An aqueous dispersion can contain a) 50-80 wt.-% water, b) 10-30 wt.-% hydrophilic silicon dioxide with a methanol wettability of 0 vol.-% methanol in a methanol-water mixture, c) 2-25 wt.-% alcohol alkoxylate, d) 0.1-20 wt.-% silanol, obtained by the hydrolysis of at least one dialkoxysilane, e) 0.5-4 wt.-%, amine or an amine alcohol, f) 0.1-20 wt.-%, copolymer with side chains containing ethers and esters, and g) 0.1-6.0 wt.-% polyethylene glycol or polypropylene glycol.