In the pharmaceutical industry, the main criteria for use of talc are its white colour, mechanical strength, platy structure, low refractive index, chemical inertness and good lubricity (due to smoothness).
Its applications are as follows:
- It is used as a lubricant to facilitate tablets or capsules to glide along during their manufacture. Talc constitutes only 1-4% of the material.
- It is used as a carrier of dusting powders by virtue of the large surface area provided by its plates to which dust particles adhere. Talc constitutes 90-99% of the material However, it is not suitable for use for dusting surgical gloves because when the gloves are in contact with peritoneal cavities or open wounds, talc causes irritation.
- It finds application as a filler in some types of tablets. However, due to slipperiness and hydrophobic nature, particles of talc tend to disintegrate and not hold together often creating problems.
- It can be used as a structural strengthening agent in film coating because: (i) its plates facilitate formation of smooth films, and (ii) colours used in the tablets remain unaffected due to the low refractive index of talc.
A very high degree of purity is required and natural talc has to be processed for removing impurities like iron oxide, dolomite and other carbonate materials and carbon.