Here is a piece (not modelled) not sanded at all, half dipped in acetone for 25secs and then sprayed with undercoat primer, and then with gold paint. I think it illustrates how nicely acetone smooths Ultimaker Blue PLA, shame it is apparently no longer available. I still have a bit thank god, and some green which also appears unavailable. I wonder if the new UM BLue available is just as good chemically to react to acetone as the old one that came with the printer. If not thats a VERY big shame.
Just thought i would post this in case people wonder how the surface of PLA can easily be smoothed whilst still keeping most detail unlike ABS. A step that is essential if you plan on painting your creations and do not want the model covered in distracting print lines.
You can do this with color-fabb PLA as well but it takes longer and does not wipe as many lines away.