Study in ABS Surface Finish (Q55101)

Attached are some photos showing the results of a simple experiment with printed ABS surface finishes, specifically "washing" with acetone (nail polish remover). The first picture, "ABS Unwashed.jpg", is the print (Yoda Lite) with no treatment done to it. As expected, the finish shows the layers clearly and has a slightly rough finish to it. The second, "ABS Acetone.jpg", shows the finish after a quick (~10 second) bath in acetone. The part was immersed in a metal dish with the acetone and removed, allowed to air dry. The finish is much smoother and hides the layers partially. Interestingly, it has a distinctive "wet" look to it. (For some time, I thought the acetone wasn't drying, but in fact, it just looks wet.) It also feels really nice and clean. In the third picture, "ABS Acetone water.jpg", I rinsed the acetone off with water immediately after the bath. This left a distinctive white discoloration and "taring" of the finish. It looks like paper towel shreds were left on it. In the fourth, "ABS Gradient.jpg", I tried to create a "gradient" of time in which the surface was immersed. The right-most side was about 10 seconds, and the left-most had none. This is the bottom of the model which has the grid lines from the raft. You can see the transition from virtually no grid-marks (right) to fully marked (left). Since the model is hollow, after the bath, the bottom surface is noticeably weaker; with a little pressure you can depress the surface. This is not the case with the unwashed model, so even this small amount of dissolving has changed the mechanical strength of the model. I have concluded that in some cases, it is certainly worthwhile to give the printed model a quick acetone bath. This gives a more polished look. I would also consider using acetone if some parts were a tight "fit" and I needed to dissolve a very small amount of material (much cleaner than a knife, file, or even sanding). Finally, let the parts air dry; do not use water to rinse them. I'd love to hear other people's comments on surface finishing!