Don't quote me but when I started afp many years ago I was told not to use the brush on the paintwork... Obviously the reasons above but also it erodes the lacquer after a sustained period... I cannot verify whether this is true or not because I followed the advise.. So I use pure water just to rinse..
Cars don't have lacquer anymore bud.
If I ever get the chance to wash my motor I do final rinse with pure, like a lot of lads on here.
Rarely do now though.
Shame, used to be one of life's little pleasures for me.
By lacquer he probably means the clear coat
I would only use a very clean flocked brush to clean the cars paintwork, and only then if wasn't overly dirty.
I tend to just use a DI rinse, leaves a fantastic finish, no chamois needed.