A fresh precipitate can be transformed into colloidal solution by :

Peptization is the process by which an electrolyte in solution disperses recently precipitated particles into colloidal solution. A peptizing agent is the name of the electrolyte that is employed. Sols produced by peptization include, for instance: A little amount of freshly made ferric chloride solution is treated with freshly made ferric hydroxide to produce a dark reddish brown solution. A peptizing agent is ferric chloride.