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1. MECHANISM

   • degradation of bulk matter to the size required (powderization - comminution)
   • aggregation of small molecules or ions (condensation process).

2. METHOD

   • CONDENSATION
     • CHEMICAL METHOD
       • HYDROLYSIS
       • REDUCTION
       • OXIDATION
       • DOUBLE DECOMPOSITION
     • PHYSICAL METHOD
       • EXCHANGE SOLVENT
         • A true solution in mixed with an excess of another solvent in which the solute is insoluble but the solvent is miscible. For e.g., a solution of sulphur in alcohol mixed with excess of water results in a colloidal sol of sulphur.
       • BY EXCESSIVE COOLING
         • A colloidal sol of ice in an organic solvent such as CHCl3 or ether is obtained by freezing a solution of water in the solvent. The molecules of water, which can no longer be held in solution separately come together to form particles of colloidal size.
   • DISPERSION- REDUCTIONOF LARGER PARTICLE TO COLLOIDAL SIZE
     • PEPTIZATION METHOD
       •  Is a process of converting a precipitate into a colloidal sol by shaking it with the dispersion medium, in the presence of a small amount of electrolyte.  The electrolyte used is called the peptizing agent.  This method is used to convert a freshly prepared precipitate into a colloidal sol.
     • ELECTRICAL DISINTEGRATION ( BRIDIG'S ARC METHOD)
       • In this method, an electric arc is struck between electrodes of the metal immersed in the dispersion medium. The intense heat produced by the arc vaporizes the metal, which then condenses to form particles of colloidal size
     • MECHANICAL DISPERSION METHOD (MECHANICAL GRINDING)
       • Feed powdered solid and liquid and solid into colloidmill. • Colloid mill consist of metal plate place together and rotating at high speed in opposite direction • Shearing action of plates reduces the size of solid particles to form colloidal solution Example – production of colloidal graphite (lubricant) - printing ink.