I’ve been using smooth with relax enabled and it works ok. It still alters the geometry a little though…noticeable only up close.
I tried the smudge tool but that does something entirely different.
Smooth tool and set the intensity to 0.
Ah, ok.
I’ve been changing the slider up and down thinking it controlled blur intensity 
I guess my follow up question: How can I adjust the blur strength?
Thanks!
Intensity slider in the painting/material menu.