Disclosed are a process for producing a suspension of hydrophobic oxidic particles which has a defined, adjustable viscosity, which comprises suspending low structured hydrophobic oxidic particles in at least one organic suspension agent and then adding from 0.05% to 15% by weight based on the suspension medium of high structured hydrophobic oxidic particles, a suspension of hydrophobic oxidic particles which has a defined, adjustable viscosity and the use thereof for producing soil and water repellent coatings on articles.