paint varnishes.pptx
- 1. Introduction Paint is a liquid surface coating. On drying it forms a thin film on the painted surface. Paints are classified as oil paints, water paints, cement paints, bituminous paints and special paints such as fire proof paints, luminous paints, chlorinated rubber paints (for protecting objects against acid fumes), etc. The functions of the paints are: To protect the coated surface against possible stressesmechanical or chemical; deteriorationphysical or environmental; decorate the structure by giving smooth and colourful finish; check penetration of water through R.C.C; To avoid the formation of bacteria and fungus, which are unhygienic and give ugly look to the walls; To avoid the corrosion of the metal structures; To avoid the decay of wood work and to varnish the surface to display it to better advantage.
- 2. Properties of an ideal paint Ease of application good flow out of application marks (e.g. brush-marking) forming a continuous protective film high opacity quick drying corrosion resistance water resistance heat resistance colour stability (i.e. against visible and ultraviolet radiation) abrasion and scratch resistance durability flexibility easily cleaned
- 3. Oil Paint Enamel Paint Emulsion Paint Casein Paint Silicate Paint Plastic Paint Cellulose Paint Synthetic Rubber Paint Anti-Corrosive Paint Aluminium Paint Bituminous Paint Cement Paint Types of paints
- 4. Oil paints Oil paints use white lead as a base, and are applied in three coats: primer, undercoat and finish coat. Oil paints can achieve mat and glossy finishes, while being durable and affordable. They are characterized by their ease of application, and painted surfaces are easy to clean. Use - Oil paint is commonly used in walls, doors, windows and metal structures. Note that oil paint is not suitable for humid conditions, and it takes time to dry completely. Also, before applying oil paints, linseed oil and pigments must be added.
- 5. Enamel Paint This type of paint is produced by adding lead or zinc to varnish. Pigments are added to achieve a wide variety of colors. Enamel paints form hard and glossy coatings, which are easily cleaned. They are characterized by being waterproof and chemically resistant, offering good coverage and color retention. Uses of enamel paint: Interior and exterior walls Wood trims, doors, and flooring Windows Stairs Surfaces like masonry, concrete, plaster, glass, and metals. The main limitations of enamel paint are slow drying, and requiring a titanium coating before application.
- 6. Emulsion Paint Emulsion paints use polyvinyl acetate and polystyrene as binding materials, and they contain driers like cobalt and manganese. They can be water or oil based, and pigments are used to achieve the desired color. Emulsion paints are characterized by their fast drying and hardening, and surfaces can be cleaned easily with water. Once applied, enamel paints offer durability, good color retention, and alkali resistance. Uses interior walls, ceilings and masonry work. Some specialized types of emulsion paints can be used for woodwork.
- 7. Cement Paint Cement paint is available in powder form, which is mixed with water to achieve paint consistency. The base material is white or colored cement, and it may also contain pigments, accelerators and other additives. Cement paint is durable and waterproof, and it is commonly used in rough internal and external surfaces. Consider that cement paint has a long drying time, typically 24 hours. It must also be applied in two coats to prevent dampness issues.
- 8. Bituminous Paint This type of paint is made from dissolved asphalt or tar, which gives it a characteristic black color. It is waterproof and alkali-resistant, but not suitable for applications where it will be exposed to the sun, since it deteriorates. Uses in underwater ironworks, concrete foundations, wooden surfaces and iron pipes. It also helps provide rust resistance when applied in metals.
- 9. Aluminium Paint This type of paint is produced by mixing aluminium particles with oil varnish. It is resistant to corrosion, electricity and weather exposure. Aluminum paint is commonly used for metals and wood, and some specific applications are gas tanks, oil tanks, water pipes and radiators.
- 10. Anti-Corrosive Paint Anticorrosive paint is characterized by its chemical resistance, as implied by its name. It is made from linseed oil, zinc chrome and fine sand. Anticorrosive paint has a black color, and it is durable and affordable. It is normally used for metallic surfaces and pipes.
- 11. Synthetic Rubber Paint This paint is made from dissolved synthetic resins, and can include pigments. It has a moderate cost and its main benefits are chemical resistance, fast drying and weather resistance. Synthetic rubber paint is used for concrete surfaces in general, and this includes fresh concrete.
- 12. Cellulose Paint Cellulose paint is produced from celluloid sheets, amyl acetate and photographic films. Adhesion can be improved by adding castor oil, and surfaces can be easily cleaned and washed once the paint has dried. This type of paint is characterized by its quick drying, smooth finish and hardness, while offering resistance to water, smoke and acids. Thanks to its properties, cellulose paint is commonly used in cars and airplanes. The main disadvantage of cellulose paint is its high price.
- 13. Plastic Paint This paint uses water as a thinner, and it is available in a wide range of colors. It dries very quickly and offers high coverage. Uses Walls and ceilings of auditoriums, showrooms, display rooms, Slabs, Decks Silicate Paint Silicate paint is made from a mixture of silica and resinous substances. Its performance benefits include good adhesion, hardness, heat resistance, and being chemically unreactive with metals. Therefore, this type of paint is commonly used in metal structures.
- 14. Casein Paint This paint is made from casein mixed with white pigments. It is available in powder and paste form, and pigments can be added. Casein paint is commonly used to paint walls, ceilings and wood.
- 15. Varnishes Varnish is a nearly homogeneous solution of resin in oil, alcohol or turpentine. The oil dries with time and the other solvents evaporate leaving behind a solid transparent resin film over the surface. The type of solvent depends upon the type of resin used For rapid drying, driers such as letharage, lead accetate, etc. are used.
- 16. Varnishes provide a protected coating and gloss to the surface and intensify the wood grains. The objects of varnishing a surface are to: 1. Brighten the appearance of the grain in wood. 2. Render brilliancy to the painted surface. 3. Protect painted surface from atmospheric actions. Characteristics of an ideal varnish: 1. It should render the surface glossy. 2. It should dry rapidly and present a finished surface which is uniform in nature and pleasing in appearance. 3. The colour of varnish should not fade away when the surface is exposed to atmospheric actions. 4. The protecting film developed by varnish should be tough, hard and durable. 5. It should not shrink or show cracks after drying.
- 17. Varnish is applied as under: The wood work is made smooth by rubbing it with sand paper and the surface is cleaned. $ is the process of covering the knots in the wood work, using any of the following methods. A coat of red lead ground in water mixed with glue size is applied. After it dries another coat of red lead ground in oil and thinned by boiled turpentine oil is applied. Two coats of varnish prepared by dissolving shellac in methylated sprit or