The precursors of the color pigments can be easily dissolved into the dissolving tank. However, depending upon the formulations, these precursors are usually based upon the Naphtha with the addition of sodium hydroxide and water as solvents. This tank can also be implemented for dissolving the smelt by blending hot smelt stream with a cold weak wash stream. It is equipped with an agitator for ensuring the even and uniform mixing of substances because of their addition. The presence of measuring system ensures reliable values to be fed to the control systems.