Introduction: Safe Way to Do Acetone Bath

Picture of Safe Way to Do Acetone Bath

Acetone bath is a great way to make your 3D-printed models look awesome. However, since we are dealing with acetone vapours the whole process is quite dangerous to perform.

This is the fastest and the safest way to do acetone bath that I have developed so far. You will need common household tools and items. It is the safest way I know but still don't forget to open windows and don't use open fire! Or you will experience a HUGE fireball.

Acetone vapour is probably the best medium to polish/smoothen 3D-printed models. Acetone boils at 56°C/133F. We need to hold it in slightly higher temperature to make it boil slowly and continuously. The temperature needs to be not too low but not too high either.

Water seems to be a perfect medium for this purpouse. It can hold temperature from 56 to 100°C/133 to 212F quite a long time.

So the principle is:

  1. Pour acetone in the inner pot
  2. Put model in the inner pot above acetone level
  3. Pour boiling water in the outer pot
  4. Wait a while. It should not take more than one minute
  5. Take the model out.

Acetone will only work with ABS or PET items. If you are using PLA or Nylon you will need some other solvent.

Step 1: Prepare the Items You Will Need

Picture of Prepare the Items You Will Need

  1. A pot and a cage that fits inside it.
  2. Kettle
  3. Another larger pot. We will put the first pot inside it. Let's call them inner pot and outer pot.
  4. Acetone

Step 2: Boil Some Water

Picture of Boil Some Water

Pour about 0.5 liter of water in the kettle and make it boil.

Step 3: Prepare Acetone

Picture of Prepare Acetone

Meanwhile put inner pot in the outer pot and pour some acetone in the inner pot. About 0.5 deciliter should be enough. The larger the model the more acetone you will need. The model must not touch acetone level!

Step 4: Prepare Your Model

Picture of Prepare Your Model

  1. Put your model in the cage.
  2. You can put aluminium foil on the bottom to prevent the model to merge with the cage while it is being etched by the vapours.
  3. Put the cage in the inner pot with acetone.
  4. Cover the pot.

Step 5: Make It Boil!

Picture of Make It Boil!
Pour boiling water in the outer pot. You should immediately hear acetone boiling. Model should start to look wet and you should see the edges are more and more smooth. Don't let the model in the vapours for too long or bubbles will start growing on the surface of the model. When you see the model is smooth enough, get it out with the cage.
Don't freak out when you put your hand inside the inner pot. The vapours inside are hot but not dangerous and it is a very strange feeling.
This step should not take more than 1 minute.

Step 6: Dry Up

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Now we want the model to dry up. Put the cage with the model outside and wait about 10 minutes.

Step 7: That's It

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Model is now smooth and shining. Since I know this method I am not printing at .1mm resolution any more. I am only using .3mm layer height and then I boil it in acetone vapours. The final result is the same but printing process is much faster.

As you can see, large holes are still not smoothened properly. You will need to use some other technique to make them look nicer.


Legerstee1 (author)2017-09-03

Thank you so much for this howto. Since this is more than two years ago have you improved your process? And is adding a fan a good idea?

PeterA8 (author)Legerstee12017-09-03

I am still using the same equipment. Still the same process. But there was an instructable somewhere, where a cheap ultrasound device was used to make the vapours.

Legerstee1 (author)PeterA82017-09-04


UncleTiki (author)2015-04-19

did you print with abs or pla?

PeterA8 (author)UncleTiki2015-04-19

ABS. Acetone is good for ABS or PET. PLA is very resistant to organic solvents.

trevoratkinson (author)PeterA82016-12-09

the best solvent for PLA is dichloromethane is also effective on ABS

KyleG44 (author)PeterA82016-02-21

From what I've read PLA is soluable in ethyl acetate (which is marketed as an M.E.K. substitute in states where it's not prohibited to be sold to individuals.) Regardless the synthesis for it shouldn't be terribly expensive or difficult if someone had a bit of organic chemistry equipment and a proper education and background to use it safely and within the confines of the law.

Make it BIG (author)PeterA82015-04-22

Maybe you should add that in the Instructable, so people don't try it with their PLA prints and are disappointed afterwards.

jellmeister (author)2015-04-24

Nice, though I'm not sure I'd call it safe. Explosive atmospheres are not something many people understand, and I think your fireball warning should be a bit bigger. Even static discharge could give a really dangerous explosion and life altering injuries. There tends to be a feeling in the population that only a small amount means how bad could it be, but it you evaporate it into a really good air-fuel mix it will explode worse than a cup full of petrol. Be careful, avoid flames or embers, avoid plastics and nylon, and do it outside!
Sure most people get away with it, so it can't be that bad, but understand the risks everyone, the vapours aren't top of you worries!

Nikon1Team (author)jellmeister2015-04-28

I work with acrylic resin, cast pens. There are warnings on the acrylic resin cans. Anyone on here work with these acrylic materials? I'm considering putting an in-line inductor fan in a 4 inch duct; one end with be through the shop wall....the inside end of the duct will be into a plywood "de-gassing box" that will hopefully confine the fumes. I intend to incorporate vents into the box, to regulate the "inflow" air, thinking that it would thus decrease the concentration (smaller fuel-to-air ratio) of the volatile gasses. Anyone have any residential shop experience or thoughts with using this type of degassing chamber?

Stephen Dodd (author)Nikon1Team2015-05-06

Many flammable liquids do not become explosive until a particular mixture with oxygen is achieved. Indeed if the mixture is too rich it may be unlikely to ignite. Of course the bad news is that one may think it is safe becasue it hasn't gone off yet. Once it does become dilute enough the explosive tendency emerges. So sucking fumes off an industrial operation could be just the situation where explosive mixtures may sometimes occur.

Stephen Dodd (author)2015-04-23

Acetone is well known in the chemical industry to be a ketone which is absorbed by the skin and devastates the liver. I would not go near it without full technical procedures for protection.

If acetone were particularly deadly, the population balance would favor men as many women would have met an early end from fingernail polish remover, the chief active component of most brands being acetone, and the use of which inevitably involves direct application to skin. But to each one's own, and there's no harm being extra cautious.

amclaussen (author)barry_johnson2015-05-05

Bad example: all nail polish removers I know are NOT pure acetone, but DILUTED acetone, and the second ingredient is usually some kind of cosmetic, harmless oil (like lanolin or sheep's wool oil) in order to "moisturize" the skin. That second ingredient protects the skin and lessens acetone absortion into the skin.

Therefore, saying that "acetone" in Nail polish removers would have killed many women is tendentious. Better keep a safe attitude and be careful.

On another risk, explosión of acetone vapors is very real, so it must be used outside, far enough from ignition sources. A pal that flies model airplanes went into model "Diesel" engines that use a different fuel made with Ether, Kerosene and an ignition improver. He was storing the ether inside an old fridge. Somehow one of the glass flasks ruptured and leaked ether, which vaporized and reached the fridge's compressor, which ignited the mixture blowing his garaje with all his model plnes, radios, two cars and almost burned his home entirely!... and acetone is almost as volatile as ether. Amclaussen.

barry_johnson (author)amclaussen2015-05-06

I am not sure you are using the word tendentious as you may intend - it is certainly an inaccurate word choice as it regards my intentional state when writing the comment. You do at least identify what is actually the most common hazard of acetone in terms of its flammability. To any future readers of the comment thread, just hit up your preferred search engine for an MSDS on acetone or just go to the wikipedia page on it where you can read about its further use as a skin peel and further comments on its toxicity.

Stephen Dodd (author)amclaussen2015-05-06

Yes this is all true. But sometimes the more one presses a point the more people wish to rebel and do something anyway. When I was young I worked for a time in a boatyard. There was a group there that built 30 foot fiberglass hulls with a "chipper". I was a steel fabricator. But I often worked on combined welding and fiberglass projects. The job of laying up a new hull was horrible. Even the owners tried to avoid it. This even with a mask and positive air feed hose. And of course any venting system could not employ electrical commutator fans. Acetone is really dangerous. It is also toxic. And of course, fingernails are keratin, which is non-living cells similar to hair. The absorption area would be the tiny root area. This would comprise orders of magnitude less than even a single hand wetted with the stuff. I remained convinced this project should be rethought in light of industry standards and professional toxic chemical advice. I am quite sure my old friend who is a toxicologist for Intel would not allow any process in their plants without full safety certification.

MoTinkerGNome (author)2015-04-24

Hey just a note. Here is the MSDS for Acetone. Safety First and respect your chemicals

Potential Acute Health Effects:

Hazardous in case of skin contact (irritant), of eye contact (irritant), of ingestion, of inhalation. Slightly hazardous in case of
skin contact (permeator).
Potential Chronic Health Effects:
CARCINOGENIC EFFECTS: A4 (Not classifiable for human or animal.) by ACGIH. MUTAGENIC EFFECTS: Not available.
TERATOGENIC EFFECTS: Not available. DEVELOPMENTAL TOXICITY: Classified Reproductive system/toxin/female,
Reproductive system/toxin/male [SUSPECTED]. The substance is toxic to central nervous system (CNS). The substance may
be toxic to kidneys, the reproductive system, liver, skin. Repeated or prolonged exposure to the substance can produce target
organs damage

bpark1000 (author)2015-04-23

Do the whole process outside! That way, if something bad happens, there will be less likelihood of disaster.

What about just dipping the part (tied to a string) into liquid acetone for a short time , removing, and drying?

MV2 (author)2015-04-23

You should check OSHA and NIH, acetone is not the most dangerous solvent to use. Your body produces acetone every second during Ketogenesis. Sure the vapors could kill you, but you would need to be in a confined space.

zkus (author)2015-04-23

Good write up. Though I suggest investing in a steamer, which for something like $20 can really streamline things. I have one linked in my related article:

PeterA8 (author)zkus2015-04-23

I also like your method. But I still consider using heat mediator (water) a bit safer than heating acetone directly.

Stephen Dodd (author)2015-04-23

I think the use for fingernail polish does not scale up to production of parts. People who work regularly with acetone used to wash their hands in it, tools, and rub things with rags soaked in it. To them it was a sort of alcohol. But as seen in the MSDS sheet I posted long term industrial use can be dangerous. Chemists as well fear it. In that application it should be used under a sucktiion hood.

starforest (author)2015-04-23

Very helpful.

Stephen Dodd (author)2015-04-23

mjlush (author)2015-04-23

Is the heating really necessary compaired to the cold acetone bath?

Kinnishian (author)mjlush2015-04-23

Heating encourages a more uniform acetone vapor density, it's especially important for tall pieces. It probably won't matter for the thin coin-like piece demo'ed, but maybe for taller pieces.

It also speeds things up. Easier to watch over something when it is not taking as long.

thebeatjackson (author)2015-04-23

I've found Letting the acetone come to the boil, or warm up for a bit before lowering the piece in helps to keep a bit of detail, and about 2 to 10 seconds is usually enough.

mrobinette24 (author)2015-04-21

I use an old rice cooker

mamad3pitch (author)2015-04-21

Thanks a lot for sharing.

It's really helpful for me!

Kafukai (author)2015-04-21

This is one of the coolest things I ever seen in after 3D printing. Awesome, thanks for sharing.

Paulbacca (author)2015-04-21

Nicely done. Thanks for sharing. I assume you have to repeat this for the other side as it is against the foil. Could you hang the item from the side of the cage to the vapours coat the item all over?

PeterA8 (author)Paulbacca2015-04-21

Yes, of course. If it is hangable then you can.

reibuehl (author)2015-04-20

If your 3D printer has a heated printing bed, then you can also use this. I have used this successfully in the past. I prepare the aceton pot, set the heated bed to 60°C and let it warm up. Once it reaches 55°C, I insert the model with a cage the same way you did it. The heated printer bed keeps the temperature very nicely.

PeterA8 (author)reibuehl2015-04-20

I tried it too. But it was taking ages to boil the acetone. This is much faster.

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