Can FRAMCOLOR 2001 LIGHT&SHINE be processed longer than 20 minutes for lighter, brighter results?

Optimum results are obtained by processing for 20 minutes.

Optimum results are obtained by processing for 20 minutes.  Though longer processing may result in slightly lighter results, swelling/bleeding of the foils, and damage to the hair may also be experienced by processing 40 volume developer under heat for a longer period of time.