Texas talc (left) quickly absorbs all the water poured on it. Montana talc (right) resists whetting of the particles much more, the water is just sitting on top and has not penetrated at all.
The Montana material is more pure, and it is a platy talc. Talc platelets expose broad basal water repellent surfaces that are difficult for water to wet. When these fine plates settle parallel to the surface, they can form a tightly packed, water-repellent layer with very small pore entrances. Surface tension and trapped air then prevent water from entering, so it remains pooled on top.
The Texas is chemically and physically different. It contains appreciably more calcium-bearing material and other non-talc components. It also has rounder, fluffier and substantially coarser particles. These characteristics provide larger, better-connected pore passages and more readily wetted mineral surfaces. Once water enters those pores, capillary suction quickly pulls it through the powder.
| Materials |
Talc
A source of MgO for ceramic glazes, a flux or thermal expansion additive in clay bodies, also used in the manufacture of cordierite. |
| Materials |
Pioneer 2661 Talc
|
| Materials |
Natural Talc C-98
|
| Glossary |
Permeability
In ceramics, the permeability of clay slurries and plastics determines the rate as which water can move through the matrix |
![]() PayPal | No tracking, No ads, No paywall, No transient content! Just organized, concise information constantly updated and improved. Was this helpful? Consider supporting me. |
Buy me a coffee and we can talk