... 4, dielectric constant 18.10, insoluble in water, soluble in acid, ammonia, ammonium chloride, dissolved in sodium hydroxide to produce blue color solution ... and other electronic industries, glass, ceramic, enamel, paint industry, agent for take away, fungicides, solar heat absorber surface, reducing tobacco tar ... Acid insoluble ≤%0.010.20.2Cl¯ ≤%0.010.20.2 High quality black copper oxide plating grade