating bitumen sheet roofing.

Page 12: paints and coatings

AR 236 BUILDING TECH. 1 LECTURE SERIES FINALSCEBU INSTITUTE OF TECHNOLOGY-UNIVERSITY

ARCHITECTURE DEPARTMENT

EPOXY PAINTS

Epoxy ester paint coatings are highly resistant to abrasion and spillages of oils, detergents or dilute aqueous chemicals. They are therefore frequently used as finishes to concrete, stone, metal or wood in heavily trafficked workshops and factories. Many are produced as two-pack systems requiring mixing immediately before application.

Page 13: paints and coatings

AR 236 BUILDING TECH. 1 LECTURE SERIES FINALSCEBU INSTITUTE OF TECHNOLOGY-UNIVERSITY

ARCHITECTURE DEPARTMENT

NATURAL WOOD FINISHESNatural wood finishes include wood stains, varnishes and oils.

Wood stains are pigmented resin solutions which penetrate into the surface and may then build up a sheen finish. Varnishes are unpigmented resin solutions which are intended to create a surface film.

WOOD STAINS. Most wood stain systems for exterior use include a water- or solvent-based preservative basecoat which controls rot and mould growth.

VARNISHES. Traditional varnishes are combinations of resins and drying oils, but most products are now based on modified alkyd resins. Polyurethane varnishes areavailable in matt, satin or gloss finishes, based on either water or solvent-based systems.

OILS. Oils such as teak oil are used mainly for internal applications. Formulations based on natural oils for exterior use are high in solids producing an ultraviolet resistant, microporous finish which may be transparent or opaque.

Page 14: paints and coatings

AR 236 BUILDING TECH. 1 LECTURE SERIES FINALSCEBU INSTITUTE OF TECHNOLOGY-UNIVERSITY

ARCHITECTURE DEPARTMENT

REFERENCESLyons, Arthur (Arthur R.), 2007. Materials for architects and builders. - 3rd ed.. Hoboken,

Linacre House, Jordan Hill, Oxford OX2 8DP, UK: Elsevier