So, it's up to you. The buffer with the black stripping pads will work well so long as you go over it well a few times. You could use T.S.P. (tri-sodium-phosphate (phosphate free of course)) and water with the scrubber and the rinse really well a couple of times and that should do it. Though acid etching is also a fine option and may be a bit less work while opening the pores up a bit better.