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Wednesday, February 10, 2010

PAINTS | ARCHITECT EXPLAINS

Paint is used to protect (Eg. covering of metal to retard corrosion, and the painting of a house to help protect it from nature's elements), preserve, decorate (by adding color), or add functionality to an object or  surface by covering it with a pigmented coating. 






COMPOSITION OF PAINT:
Physically, paint is a mixture of four important elements: Pigments, Additives, Binders and Solvents
  • Pigments render color and opacity to the paint.
  • Additives endow the paint with special properties such as resistance to fungus, rust etc.
  • Binders hold the paint together and also bind it to the surface being painted, thus promoting durability.
  • Solvents give a paint its flowing property, enabling brushing/rolling on a surface. 


Depending on the solvent used, paints can be categorized as:
  • Water-based (where water is the solvent), e.g. plastic emulsions and distempers or 
  • Oil-based (where Thinner, a petroleum by-product is the solvent) e.g. enamels and wood finishes.
APPLICATION OF PAINTS:
Paint can be applied as a solid, a gaseous suspension or as a liquid. Techniques vary depending on the practical or artistic results desired.
  • Solid Paint - By "powder coating" an object. Solid Paint is usually used in industrial and automotive applications wherein, the paint is applied as a very fine powder, then baked at high temperature. This melts the powder and causes it to adhere (stick) to the surface.
  • Gaseous Paint - By "spray painting" an object. The paint is atomized by the force of compressed air or by high pressure compression of the paint itself, which results in the paint being turned into small droplets which travel to the article which is to be painted. Paint application by spray is the most popular method because of the following advantages:
  •  Liquid Paint - is applied by direct application using brushes, paint rollers, blades, other instruments, or body parts as in fingerpainting, where the paint is applied by hand. Paint may also be applied by flipping the paint, dripping, or by dipping an object in paint.

TYPES OF PAINTS USED IN BUILDINGS:
For painting your home, there are basically 5 types of paints to consider.
  1. Exterior Paints,
  2. Interior Paints,
  3. Metal Paints,
  4. Wood Finishes and
  5. Special Application Paints.
1. EXTERIOR PAINTS:
  • Cement Paints - Cement paints are an economical exterior wall finish that assure effective  medium range protection against the weather. It is resistant to fungus and algae and protects the buildings from varying outside weather conditions. It is water based paints and easy to apply. They are available in a range of standard colours, in matt finish and are adequately fade-resistant. A good application of cement  paint after proper surface preparation, can stretch your  repainting cycle to 5 years.
  • Exterior Emulsions - Emulsions also known as 'Plastic paints', have water as a base along with a fine dispersion of acrylic and vinyl resins which on drying, make them exceptionally hard wearing, tough and durable. Special  additives make them exceptionally resistant to algae, fungus and atmospheric erosion. And they are available in colours of every hue and are fade resistant for years. They are an ideal choice for exteriors as they create a tough, enduring coating that can last for 4-5 years.
  • Textured Plasters - Also emulsion based exterior finishing coats, Textured Plasters provide even stronger protection than Emulsions, besides unusual visual appeal. Their thick surface can be designer-patterned by sponging, stippling or patterned rollers. Washable over and over, their attractive colours and patterns combine beauty with heavy duty protection.
2. INTERIOR PAINTS:
  • Distempers - The traditional economy paints, they can produce a perfectly satisfactory finish at reasonable cost, given proper application and workmanship. However, their lifecycle is shorter. Dry Distempers (which come in powder form) and Oil Bound / Synthetic Distempers are not washable. Acrylic Distempers, being partly based on acrylic resins, produce greater smoothness and washability. Properly maintained, they keep their good looks for 3 to 4 years.
  • Interior Emulsions (Plastic Paints) - These are based on a fine dispersion of resin in a solvent, which on drying, creates a remarkably tough, adherent, durable coating. Special additives in emulsions give them an incomparably smooth finish, in beautiful shades that last for years. Other special properties keep them free from fungus and algae. As they are resistant to water and chemicals, washing makes them smile again. They come in three categories namely:
  • Silk Emulsions (Premium Acrylic Emulsions) -  with silky smoothness and a luxurious silk-like finish. Their very high acrylic resin content enhances durability, and creates reflectance and smoothness of such a high order that dust cannot settle on it. A ‘silk’ wall looks fresh many years later.
  • Regular Emulsions - produce a smooth eggshell finish, in an equally wide choice of colours, and have almost the same durability as Silk. Combining Silk and Regular Emulsions judiciously could give your painting project just the right balance between great looks and economy.
  • Economy Emulsions - offer the basic strengths of emulsion paint but, at economy prices. They are still a generation ahead of Distempers on durability, washability, fade-resistance and smoothness.
3. METAL PAINTS ( ENAMELS):
Doors and windows, metal grills and furniture have a common type of paint for coating them, namely the Enamel paint.These are not water based paints but oil-based paints.
  • Synthetic Enamels - are alkyd resin based formulations that work equally well on wood, metal and even walls. Besides a brilliant and smooth finish, they also provide very good protection against atmospheric corrosion, including rusting.
  • Premium Enamels - are extremely tough, provide long protection and mirror-like finish. They withstand extreme climatic changes and can be used both inside and outside.
  • General Purpose Enamels - are also tough, provide a durable and pleasing, though less glossy finish. They are not recommended for exterior surfaces. Two coats of a general purpose enamel give good long term protection for hardworking surfaces where durability and economy are chiefly wanted.
4. WOOD FINISHES:
  • Poly-urethane (PU) - are the modern alternative to old-fashioned varnishes. These are synthetic, and provide an extremely tough, transparent protective coating which allow the beauty of the wood grains to show through. But unlike varnishes, they are to easy to maintain and stand up to rigorous wear and tear, heat and liquid and stains. Available in both matt and glossy finishes, they  can be used on a wide variety of wooden surfaces including furniture and cane.
5. SPECIAL APPLICATION PAINTS
  • Flat Oil Paint for Bathrooms and Kitchens - Flat Oil Paint is recommended over emulsion based wall paint to correct staining and flaking, especially in damp and greasy areas like Bathrooms and Kitchens. The advantage is that they can be wiped down with a damp cloth to keep them clean. Condensation of moisture, fumes, grease stains, etc. cause paint breakdown, flaking and mould infection.
  • Anti-termite protection for wood - It is absolutely essential to pre-treat all wooden surfaces with a transparent Melamine coating, brushed onto bare wood to guard against termites, wood borers, etc. Its greatest advantage is that it allows subsequent overpainting with paints, synthetic finishes and polishes.
  • Bituminous Paint for water tanks - Concrete and galvanised iron water tanks are susceptible to algae and fungus attack, besides corrosion. Non-toxic Bituminous paint will keep the inside of the water tank free of algae, fungus and corrosion.
  • Aluminium Paint - The reflective silver-like lustre of Aluminium paint serves as an external protection for the Water tanks as well as reduces internal temperatures. Aluminium Paint can also be used effectively to increase the life of gas-holders in kitchens.
TYPES OF FINISHES:
When Surface Coatings (Top coat of Paint) dry, they produce films with varying degree of sheen. The range extends from Flat or Matt finishes which have no sheen, through increasing degree of Luster to high gloss finishes. Based on the reflectance level of the dried film of paint we can classify the finish in the following four categories:
  • Matt: It is the kind of finish, which has the lowest level of gloss. When the gloss on a panel painted with a Matt finish paint is measured in a glossometer at 60-degree angle, the reading is less than 5.
  • Satin or Egg-shell: This finish has silk like gloss, explains the name Satin finish. When the gloss on a panel painted with a Satin finish paint is measured in a glossometer at 60-degree angle, the reading is 6-20.
  • Semi-gloss: This finish has more gloss than a satin finish. When the gloss on a panel painted with a Semi-Gloss finish paint is measured in a glossometer at 60-degree angle, the reading is 21-70.
  • Glossy: This is the finish with highest level of gloss. When the gloss on a panel painted with a Gloss finish paint is measured in a glossometer at 60-degree angle, the reading is more than 70.
STORAGE OF PAINTS:
  • It is difficult to reseal the paint container and store the paint for a long period of time. It should be stored upside down, for a good seal. Storage should be in a cool dry place, protected from freezing.
  • Interior/exterior house paints tend to separate when stored, the heavier components settling to the bottom. Therefore, it should be mixed before use, with a flat wooden stick or a paint mixing accessory.
DISPOSAL:
  • Liquid Paint - Proper disposal of left over paint is a challenge. To dispose of paint, one method is to dry it, either by leaving the lid off until it solidifies or by pouring it into a disposable drying device. Once dry, the paint may be discarded with normal trash.
  • Wet-oil based Paint - should be treated as hazardous waste, and disposed of according to local regulations.
  • Recycling Paint- Sometimes it can be recycled: Old paint may be usable for a primer coat or an intermediate coat, and paints of similar chemistry can be mixed to make a larger amount of a uniform colour.

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