Wood preservative based on polymeric nitrogen compounds and metal-fixing acids

A water-soluble wood preservative comprising:

• (a) a wood-preserving effective mount of a metal compound selected from the group consisting of copper compounds, zinc compounds and a mixture thereof;
• (b) a metal-fixing acid selected from the group consisting of aliphatic C.sub.5-20 -carboxylic acids, halogen substituted C.sub.5-20 -carboxylic acids, amino substituted C.sub.5-20 -carboxylic acids, alkoxy substituted C.sub.5-20 -carboxylic acids, aliphatic C.sub.5-20 -dicarboxylic acids aminohydroxy C.sub.5-20 -carboxylic acids, 2-mercaptopyridine C-oxide, 2-hydroxypyridine N-oxide, dehydroacetic acid, cycloalkyl carboxylic acids, aryl carboxylic acids, polycarboxylic acids, and heterocyclic carboxylic acids;
• and
• (c) a washout-reducing effective amount of a polyethyleneimine having a degree of polymerization between 50 and 1000.