A. Porosity

SYLYSIA® has a sponge-like structure with different degrees of porosity that varies from low (0,4 ml/g) to high (1,8 ml/g) pore volumes.
Silica with low pore volume has lower absorption capacity for liquids and therefore has in general little influence of viscosity. Higher porosity silica usually offers higher matting efficiency due to their higher volume (number of particles) per unit weight.

B. Surface Treatment

SYLYSIA® grades are characterized by high specific surface area (300-700 m2/g).
The surface treatment of silica is done in order to improve the performance in various applications.
The treatment can be made by physical coating of the particles or by chemical reaction involving the silanol groups (Si-OH) of the silica particles.
Most often, an organic treatment is used for SYLYSIA® coating in order to fullfil specific needs, for example: prevention of the formation of a hard sediment and improvement of the mechanical properties of the applied paint film.

C. Particle Size

The particle size of a silica grade is relevant to matting efficiency smoothness and transparency of the applied paint film.
In most applications, the selection of a suitable silica grade with a specific particle size is governed by the thickness of the applied film.
For illustration, the table in the efficiency/particle size section compares the relative performance of 3 different grades having identical pore volume, organic surface treatment but different Average Particle Sizes.