Yeah, it just stabs at the metal if it can't conduct straight away.
A flap disc will be much easier to use than a grinding disc, as it'll "spare" more of the steel, as opposed to making it (even) thinner!
All the Best,
I'd already hit it with a prep disc, but this was to remove the paint not specifically trying to brighten up the metal.
Do you find a flap disc cuts down welds faster than a grinding a normal disk? The welds I did on the car today were pretty ugly and will need a lot of grinding down and it seemed to be taking an age even with a decent Norton grinding disk. I've got some flap discs in a variety of grits, I can try them tomorrow.