Method for treating a surface with a treatment gel and treatment gel

The method for treating a surface with a treatment gel, said method comprising in this order the following steps:

• applying a treatment gel on the surface to be treated, said treatment gel consisting of a colloidal solution comprising:
• 5 to 25% by weight, based on the weight of the gel, of a mixture of pyrogenated silica and precipitated silica,
• 0.5 to 4 mol/l of an active treatment agent, and
• optionally from 0.05 to 1 mol/l of an oxidizing agent having a normal oxidation-reduction potential E0 larger than 1.4 V in a strong acid medium or of the reduced form of this oxidizing agent,
• maintaining the treatment gel on the surface to be treated at a temperature and relative humidity such that the gel dries and that it has the time to treat the surface before forming a dry and solid residue, and
• removing the dry and solid residue from the treated surface.