Rasahridayatantra 8.2.1

8.2.1

atha nijakarme varṇaṃ na jahāti yadā sa rajyate rāgaiḥ /
kramaśo hi vakṣyamāṇairnirṇikto raṃjanaṃ kurute //

Now, when it does not lose its color during its work, it is colored by coloring agents;
properly cleansed, it effects coloration through those that will be described in due order.