Dalemilam

I recently acquired a nice bunch of mostly Veg Tanned leather...some of the rolls have what I assume to be mold or mildew in s few spots...is there any thing I can use to remove this without damaging the leather...I figured I would try and brush as much as I can with a brush that won't leave any marks, but after that I'm not sure what I can clean the rest of it off with...Thanks in advance...