If there is a precipitate there is a basic dye, if not, an acid dye.
The goods may advantageously be bottomed with an acid dye or a dye-wood extract, and then finished with basic dyes.
acid dye n.
Any of a class of dyes that contain acidic groups, usually in the form of sodium or potassium salts, and are used in staining cytoplasm and various acidophilic structures of cells or tissues. Also called acid stain.