WHY THE USE OF SODIUM SILICATE IS IMPORTANT FOR AN OUTSTANDING CERAMIC BODY'S DEFLOCCULATION?
Sodium Silicate is an inorganic material that effectively acts within the ceramic body as a fluidifying agent, affecting at the same time other no less relevant aspects.
Which are its most important features and actions?
It make it possible to decrease in the formula the amount of organic elements that, due to their decomposition, can create degassing phenomena during the firing cycle, producing porosity in the final ceramic tile.
For the same reason, the presence of inorganic material reduces the possible formation of the so-called dark heart*** during combustion.
Because of its silica-based structure, Sodium Silicate can also facilitate the glass formation, starting that vitrification and sintering processes that are the basis of the ceramic stoneware’s production.
What about the chemical point of view?
Sodium Silicate (water glass) is a polimeryzed material in water suspension.
It consists of a silicate polymeric chain in anionic form, in which Sodium is the cation.
The de-flocculation process.
Sodium Silicate is then able to start up the three basic mechanisms of the de-flocculation process:
ELECTROSTATIC REPULSION FOR CATION EXCHANGE
Sodium, performing as a monovalent cation, gives life to the cationic exchange with the bivalent and trivalent cations present in the solution. This phenomenon reduces the agglomeration, decreasing viscosity.
STERIC REPULSION & COMPLEXATION
These activities depend on the Silicate and they both affects the system viscosity.
Learn more about de-flocculation process: here.
Is the sodium silicate enough or other mediums are required?
Even if the sodium silicate’s action is evident, it is not completely effective in the de-flocculation process if it is used without adding other synthetic polymers that are able to increase its performance.
This implicitly means that all fluidifiyng agents for ceramic body must possess the right balance in terms of formulation, adapting themselves to the needs of every single production line.
This is the reason why we could say with no doubt that ALL these product are unique and different from each other just like the different production situations.
***Dark heart: dark brown up to black colour area, which is visible in the internal part of the ceramic tile. Its presence is caused by an inadequate oxidation that nevertheless does not compromise the product functionality (unless it is accompanied by a swelling or pealing effect).
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