Abstract: An electrodeposition coating method characterized in that in electrodeposition coating of a water soluble composition of a polyimide precursor which is prepared by using 1,2,3,4-butanetetracarboxylic acid or its imide-forming derivative and a diamine and has a percentage of residual acid value of 30 to 3%, there is added previously a water soluble solvent selected from the group consisting of an alcoholic solvent, N-methyl-2-pyrrolidone, dimethylformamide and dimethylacetamide to the above-mentioned composition, and an electrodeposition coating agent used therefor. There can be provided the electrodeposition coating method practicable for the use of a water soluble polyimide composition which is capable of forming a uniform baked coating film having a continuous surface and being excellent in adhesivity to substrate and in toughness.

Abstract: A method for coating steel structures in water which comprisescoating as a first layer an underwater-curable composition comprising(1) a two-pack resin blend system comprising(a) a blend system comprising an epoxy-based resin, and(b) a blend system comprising an underwater-curable curing agent capable of hardening the epoxy-based resin blend system, and(2) from 5 to 75% by weight, based on the total weight of the underwater-curable composition, of a metal powder having an ionization tendency greater than that of iron,on the steel structures, andcoating an underwater-curable composition comprising the two-pack resin blend system and a coloring pigment on the first layer as a second layer.