Thanks for the hint that it is possible to have more than one settings for the unclog-procedure.
The kind of black ink depends on the choosen paper.
But I have a slight problem
with my Epson 4990.
Switching from one black ink to the other enforces a cleaning cycle, that spoils about 1.5 ml of ink to the garbage.
So if I do the unclog for both inks it is quite pricy.
Therefor I do this unclog-procedure molstly just for one of the blacks
Winfried