Thin corrosion protective coatings incorporating polyamidoamine polymers

An anti-corrosion metal pretreatment composition comprising components:

• a) from 10 to 2000 ppm of dissolved Group IVB metal;
• b) from 1 to 50 ppm of dissolved copper;
• c) from 1 to 5000 ppm of at least one nitrogen containing organic polyamidopolyamine polymer which is a reaction product resulting from a polymerization reaction of alkyldiamines, polyamines and/or polyalkylpolyamines with a carboxylic acid or carboxylic acid derivative, dissolved and/or dispersed in the composition and comprising a plurality of organic amide and amine functional groups and optionally imidazoline functional groups, wherein the at least one polyamidopolyamine polymer comprises a mixture of two polyamidopolyamine polymers, wherein a first polyamidopolyamine polymer has a number average molecular weight of from about 200 to 400 Daltons and a second polyamidopolyamine polymer, different from the first, has a weight average molecular weight ranging from 200 to 10,000 Daltons;
• and
• d) water;
• said anti-corrosion metal pretreatment composition having a pH of from 2 to 6.