In this type of colloidal system, the dispersed phase does not have an affinity for the dispersion medium so the colloid is not readily formed. They are also known as irreversible sols as they cannot be reconstituted by simply adding dispersion medium after precipitation. They are unstable and can coagulate easily on adding electrolyte, shaking or heating. Lyophobic colloids can be prepared by special methods and require a stabilising agent.
Hence answer is irrversible.