PURPOSE: To improve shelf stability of an inorganic composition by blending a specific condensed composition with an alkylalkoxysilane.

CONSTITUTION: (A) A condensed composition is obtained by mixing 1mol of a tetraalkoxysilane of the formula Si(OR)4 (R is a 1-5C alkyl) with 2-8mol of basic water having pH10.0 to pH12.0 and 10-30mol of an organic solvent. (B) Another condensed composition is obtained by mixing 1mol of a tetraalkoxysilane of the formula Si(OR1)4 (R1 is R) with 3-8mol of acidic water having pH0 to pH2.6 and 10-30mol of an organic solvent. (C) A condensed composition is obtained by mixing the component A with the component B in the weight ratio of the components A/B of 0.4-2.4. The component C is mixed with an alkylalkoxysilane of the formula (R2)nSi(OR3)4-n (R2 and R3 are each a 1-5C alkyl; (n) is 1-3) in an amount to give 0.1-2mol of the alkylalkoxysilane based on 1mol of the total of the tetraalkoxysilanes used in the production of the composition C.