How to Smooth ABS 3D Prints | Vapor Smoothing Step by Step

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Martin has a M.Sc. in physics and has gained many years of experience in industry as a lab manager and quality assurance manager. He has now tested dozens of 3D printers and is happy to share the collected experience with each new article.

ABS

Before we can talk about methods for smoothing, we must of course clarify what material we are talking about in the first place. The abbreviation ABS stands for “Acrylonitrile butadiene styrene”.

It is an industrial plastic that makes up the second most common printing material in 3D – behind PLA.

Although ABS is often quite tricky to work with, it has the great advantage that it can still be smoothed with acetone after 3D printing. This is comparable to post-production in the film industry – a lot can still be done!

Acetone

Acetone represents a colorless solvent that is actually mainly used for cleaning purposes.

Probably the best-known acetone product is nail polish remover.

In 3D printing, however, it has now found a new field of application. The advantage: ABS is enormously reactive to acetone and dissolves in it.

This effect can be utilized in steam smoothing, but also in other methods around smoothing ABS 3D prints.

The process completely and totally removes all visible layer lines, resulting in a smooth and clean surface. The 3D printed part then looks more like an injection molded object, not like it just came out of a 3D printer.

Acetone, by the way, can be purchased at a local hardware store. Alternatively, drugstores often offer the solvent, but not all.

Here* you can find acetone at Amazon – often times the easiest and cheapest way to get high-quality Acton.

Smoothing ABS 3D Prints

Creativity and the spirit of discovery play an overriding role in 3D printing. The industry is characterized by increasingly modern technologies and constant change. It is not surprising that there are also several options for smoothing ABS 3D prints that have developed over the years.

One of them, however, stands out.

Method #1: Apply Acetone with a Brush

There are a lot of different ways to apply solvent to a material. The simplest is to apply the acetone to the 3D print with a brush – after all, you only need acetone and a brush.

The problem is that a large proportion of the acetone is usually used up, and the desired effect is rarely achieved – the surface can never be as smooth and glossy as it is with a steam bath with acetone.

There is also a risk of white spots appearing and remaining on the surface.

Method #2: Acetone Bath

Another option is to immerse the 3D print in an acetone bath.

However, this variant is also not recommended – especially for beginners. After all, there may be various problems that arise when handling the object.

Firstly, the project is normally touched when it is removed from the bath. This can damage the surface.

What’s more, the solvent can escape inside the model, causing even more damage. Last but not least, it is enormously difficult to estimate the ideal immersion time.

If the object is bathed for too long, it will be contaminated by dissolved plastic. Objects which are to be smoothed in a bath of acetone often twist strongly.

In some cases, it is possible to quickly dip an object in acetone to get a polished surface. However, it can just be very messy and not give consistent results.

Method #3: Acetone Steam Bath / Vapor Smoothing

When smoothing ABS 3D prints, one option stands above all others: By far the best way to smooth a 3D print is to expose it to the fumes of the solvent.

The steam picks up the advantages of an acetone bath and at the same time does not have the same disadvantages. ABS acetone steam smoothing is relatively easy to perform, but some factors must also be taken into account.

The keyword here is control because you have a lot more of that here than with an acetone bath. Since the vapors can reach all exposed surfaces equally, there are fewer areas that are melted unevenly.

There are also no drainage channels or drip marks on the surface of the object, which in turn can be caused by direct contact with acetone liquid.

How Does Smoothing Work?

The basic principle of smoothing is that the surfaces of the respective ABS 3D print are melted.

However, this should only be the case to a very specific point: The surface tension of the molten plastic should compensate for any irregularities on the surfaces. It is precisely at this point that the process should be stopped before structural damage occurs.

Smoothing is therefore a process that requires a lot of sensitivity and also experience. With each attempt, the ABS 3D prints will become better and more extraordinary.

With the factors of time, patience and action, the ideal combination must be found over several attempts.

ABS Vapor Smoothing with Acetone Steam Bath

Steam smoothing with acetone is generally the most popular and also apparently the best way to smooth ABS 3D prints and give them the desired design.

From a technical point of view, the process is easy and fast. However, it can take a while to reach perfection. Below, we have summarized the process and also packed important tips in the guide.

What You Need for Vapor Smoothing

Before getting started, there is obviously the question of what is needed for steam smoothing with acetone. Below is a brief checklist of what is needed:

Acetone (so far, so clear)
An ABS 3D print (you guessed it)
Metal container or glass container
A whole load of tissues
Magnets or clamps
Aluminum foil
Timer
Safety tips

Safety First

And one more thing before you get started: Safety first – and therefore some safety rules should be followed.

The first thing you should definitely learn about is acetone (propan-2-one). How is it used and what effect can it have?

It is the responsibility of each person to be familiar with the solvents they use.

First, you’ll need high-quality acetone to get consistent results (e.g. this one on Amazon* – I’ve had good experiences with it).

After researching, you are then ready for steam smoothing ABS 3D prints if the following points are considered:

It is essential that the room is well ventilated.
Acetone is extremely volatile and the vapors are also highly flammable. Therefore: No naked and unprotected ignition sources, no flames or fireplaces, etc.!
The acetone must not be heated under any circumstances. The reason should be clear.
Inhalation of the vapors over a longer period of time should be prevented in any case. A mask is useful.
Skin contact with acetone is also a no-go.
When steam or vapor smoothing, make sure that neither children nor animals are in the same room.
Do not pour liquids onto surfaces. The reason: There are a lot of surfaces that can be damaged by liquid acetone – this includes almost all common household plastics.

Step 1: Placing the Object

So now you can finally get started! However, steam smoothing should be carried out with a clear plan, a structure and four steps that are worked through one after the other.

The first thing to consider is how the ABS 3D print – our object to be smoothed – will be oriented. After all, the surface should be where it is needed.

It never hurts to place the object on its base first. However, it is also possible to place it on a side, which does not need to have a smooth surface finish.

The base of the object is finally placed on the aluminum foil, which should be folded three or four times beforehand. Alternatively, surfaces made of glass or metal can be used as a base.

Then the tissues come into play. They are soaked with acetone and placed on the walls of the glass or metal container used. A magnet can be used so that the tissues really stick.

Step 1 is completed by placing the container upside down over the ABS 3D print.

Very important: The tissues should not touch the object!

Step 2: Wait

This is a very relaxed step, because nothing really needs to be done here. The second step requires patience. Just sit back and watch – and set a timer for 15 minutes.

With each minute, the ABS 3D print becomes a bit shinier. After 15 minutes, the container can then be taken down again.

If you have a little experience and see that it can be made even shinier, you can wait for a little longer after the 15 minutes have passed – under strict observation, of course.

The reason: it is quite possible to overdo it with the steam bath.

After all, with time, 3D printing could lose just about all surface details. 15 minutes is therefore a good start. Over time, you’ll know how long different objects need to sit in the steam path.

Those who have performed the steam bath a few times should quickly discover differences and can accordingly adjust the time to achieve the desired result.

Once the container has been removed, the object should first be left alone for a while.

Step 3: Remove Object & Curing

If the container has been removed, then the ABS 3D print should not be touched under any circumstances. This way, the surface could be permanently destroyed and the whole project could fall into the water.

The reason for this is that shortly after the steam bath, the object is still in a deformed state, which only solidifies with time.

If you don’t want your own fingerprints to be immortalized, don’t touch it!

This motto applies for at least one hour, which is how long the object should rest without being touched. During this time, the ABS 3D print should be in an isolated room.

In the course of an hour, all the acetone should have evaporated from the surface of the object, if it was bathed for more than 15 minutes, then it should also rest for more than an hour.

In this hour it can be quite interesting to observe the object in its change. It looks shinier and thus more finished with each passing minute.

So here again patience is needed, only when the magic of acetone has ensured that the object looks absolutely finished, then it can be touched.

Step 4: Examine the Result

So there it is, an acetone-smoothed ABS 3D print that almost doesn’t look like a 3D print anymore. Anyone who tries the steam bath will be amazed at the result, that much is almost certain. Over time, you can see that each object gets even a little bit better.

Tips & Tricks – ABS/Acetone Vapor Smoothing

In order to make the steam smoothing of an ABS 3D print work even better, we have summarized some more tips and tricks below, which might simplify the process.

Finding the Right Container

Glass is very suitable for the steam bath, but it is often not easy to find a glass bell with the right dimensions.

There are some decorative glass bells on Amazon* that are perfect for this.

Alternatively, a metal box can give a similarly good effect, but the same problem exists. If a steam bath is often used with an ABS 3D print, then it may be worth purchasing a smoothing station.

This can be a Polymaker Polysher, for example. The devices work at low temperatures and distribute the solvent evenly, which results in a beautiful gloss. The device is now available in various stores, such as Amazon* and 3DJake*.

Fan Increases Effectiveness

A nice feature for the container is a fan.

This is certainly not a must, but it can increase the effectiveness by improving air circulation. The fan should be attached to the underside of the lid so that the airflow is directly directed at the respective model.

Heating Pad Accelerates the Process

And one more optional feature, which can prove to be helpful. A heating pad will better saturate the air inside, speeding up the entire process.

Alternatively, the container can also be placed on a warm surface – but this must not be hot under any circumstances! Only warm.

Metal Plate as an Ideal Base

The base is an important factor in the steam bath. The ABS 3D print must have a good base and it can find it through a metal plate, which can be placed on cardboard.

It is important that it has a few centimeters from the surface. As a basis for smoothed models, an old printer steel sheet is very suitable. So you can work well without touching the model.

Conclusion

Smoothing ABS 3D prints is extremely useful and can result in an impressive effect.

Some of the smoothed models hardly look like they really came out of a 3D printer anymore. Such smoothing is all the more attractive when you realize that it is quite easy to do.

Acetone* is almost ideal as a solvent. However, there are different methods of proceeding with the agent. The use of a brush is obvious, but not particularly promising.

An acetone bath is more suitable, but it also has some weaknesses. Vapor smoothing with a steam bath is the best method for smoothing an ABS 3D print, as it is a simple process that can have a great effect.

Before vapor smoothing through a steam bath should gather all the necessary utensils and follow safety guidelines.

The greatest danger is that acetone is highly flammable. When everything is ready, then you can start the process, which requires, above all, a little patience. Enthusiasm also can not hurt.

The result is a completely smooth object that really shines. By optimizing the process, progress can be made quickly if the shine is still somewhat weak at first.

If you’ve taken a liking to the steam bath, you can make your life even easier by getting better equipment – but that comes at a price*.

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