Finishing techniques give your work that final professional look, so they’re worth paying attention to. 3D printing with a filament extruder is a process that leaves a lot of room for improvement in the surface finish of the parts. Most hobby-grade printers leave very visible patterns from the extrusion that are sometimes attractive and other times just seem to detract from the overall appearance of the part. It’s hard to get rid of them entirely, but there are some techniques available that help. One of the easiest is to polish your ABS parts with Acetone vapor. This is a very cheap and easy technique that anyone working with 3D Printed ABS plastic should try.
First thing you need is a heated chamber to contain your part and vaporize the Acetone. There’s a piece of cookware called a “Presto Kitchen Kettle Multi-Cooker Steamer”. It’s just a cheap and cheerful little self-heated pot that includes an electrical thermometer control, a tempered glass lid, and a drop in basket. Perfect for our task and cheap. I ordered mine from Amazon for $40, but they can be had cheaper if you head out to your local discount store. In addition, you’ll need a small container of Acetone. Acetone is commonly used as fingernail polish remover and is also used as a solvent. I got mine from the paint department of the local hardware store. Here are the basics:
The fabulous Presto Kitchen Kettle Multi-Cooker Steamer and accessories…
You’ll note some gold colored tape in the bottom of the basket. That’s Kapton tape that I applied so my parts wouldn’t pick up round indents from the holes in the basket. I suppose you could also drop a circle of glass into the bottom for the same purpose.
Note that I have arrayed the components for my Acetone Polishing experiments outside on our BBQ counter. Acetone fumes are noxious and the stuff is flammable, so do yourself a favor, be safe, and do your polishing outdoors.
The other modification I want to mention is adding some crude feet to the basket to raise it above the level of the liquid acetone:
The basket needs “feet”…
I just used some socket head cap screws I had laying around and double nutted them in place.
Now you’re ready to go. The process is pretty simple. Put a small amount of Acetone in the bottom of the chamber. Just enough to cover the bottom will be plenty. Put your basket in with the part and cover with the glass lid. Now turn up the temperature controller until the light just turns on. You don’t have to get Acetone very hot before it vaporizes. Pretty soon you’ll see the vapors condensing on the glass lid and dripping back down via the sides. Having a domed glass lid is perfect for this. As soon as you see this happening, shut off the temperature controller. Now you need to decide how long to polish for. It doesn’t actually take very long at all. I did a couple of runs and found that leaving the part in for 1 minute after the initial minute of warm up was about perfect. You can leave it in longer, but there comes a point of diminishing returns. I was determined to see where that was and managed to destroy a part at the 25 minute mark:
Overcooked this one in Acetone: 25 minutes…
As you can see the plastic started bubbling up in a fine froth in a number of places. The polish really wasn’t a lot better than the 2 minute part even though it was cooked a LOT longer, so there’s not much value in getting too carried away with it. One thing about the overcooked part was the heat was left on the whole time. Based on some other articles I saw, it seems likely that liquid acetone got on the part and boiled and that’s what led to the froth. Some of the references at the bottom were able to go a lot longer by carefully controlling the process and avoiding too much heat.
As for the part that was done for less time, it was this one:
1 minute of heated acetone, turn power off, wait 1 minute more, open it up and let the vapors disperse…
One thing that’s immediately apparent is the Acetone makes the parts extremely glossy. Something that is perhaps a disappointment is that the “grain” left by the extrusion was not erased. I have seen parts that look fairly well melted that did a better job getting rid of the grain. They used a different process of some sort to get there. Others seem to get rid of the layer lines without looking melted. Some experimentation is called for to find the optimum results. I have not yet perfected my formula for it, and will be trying more experiments as I get more parts off the 3D printer. For now, take a look at the links below for more ideas on how to do Acetone Polishing of ABS plastic.
More Ideas for Acetone Polishing
Here’s a bibliography of articles on Acetone polishing that may give you some more ideas on how to refine the process for your own parts:
Slick Trick Adds Much-Needed Shine to 3D Printed Parts: This one uses the heated bed of the 3D printer and a jar to do the acetone polishing. Temps were 90C. They get that almost melted look. Not sure I really like it. Seems like you lose too much detail, but maybe that look is what you want to go for.
DIY Smoothing Station: This one focuses on using the Presto, like mine. He also freezes the lid to promote vapor condensation.
Presto Part Finisher: Another one based on the Presto. I probably followed this guy’s recipe the most closely.
3D Printing Tip of the Week: Cheap Acetone Vapor Part Finisher: Another Presto article. He was able to leave his parts in the container for 1-2 hours to achieve maximum results. I’ll definitely try again to cook longer. I think it’s all about the temperature control.
7 steps to shiny porcelain finish on ABS parts with acetone: No heating is used at all. Rather, the parts are placed under a metal can and the acetone is on paper towels held to the top of the can by magnets. 40 minutes later you get the porcelain finish. The parts certainly do look good here!
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