Catechol is a slow but hard working developer used as the first developer in a two bath process. In this process the print is immersed in Catechol until the shadow areas are clearly recognisable, this will take between 50 to 90 seconds depending upon dilution. The print is then transferred to the second bath and immersed until the highlight areas are drawn to the required level. The shadows are signficantly deepened and separated and the tone image of the print in the second bath will move towards a cooler nuance. A greater degree of coolness will be achieved in the second bath if the print is left for longer in the first developer. This can be used with great effect to deepen shadows with a warm paper/developer combination. In this case, the print is moved to the second bath as soon as traces of the image appear.