Start at 40 grit to take a weld bead down fast, then 60 and 80 to remove the scratches the previous grit left, then 120 for a surface ready to paint or polish. Each grit only removes the marks of the one before it.
The temptation is to stay on 40 until the weld is flat and stop there. What you have then is a flat surface covered in deep scratches, and they show through paint.
The questions welders ask
How do I avoid burning stainless with a flap disc?
Lower the speed and lighten the pressure. Stainless conducts heat poorly, so it discolours in seconds under a fast disc. A grinder with speed control run at 5,000 to 7,000 rpm, moving continuously, keeps the surface cool enough to stay bright.
Last reviewed 2026-08-14