Etch bleaching liquid.

摘要

An aqueous acidic etch-bleach solution comprising hydrogen peroxide, iron(III)ions and inorganic anions that form a silver salt having a solubility product not greater than 1×10<Sup>-8</Sup> determined in water at 20°C, characterized in that said solution contains in dissolved state as combination of H<Sub>2</Sub>O<Sub>2</Sub>- stabilizing agents citric acid and a polymer containing alkylene oxide units. Said combination provides a solution to the problem of producing ecologically acceptable and stable H<Sub>2</Sub>O<Sub>2</Sub>-solutions containing iron(III)ions.

The etch-bleach solution is useful for the production of coloured relief images and lithographic printing plates starting from silver images.