Grain structure
We offer both types
Usually, only two types of amorphous silica are used for polishing suspensions.
Fumed Silica
Is manufactured in an oxidation process in a flame. This type of silica primarily contains particles with a diameter of nano-size, which may, however, form aggregates of varying sizes. In our suspensions, the mean aggregate size is 0.2 µm to 0.1 µm, which is considered the appropriate size for final polishing. Sedimentation may occur and the bottle should therefore be carefully shaken before use.
Colloid Silica
is manufactured as an aqueous precipitation which produces relatively few aggregates as compared to the oxidation process described above. The most frequent particle size is 20-100 nm. Our colloidal silica suspension has been ultrafiltered before bottling in order to remove as many aggregates as possible, and the particle size in this product (D50) is approx. 50 nm.
This illustration shows the difference between fumed (particle aggregates) and colloidal (individual particles) silica:
On to pH