I do the same and never have any issuesWhat do you mean by blade off. Do you use a squeegee ? I never get streaks on ours all i do is towel dry with micro fibre drying towel
We use blades on fresh paintwork on a daily basis, we wash cars before the customer collects them and we blade them down afterwards with no ill effects.Your call if a blade works for you all good .I personally wouldn't use a blade on any cars paintwork
With washing tools key is keeping them clean .
Cheers Cliff.