U.S. 8,128,996 B2
Akzo Nobel N.V. has received a patent for a process for primer coating a steel substrate comprised of coating a steel substrate with a shop primer coating comprised of a silica binder, the binder is comprised of an aqueous silica sol having a SiO2/M2O mole ratio, wherein M represents the total of alkali metal and ammonium ions, of at least 25:1, drying the primer coating at a temperature of from 10° C to 60° C and, after the primer coating has dried to the extent that it is touch dry, immersing the coated substrate in water and/or storing it in an atmosphere with a relative humidity of at least 50%, wherein the coating has a dry film thickness of less than 40 microns, and wherein the primer coating optionally is comprised of alkali metal silicate at a weight ratio of alkali metal silicate to silica sol of less than 0.1; and, wherein the silica sol further contains an organic resin, in an amount of from 1% to 35% by weight, based on solid binder, wherein the organic resin is a latex.