The crossword solution for the term 'make blue, say' is 'DYE'. Dyeing is a process of adding color to fabric or other materials. It is done by immersing the material in a DYE bath and allowing the color to be absorbed. The color of the DYE can be changed by adding different chemicals or by changing the temperature of the DYE bath. Dyeing is a common practice in the textile industry and is used to create vibrant colors and patterns on fabrics.