Protection of Colloids and Gold Number
• Lyophilic sols are more stable than lyophobic sols.
• Lyophobic sols can be easily coagulated by the addition of small quantity of an electrolyte.
• When a lyophilic sol is added to any lyophobic sol, it becomes less sensitive towards electrolytes. Thus, lyophilic colloids can prevent the coagulation of any lyophobic sol.
“The phenomenon of preventing the coagulation of a lyophobic sol due to the addition of some lyophilic colloid is called sol protection or protection of colloids.”
• The protecting power of different protective (lyophilic) colloids is different. The efficiency of any protective colloid is expressed in terms of gold number.