Acetone Vapor Bathing ABS Parts

Scientific method

Question

• What is the best way to use acetone to process ABS printed parts?

Research

• Acetone is a solvent for ABS and makes it pliable. Bathing parts in acetone vapor will soften them.

Hypothesis

• The more acetone in a chamber will produce faster results but in small amounts there will be a limit to the softening.

Test

• Video evidence showed the results of the tests.

Analyze

• The first part of the hypothesis was wrong, having large amounts of acetone in a chamber didn’t result in softer parts, the acetone had to be diffused. The second part of the hypothesis was correct, a small amount of acetone, readily diffused, would soften parts a given amount then stop.

Report

• Paper towels provide a repeatable and disposable diffuser well-suited to acetone vapor bathing. Small amounts of acetone will process parts to set softness then stop. High amounts of acetone will process parts quickly but the process must be halted to avoid over processing the parts.

It is advisable to use a flat bottom in the chamber so parts do not take the shape of an irregular container.

Step 1: Equipment and Explanation of Steps

Five experiments were run to determine the effects of acetone on ABS prints. These were all scraps of a failed batch with particularly rough surfaces, perfect for acetone smoothing.

Equipment was simply

• a glass bowl. I used a one quart bowl
• a glass plate
• two neodymium magnets coated in nickel
• acetone
• paper towels

For demonstration purposes an LED light was used to keep heat to a minimum.

I mentioned that the magnets were coated in nickel, this is what neodymium magnets are usually coated in so if they are the inexpensive off-the-shelf rare earth magnets you have the correct ones. Don't use rubber coated ones.

This experiment was performed in a well-ventilated room. Be sure to follow all safety guidelines on your acetone.

Step 2: Control Experiment

The first experiment was the control experiment. No acetone was used. No video recording was made because this was a time to establish a repeatable method. Time-lapse photos were taken but the result was too large so changes were made. An explanation of this can be found on the blog but the result was that nothing happened. As expected.

Step 3: 4 Inch Square Test Results

A small section of paper towel was cut, 2" by 2". Using paper towel area, as opposed to volume, makes measuring easy for anyone else who wants to repeat this experiment. The paper towel was soaked in acetone and allowed to fully saturate. Acetone won't dissolve paper the same as water so the paper towel won't soften as it would when dampened with water. Magnets were used to hold the paper towel to the top of the chamber, one magnet outside the chamber and the other touching the paper towels.

Time-lapse video was taken to show the acetone working on the plastic. Unfortunately a lens was not used to magnify the plastic while it processed so it's not clear what happened or how fast. However the end result shows that the rough surface had become shiny after processing overnight.

This technique is great to get a little bit of a shine without having to worry about a timer. Just pop the plastic in the vapor chamber with four square inches of acetone soaked paper towel and let it sit overnight.

Step 4: 8 Inch Square Test Results

For the third experiment eight square inches, 2" by 4", of paper towel were soaked in acetone. This doubled the acetone from the last experiment. Additionally, a lens was added so the experiment could be seen better.

Most of the processing happens in the first two hours which can be easily seen in the video. The effects were more dramatic than before but the pieces should be taken out after two hours so they aren't damaged. Fifteen minutes more or less won't hurt the print.

This technique is great for taking the rough spots off your print and adding a shiny finish but it should be timed.

Step 5: 16 Inch Square Test Results

Sixteen square inches of paper towel material were soaked with acetone and processed with the plastic parts. Time-lapse video showed the plastic softening then becoming weak with the high concentration of acetone. After processing the plastic piece wouldn't come off the glass plate because it was "soggy." There is video on the blog showing how pliable the piece was. After being removed from the acetone vapors for a few hours the plastic was back to the same hardness as before.

This technique will produce a very smooth surface but it must be removed from the acetone in less than two hours. Do not handle the pieces for eight hours or they may be damaged.

Step 6: Open Container Test Results

The last experiment used a shot glass filled with acetone which was set inside the chamber. Oddly, no effects could be seen on the printed pieces. Perhaps the acetone vapors were too heavy to leave the shot glass.

This technique does not work.

Step 7: Results and Conclusion

For an easy to follow recipe use four square inches of paper towel soaked in acetone. Let it process overnight and don't sweat the details.

if you need quick results douse 16 square inches of paper towel in acetone but stop after two hours.

A plate with a flat bottom is best. As the parts soften they can take the shape of the container. Any glass will work, even a mirror with no frame.

Step 8: About Me

Thank you for reading this Instructable. If you like it check out my site where I blog incessantly about my projects. There is a day-by-day write up of this project including videos not shown here and I explain the reason I didn't post a video of the control experiment.

I have lots of 3D printed projects and lots of projects which don't use a 3D printer.

Comments

[Wolfbane221]

if you have two airtight chambers one with the parts and one with acetone, you can vaporize the acetone by pressurizing it. at least that's the basic concept.

[24Eng]

Do you mean like a spray mist?

[Wolfbane221]

not a mist that you spray, more like a cloud in a bottle. and I was wrong about it being pressurized, my bad.. hadn't seen the instructable in a while. have a look! https://m.instructables.com/id/Ultrasonic-Misting-3D-Printing-Vapor-Polisher/

[24Eng]

That looks like it would work crazy fast. dchesson93 suggested adding heat. I imagine the combination of these two methods could process lots of parts really fast.

[Wolfbane221]

true, however heat can warp parts due to temperature differences. I once used a heat gun to try to join two parts and the part just curled up. I think with a temperature controller it might work but honestly the acetone bath should be plenty plus, I'd rather not mix heat with flammable vapors. even if controlled

[24Eng]

Ha, I tried to use a heat gun to melt thin parts into a t-shirt. I was looking for simple way to make printed t-shirts but I had the same problem where the parts curled up. I even pinned them under paper.

I wonder if I could have sprayed them with acetone and let them fuse with the shirt when they softened. This has gotten my brain going.

If you want to join parts consider one of those 3D printing pens like a 3Doodler. They are great for plastic part joining.

[Wolfbane221]

I've got a 3d doodler actually, and tried to do that the other day. unfortunately I lost the DC power supply for it and am not sure the output I need. I grabbed one from an old linksys router but it wasn't powerful enough to make the extruder work. if you have one can you tell me the right output I need to find??

[24Eng]

The Kickstarter model used a 12V 2A positive tip power converter.

[dchesson93]

I work in a lab where I have access to a fume hood and various heating elements. I've found a good way to get a fast, effective polish is to find a tall container (I've used a 2 l. beaker with good results), add a very small amount of acetone, vaporize it on a hot plate, and lower the part into the vapor very, very briefly (I've constructed a crude metal cage much like the ones in deep fryers to accomplish this), and pull back out. Allow the part to re-solidify.

Again, this was done under a well ventilated fume hood. Don't go trying this on your stove at home. A well ventilated, outdoor area should be fine, I think. Rule of thumb: if you aren't sure you should be doing it, don't.

[24Eng]

Very nice. How long do you hold it in the vapors?

[dchesson93]

Not long at all. Depending on part size and desired level of polishing, I'd say a minute or two (at the extreme end). The temperature makes a much more concentrated vapor cloud than you'd get with the paper towel, which can be both a good and bad thing. It polishes (or ruins) parts very quickly, so I typically dunk fit for 20-30 seconds at a time to make sure I don't over do it.

If you're interested in this method, I have another tip to save you some time and parts: for flat-faced parts (in my case, it was a beaker cover for a plating bath I was working with), you'll get the best results if you flip it over halfway through. Otherwise one face will be heavily polished, and the other will be relatively untouched. I'd assume this could be applied to your method, too. On the flip side, I used this method on a small model person with pretty good results without flipping. I'd say this is due to the curved surfaces on the person.

[24Eng]

If someone just had regular household appliances and kitchen equipment could they do something similar? I like the idea of a two minute soak time.

[dchesson93]

Absolutely! I had a buddy who made his out of a fryer or crockpot, can't remember which. You could make a pretty neat setup with fryer, now that I think of it. Any semi-deep, steep sided container with a heating element capable of vaporizing the acetone would do, but a fryer would come with that metal cage I mentioned earlier that makes lowering the part into the vapor a piece of cake.

Two things to emphasize, now that I'm thinking. First, I was able to use something like a soda bottle cap worth of acetone to polish one medium sized print. You'll have to play around with your amounts for your setup, but that gives you a ballpark amount for reference. The acetone vapor can be seen (barely), actually, so deciding whether you have the right amount is essentially just assessing whether the acetone vapor is deep enough to dunk your part. Second, I know it's common sense, but it's not a great idea to do this in a non-ventilated area. Breathing acetone vapors is not a good idea, so I'd be very careful about where I did this.

Let me know if you make a standalone system. For some reason it hasn't ever occurred to me to do that! It's going on the project lists right behind building my own printer!

[24Eng]

We should also mention to any kitchen DIYers that a flame heat source is a bad idea. The acetone bottle will confirm.

Thanks for the suggestions and good luck with your printer!

[dchesson93]

An excellent point! Nobody needs to go burning their eyebrows off. Thanks for the cool Instructable! Always love seeing additive manufacturing stuff on here.

[24Eng]

Be sure to take notes and pictures when you build your own printer and acetone chamber. I can't wait to see it.