Each batch of ingredients is thoroughly mixed in

This preview shows page 8 - 12 out of 18 pages.

consistency. Each batch of ingredients is thoroughly mixed in large, stirred containers with the required additives. Amounts ranging up to 40 000 cubic decimeter of paint may be made in a single batch.
Image of page 8

Subscribe to view the full document.

TYPES OF PAINTS Oil Paints These are the traditional type having a linseed oil medium. They are respectively termed as primes, undercoats and finishing coats. This paint is cheap and easy to apply and it possesses good opacity and low glow. It consists of various coats: Priming Coat : - Linseed oil, white lead, a small amount of red lead and extender (a white pigment used to increase bulk, prevent sedimentation and improve spreading) - The lead base is particularly suitable for external work; - Leadless pigments are for internal use. Under Coat - Linseed oil, white lead(tinted if required) and has a high quality drying oil. Finishing Coat - Oil varnish, pigments of desired colour and perhaps extenders, and thinnerrs; finishes vary from flat to oil-gloss. Synthetic Paints The medium for these is a chemical compound, one type being an oil modified alkyd resin. They have the advantages over oil paints in setting more quickly and offering greater durability where corrosion is a danger.
Image of page 9
They also have a better flow and are easier to apply. Drying is by evaporation of the solvent, by oxidation and chemical change. Emulsion Paints An emulsion paint has the pigments and the medium dispersed as small globules in water. Oil, synthetic resin and bitumen are common medium. The different emulsion paints are alkyd, bitumen, polyvinyl acetate and styrene emulsions. They are used mainly on walls surfaces. Alkyd emulsion paints contain pigments, oil, and synthetic resins, they give a flat finish. Bitumen emulsions are those of bitumen in water plus pigments and extenders. They are for use on asphalt and bituminous surfaces. Cellulose Paints These are synthetically reproduced from cellulose compounds and most of them have to be applied as a spray for they dry very quickly by evaporation of the solvent. Apart from some kinds metal powders (aluminum and bronze) they are not satisfactory for general building work but can be used for furniture and fittings in houses. They are widely used in the motor car industry. Varnishes
Image of page 10

Subscribe to view the full document.

These are two kinds of Varnish, namely: a. SPIRIT VARNISH: Spirit varnish is a solution of shellac and spirit resins dissolved in commercial alcohol (methylated spirits). They are only suitable for internals surfaces like furniture (e.g. in French polishing). Polyurethane varnish is a type of resin varnish producing a very durable finish. b. OIL VARNISH: They contain linseed oil or other drying oils, dryers, synthetic or natural resins and solvents such as white spirit or turpentine. They dry by evaporation of the solvent and oxidation of the oil.
Image of page 11
Image of page 12
  • Summer '17
  • Engr. Arnolfo Arcibal

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern