Differences between two runs of SRoll2, one using the best available CO and dust templates, and another using a degraded version of these initial ones (as described in the text) designated as iteration 1. We display the foreground templates evolution: ¹²CO, ¹³CO (two top rows) and I, U, Q dust template (three lower rows). The first column is the difference between the best templates (iteration 0) and the run with the degraded templates (iteration1). SRoll2 is then run with foreground templates built from the sky maps and leakage coefficients from the iteration 1 displayed in the middle column. The results from a third iteration are displayed in the right column.