Paints and Varnishes By Engr. Dr. Attaullah Shah

Paints Preserve material Gives required color to surface applied. Uses: Preserve material Gives required color to surface applied. Aesthetics Oil Paints are most commonly used. Oil Paints: Following constituents: Base: Iron oxides, white lead, zinc oxide, red lead. Vehicle: Linseed oils (Pale yellow). Driers: Added to dry quickly and harder. Red lead. Thinner: To reduce viscosity of paints. Pigments, color or strains. Spirit of Turpentine Coloring pigments: To give the desired color

Preparation of Paint: Ready Mixed Paints: The base ingredients are thoroughly ground in oil and thinned by the addition of oil and turpentine. The pigments are separately mixed with oil and Turpentine added to make it fluid. The two mixtures of base and pigments are added and turpentine added to make it workable. The grinding of base is done with the grinding roller mill Before application of the paint, the surface is scrapped cleaned. Ready Mixed Paints: Which have been mixed by the Manufacturers. Burgers, Robbialic, ICI Dulux etc.

Proportioning of Ingredients of Paints It depends on the following factors: Nature of Material to be painted. Wood, Iron Types of Surface Nature and Appearance of the work Climatic conditions Skill of the painter Quality of ingredients. Nature of Coats applied. Anything else in your mind?

Aluminum Paints Finely ground Aluminum suspended in a medium of slowly drying Costly and used for decorative purposes. Protects Irons and steels from corrosion. Used for painting marine works. Resists heat and good for radiators and hot water pipes.

Water Paints The medium is water. Certain amount of glue added to form emulsion. Used only for inferior works. For decoration of exterior works and stucco surfaces.

Distempers Water paints having oil and water as thinning agent. Glue starch or Casein resin used as base together with a pigment to suit the required color. For base whiting chalk is used as base. Distempers are used for application of interior works except wood and iron. Oil bound distempers are used in the form of solid pastes and thinned with water before use. Distempers are washable.

Varnishes Gives brilliance to the surface. Generally transparent Resins are dissolved in rapidly solvent such as Turpentine, oil etc. Varnishes dry quickly and give hard surface to protect them from harsh weather. Generally applied to wood, furniture and building works. Sometimes used over paint work for shining.

Resins Obtained from natural gums of various trees. The following resins are used for preparation of varnishes. Shellac: Obtained from the trees of pipal, generally known as “Lakh” Amber: Yellow hard transparent durable substance found between the beds of woods and coals. Copal or Gum Anime Kauri Dammar