Originally Posted by
Gresp15C
I'd be surprised if the original surface roughness is an issue after the discs are worn in.
I had a set that worked fine for a few dozen miles, then squealed when cold or wet. Returned them & roughed up the replacements with 100 grit then 150 grit followed by brake parts cleaning them.
Same pads as before, replacement discs & no noise. Have over 1000 miles on them.
The first set as well as the replacements had a very smooth almost polished surface. That to me, exacerbates glazing or a very low resistance to achieve necessary friction needed. YMMV