I have printed in both ABS and PLA so far. My printer isn’t top of the line or anything close to that cause I’m broke. So when my prints finish, there can be some ugly spots that need sanding. When I sand them down, the plastic becomes grayer. If I run water over it, the problem is fixed but only temporarily as the plastic begins to gray again as it dries. I sand it down by starting with 60-120 grain sandpaper (I use these grains frequently so I start with my lowest I have available at the time.) and work my way up to 1800 grain. Any advice or explanation would be much appreciated! http://ift.tt/2l5UUWY