Pyrolysis resistant coating finish

A coating solution made from a mixture of at least one silane and at least one polysiloxane which can be hardened on a substrate by hydrolysis and condensation to give a coating on the substrate, wherein the at least one silane is of general formula RxSi(OR′)4-x and the at least one polysiloxane is of general formula [R2SiO]y or R3Si-(O-SiR2)Y-O-SiR3, where R independently=alkyl, aryl, arylalkyl, alkylaryl or H, Rprime independently=H, methyl, ethyl, n- or i-propyl, n-, iso-, sec.- or tert.-butyl, x=0 or 1 (for the first silane), x=0, 1, 2, 3 or 4 (for each further silane) and y=a whole number of at least 2, wherein the coating solution includes at least one alkali or earth alkali oxide or hydroxide.