Which of the following varnishes are prepared by dissolving hardest gums like copal in drying oil and volatile solvents?

Explanation

Explanation: Varnishes are a homogeneous colloidal solution of natural or synthetic resin in spirit or oil. The varnish is used for both protection and decoration of metal surfaces. Types of varnishes: Sprit Varnish: It is prepared by dissolving natural or synthetic resins in a volatile solvent (spirit). This type of varnish dries just by the evaporation of the solvent. The film formed is brittle and strong. It is used for polishing wooden surfaces. Oil Varnish: It is prepared by dissolving natural or synthetic resins in drying oil and volatile solvents . This type of varnish dries by the evaporation of the solvent followed by oxidation and polymerisation of the drying oil. Oil varnishes dry slowly, but the film is hard. It is used for interior and exterior works. Important Points Characteristics of a good varnish: It should be soft It should produce a shiny and glossy film on drying It should dry quickly It should not shrink or crack after drying