Paint is used to protect objects from adverse effects of weather e.g.
• A coat of paint protects buildings and structures from the effects of water and the sun by preventing water seepage and the effects of U.V. radiation which would otherwise make the building and the structures rot and degrade.
• Metal structures are painted to prevent them from rusting.
Paint is used to decorate all sorts of objects. Paint decoration is an important industry. Painted objects are more attractive and valuable.
Paintings are pictures done in paint. Paintings are usually done on board, canvas or paper. Old beautiful and famous paintings are very valuable.
Paint is used to give information by means of painted signs. This include road lane marking, street signs, warning signs, advertising signs to mention but a few
The color of an object is the color of the light leaving it’s surface and depends on the illumination and reflective properties of the surface.
Pigments are chemicals that selectively absorb and reflect different spectra of light. Light hitting a painted surface is reflected minus some wavelengths. Most paints are a blend of several pigments intended to produce a reflection of a certain color.
Color plays a vital role in the world we live in. It can sway thinking, change actions, cause reactions. It can irritate or soothe your eyes etc. When used in the right way colors can save on energy consumption. As a communication tool color is irreplaceable. Red means stop and green means go and traffic lights send this universal message.
This is the choice of colors used in design. Color schemes are used to create beauty and style. A basic color scheme will consist two colors that look appealing together. Most color schemes consist of various shades based around a single color such as different shades of blue from a light blue to a very dark blue.
Paint system components
A complete paint system should comprises of:
Primer is the preparatory coat before painting. Primers ensure adhesion and increases paint durability and provide additional protection to the substrate. They have good filling properties.
Wood is porous and absorbent. A coat of primer reduces porosity and ensures that the paint undergoes the proper drying cycle. A primer also reduces the paint requirement by filling and also ensures even color.
Water seepage to the bare metal results in corrosion through rusting. Metal primers contain anti corrosion pigments such as zinc that provide additional protection through sacrificial action.
This is a coat of paint applied before the top coat. Ideally it should be between the primer and the topcoat. Undercoat should be the same color or near same color as the topcoat. An undercoat provides the base for top coating and also fills minor cracks and imperfections.
This is the final and finishing coat that gives the desired characteristics of a paint system.
The quality of surface preparation, surface repair on new or previously painted surfaces greatly influence the performance and durability of any applied paint system. Since results of surface preparation and repair are quickly concealed by the first coat of paint, the effects are not usually evident until premature paint failure occurs.
The first step should be a thorough examination of the surface to be painted for peeling and faded paint, dirt, chalking, grease, cracking, knots, bare areas, mildew, rust, nail stains and structural problems. All surfaces, whether painted or unpainted, must be clean, free from shine, sound and dry prior to finishing.
Loosely Bound and Peeling Paint
Remove as much loose and peeling paint by scraping, wire brushing or power-washing the surface. Feather sand rough edges smooth until they blend with bare surface.
Dirt, Grease, Oil, Chalky Surfaces
Remove these deposits by washing with a detergent solution using a sponge or brush. Protected areas need special attention to remove invisible deposits that can promote a premature peeling problem. After washing, thoroughly rinse with clean water and allow it to dry. Power washing is also a fast, effective method of removing dirt, chalky deposits.
Spotty patches that look like dirt, but do not come off when scrubbed with detergent solution are probably mildew. Mildew can occur on any side of the house, but is more likely to grow in shaded areas or behind shrubbery. It can easily be identified from other forms of discoloration by applying a few drops of bleach. If mildew is present, the black, gray or brown color will bleach out and disappear within one or two minutes. Mildew must be killed and removed before repainting. If the mildew is not completely removed, the active spores will continue to grow and may almost immediately begin to reappear on a recently repainted surface. Where mildew is present, apply a solution of one-part household bleach and three parts water.
Remove all rust by sandblasting, wire brush, steel wool or sandpaper. See Iron, Steel and Ferrous Metal section for SSPC preparation methods.
Cracks, Splits and Open Joints
Cracks and/or open joints, where water may enter should be sealed with a high-quality paint-able sealer. Apply primer over sealed area.
Always rub down surfaces with sandpaper.
Replace loose nails with slightly larger, galvanized nails. Leave nail heads flush with hardboard surfaces and counter sink on all other wood surfaces. Prime with a corrosion resistant primer.
This condition can be encountered on hardboard surfaces. If a stain or discoloration persists after removing dirt and/or mildew, it may be a wax migration from the siding. It can be identified by applying a few drops of water, both to a discolored area and an adjacent non-discolored area. If the water beads on the discolored area, but spreads or is absorbed in the areas around the stain, a wax migration condition probably exists in the stained area. In most cases this discoloration can be removed with a hot detergent solution, followed with a thorough rinsing with clean water. In extreme cases removing the stain by wiping the area with a clean rag, wet with mineral spirits, may be necessary, followed by a detergent solution wash and clean-water rinse. Repeating either process may be necessary until clear water ceases to bead up on the affected area. Prime the affected area prior to top coating.
Previously Coated Surfaces
It is not always possible to remove all old coating for repainting works. Understand that any surface preparation, short of complete removal of all old coatings, may compromise the service life of the new coating system. Check compatibility of previously painted surfaces using a test patch with the coating if there is any doubt on re coat-ability.
New Aluminum and Galvanized Surfaces
To paint these surfaces, you must start by solvent cleaning (with mineral spirits) to remove any oily residue. Prime with either a good quality latex or oil primer formulated for these surfaces.
All that is necessary is to wipe it clean from dirt and prime with oil or latex primer.
Shall be cleaned free of dirt, oxides and foreign matter. Acid etching may be required to remove oxidation. Prime with an oil-based product.
Brass and Bronze
Remove only loose tarnish, but not all tarnish needs to be removed. Then wash with detergent to get rid of dirt and grease. Rinse well and allow to dry. Prime with a top-quality oil metal primer.
Start by roughing up the surface with fine sandpaper or emery cloth. Wash with soap and water, then rinse and allow to dry. Prime with oil-based metal primer.
Iron, Steel and Ferrous Metal
Wipe clean with mineral spirits to eliminate any oil or grease. Remove all rust and mill scale. Prime with a good oil-based metal primer.
Iron and Steel: If the old film is in good sound condition, all that needs to be done is to de-gloss the old surface with light sanding and clean with mineral spirits. If the old film is in poor condition, it should be removed with paint remover. Remove all rust and prime all bare spots with oil-based metal primer.
White Metal Blast Cleaning
A surface with a gray-white, uniform metallic color, slightly roughened to form a suitable anchor pattern for coatings. This surface is free of all oil, grease, dirt, mill scale, rust, corrosion products, oxides, paint and other foreign matter.
Near White Blast Cleaning
A surface from which all oil, grease, dirt, mill scale, rust corrosion products, oxides, paint or other foreign matter have been removed except for light shadows, streaks or other discolorations (of oxide bonded to metal). At least 95% of any given square inch has the appearance of “White Metal” and the remainder is limited to slight discolorations.
Commercial Blast Cleaning
A surface from which all oil, grease, dirt, rust scale and foreign matter have been removed except for slight shadows, streaks or discoloration caused by rust stain or mill scale oxide binder. At least two-third of any square inch shall be free of all visible residues and the remainder shall be limited to light discoloration, slight staining, or light residues mentioned above. If the surface is pitted, slight residues of rust or paint are found in the bottoms of the pits.
Brush-Off Blast Cleaning
A surface from which oil, grease, dirt, loose rust scale, loose mill scale and loose paint are removed, but tightly adhering mill scale, rust, paint and coatings are permitted to remain if they have been exposed to the abrasive blast pattern, so that numerous flecks of the underlying metal are uniformly distributed over the entire surface.
Removal of oil, grease, dirt, loose rust, loose mill scale and loose paint by water at pressures of 2000-5000 psi.
Wash to remove grease with a detergent solution. Sand lightly to etch the surface. Prime with epoxy metal primer.
New or Unpainted Concrete Floors
Floors – Check for any dampness on floors by placing a rubber mat down and leaving overnight. If water accumulates on the back side of the mat or concrete surface has been darkened by moisture – Do Not Paint. New concrete should be allowed to cure 30 days before to painting.
Painted Concrete or Wood Flooring
Be sure surface is free from dirt, dust etc. by sweeping or vacuum cleaning. Remove grease, oil, floor compound and wax by chemical cleaning. Scrape carefully to remove deteriorated coatings. If remaining coating is glossy or very hard, sand it lightly for good adhesion of subsequent coatings. The surface must be thoroughly dry before coating.
Masonry Block and Concrete
Allow to dry 30 days under normal drying conditions prior to painting. If efflorescence or cement dust is present on masonry and concrete, it should be removed completely. Flush off surface with clean water and allow to dry. Surfaces should also be free of all dust, dirt and loose or excess mortar. Porous surfaces should be filled with emulsion sealer before painting.
Unpainted Stucco and Brick
This needs no special preparation. However, stucco should be allowed to sit and dry thoroughly before it is painted. If surface is soft or slightly powdery, first apply one coat of penetrating primer. Apply two coats of emulsion primer formulated for masonry.
Should be cleaned and free from loose paint and all holes should be patched. Paint with exterior latex.
Ceramic Tile and Glazed Brick
Wash with detergent, then roughen surface. Paint with a good quality 2-part epoxy paint.
Unpainted Exterior Wood Surfaces
Should be clean and dry. Prime and paint as soon as possible. No painting should be done immediately after a rain or during foggy weather. All nail holes or small openings should be filled after the primer application.
Before finish is applied to the panels, they must be cleaned. Apply an alkyd or latex primer, even if hardboard is pre-primed, then finish with desired topcoat.
If glazed, allow at least two years before painting. If shingles are porous, treat with penetrating primer. If shingles are weathered, remove all dirt and dust. Apply a coat of emulsion primer.
Plastered surfaces should be allowed to dry for at least 30 days before painting. Bare plaster should be dry, cured and hard. Fill any holes and cracks. Surfaces previously applied with a cement-based coating or lime wash should be first be treated with a penetrating primer.
Woodwork – Interior
All finishing lumber and flooring should be sanded smooth, with the grain not across it. Surface blemishes should be corrected.
Remove loose paper. Test for bleed by applying latex to a small area to make sure wallpaper is water fast. If bleed occurs, seal paper with one coat of white shellac reduced with an equal volume of alcohol. Avoid skips when applying shellac. Allow to dry one hour before top coating.
De-gloss or etch the surface by lightly sanding. Apply epoxy polyamide or acrylic urethane topcoat for surfaces that may be exposed to high traffic.
Wash and allow to air dry. Apply either an epoxy or alkyd enamel.
If it is flexible, do not paint it. If stiff, wash with detergent and roughen with sandpaper or steel wool. Prime with solvent based primer.
Scrub with detergent and sand lightly with sandpaper. Prime with alkyd base primer and finish.