TALC

Talc is a soft, nonabrasive, inert mineral that can be ground easily (flaky habit) to form white and bright (>78 GE) fine to micronized powder that acts as a functional filler (paint; plastics; paper; rubber; adhesives; joint compounds; stucco; pharmaceuticals). Additional advantages include its high oil and grease absorption capabilities (organophilic/hydrophobic) [cosmetics and pharmaceuticals; pitch-control in pulp; paper filler and coater; dusting and mold-release agent; bitumen filler] and its flaky habit provides structural strength, pigmentation, opacity, rheology, viscosity, and corrosion and weathering resistance [paint; specialty plastics; various rubber compounds]

In Paint, talc has a reinforcing effect, controls viscosity, prevents sagging of paint films, improves suspension characteristics, and because of its large surface area (>12 m²/g) dictates gloss.

In Plastics, talc has a strong reinforcing effect.

In Pharmaceuticals and cosmetics talc’s greasy feel [lubricant or glident], fragrance retention [talcum powder, soaps, creams, and lotions] and hiding powder are useful characteristics.

In roofing products, talc acts as a stabilizer for the melted asphalt thus increasing resistance to fire and weathering.

In ceramics, talc’s high fusion point (heat-stable up to 900°C), fluxing action (due to MgO), and predictive thermal expansion allow lower firing temperatures and shorter firing cycles to be achieved.

Steatite is a massive, cryptocrystalline form of Talc which can be machined easily, has uniform low shrinkage in all directions, and high electrical resistivity when fired [electronic insulators].

Soapstone is a massive green to gray to a black mixture of talc and magnesite that is aesthetically pleasing and can be cut with a knife or machined, resists weathering and acid and alkali attack, is non-toxic and non-absorbent, retains heat, has a melting point of 1630°C and can be polished.

Ceramic grade: min 30% MgO and 60% SiO₂

Cosmetic grade: max 0.1% water soluble substances, 6% acid-soluble substances, 6% LOI @ 1000°C.

Paint grade: min 88% Mg & Ca Silicate, Max CaO, 1% water-soluble matter, 1% moisture and other volatiles, 7% LOI @ 1000°C