Coating solution for metal surfaces

摘要

In an acidic aqueous coating solution which contains zirconium, hafnium or titanium, and fluoride and which is effective in forming on an aluminum surface a non-chromate coating to which overlying coatings adhere tightly and which is corrosion resistant and resists being discolored when subjected to hot water, the improvement comprising including in said coating solution a surfactant in an amount such that a coating formed from the surfactant-containing coating solution has an improved tendency to resist being discolored by hot water.