Improvements in the Manufacture and Production of Colouring Matters and of Lakes therefrom.

摘要

A soluble compound is prepared by treating the dye Lithol Red R with neutral ammonium sulphite solution. Lakes are prepared by decomposing this product by heating with alkali carbonate in the presence of a substratum. Other monoazo pigment dyes yield similar products with neutral ammonium sulphite. Specification 8065/13 is referred to.