26-03-2015, 08:42 PM
Paint as a building material seminar report in pdf
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seminar topic paint as a building materials in pdf
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Paint as a building material seminar report in pdf
25-03-2017, 04:29 PM
Paint as a building material
The paint can be described as any fluid material that will spread over a solid surface and will dry or harden to a coherent, dark, adherent skin or film. The paint is used to protect the exterior of a building (against moisture and oxidation) or to embellish its interior.
Properties of paints
• Coherence
• Scatter power
• Drying
• Durability
• Finished
Paint
A wide variety of raw materials are used in the manufacture of paints, but can be grouped according to their function.
Medium, carrier or binder are terms used to refer to oils or resins or combinations of the two that form the basis of all paints. Flaxseed oil is an example of a vegetable oil used as a binder. In all cases it should have the ability to change from a low viscosity liquid to a hard plastic film while also bonding the fine pigment particles together. The actual properties of the binder can be greatly modified by the pigment. Three main properties of the solid film are required:
A) Must have the correct brightness: All binders are bright but have considerable variations.
B) It must adhere to the substrate (the surface to be painted).
C) Requires the correct mechanical properties, this refers to the qualities of the combined film and substrate and includes flexing, scratching the impact of the advertisement.
Pigments are fine insoluble crystalline particles that give color to the paint. They may be organic or inorganic compounds. If the resulting hardened paint film has to be glossy, the pigment should be below the surface. The amount of gloss is determined, but the ratio of pigment to binder, usually measured on a volume basis. Very glossy paints with less pigment have poor binding power, while those that are very dull are underlying. Increasing pigment ratios increases hardness but decreases flexibility. Other properties such as corrosion resistance and exterior durability are affected by the quality and amount of pigment.
Extenders are used to improve other paint properties even though they have little or no pigment value. For example, they can be used to control the amount of brightness. A semi-gloss paint may need so much pigment to achieve the correct brightness characteristics that it would not flush and leave heavy brush marks. The addition of a filler such as the Chinese clay will greatly reduce the cost and, at the same time, improve the viscosity and the finish. Only enough pigment is needed to give color and concealment power. The amount of diluent used varies depending on the paint, but can reach up to 45 percent. Materials used as extenders do not affect color because their refractive index is very similar to that of the soil.
The solvents are volatile liquids added in a step suitable for decreasing the viscosity of the wet paint. They should evaporate very quickly when the paint is applied to a surface so that a high viscosity is obtained and, therefore, it is released from the turns. The solvent may affect the final result and it is vital that the correct type is used for any particular resin system.
Dryers are added to the paints attached to the oil to speed up the drying process. The compounds of lead, manganese or cobalt are the most common.
Cinematographic formation:
The paints can be divided into two groups according to the system by which the hardened film is formed. These are non-convertible and convertible paintings.
The non-convertible system depends entirely on the evaporation of the solvent for its drying process. They have the advantage of simplicity and the ability to dry very fast. However, they tend to produce thin films with poor adhesion and chemical resistance. In addition, they may be dissolved by the original solvent, which causes difficulties to the coating unless spray techniques are used.
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