Removing support structures and rafts will cause white marks/spots and areas. There are 2 fast and easy methods to restore the color back to its original ABS colour.
Method 1: Use a lighter (Best Method) 1. Just a heat from the flame will do, move the flame lightly around the area.
Note: Do not expose too much heat on the ABS, may leave black mark. Expose heat too long will melt and burn the ABS. Tips: You can use a hot gun if you have one.
Method 2: Acetone 1. Lightly brush a thin layer of acetone over the spot 2. Repeat the process if require.
Note: Too much acetone will melt the ABS. Do this in a ventilated area, acetone and ABS are fuel ingredient for fire.
Watch my other video on ABS warping solution: http://youtu.be/HoPGaZCrrJ0