Talc is used as an extender and suspending agent in oil paints.Extender: a) The refractive indices of talc and linseed oil being similar, addition of the former does not modify the opacity or hiding power of the composite paint. Due to its platy structure, the powders of talc are made up of micro-flakes with large total surface area enabling the flakes to securely stick to the surface coated and allowing the paint to level out after application which is called FLATTERING EFFECT. This effect along with smooth surface of the flakes, pearly lustre and their durability, ensures a smooth, even, pleasing and durable finish of the painted surface. b) Due to its white colour, talc does not affect the colour of the main pigment component of the paint. c) its softness facilitates easy brushing without any abrasive effect. d) Resistance to ultraviolet light is an additional advantage when the painted surface is exposed to sun.
- Suspending agent: In this application the fibrous crystalline type of talc in powder form makes a good low-cost substitute of some expensive materials like china clay.
- Fine-sized fibers of talc trap and hold the primary pigment particles enabling the latter to remain in suspension long enough to facilitate brushing.
- Smooth surface, pearly lustre and durability of talc will ensure a smooth, even, pleasing and durable finish of the painted surface.
- Its resistance to ultraviolet light is an additional advantage when the painted surface is exposed to sun.