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Acetone smoothing 3d printed parts
Acetone vapor baths & other ways to remove layer lines
As a low-cost 3D printing material, ABS is one of the most popular filaments among FDM 3D printer users, beginners and experts alike. Although it has its disadvantages — such as a strong smell when printing and a dependence on heated print beds — it creates durable parts that are resistant to fairly high temperatures.
For many casual 3D printing users, the decision often comes down to PLA, PETG, or ABS filament. PLA has a low melting point and environmental credentials, while PETG is highly impact-resistant. But ABS has one unique advantage over its low-cost competitors: it can be easily dissolved with acetone, which means printed objects can be post-processed to give them an exceptionally smooth surface. While other thermoplastics can be dissolved with other solvents, no combination is quite as effective as acetone on ABS.
That being said, smoothing 3D printed parts made of ABS requires a certain level of skill. Acetone is highly flammable and an irritant to the skin and eyes, so it must be handled with extreme caution. Fortunately, this guide explains exactly how you can safely carry out ABS acetone smoothing, as well as part smoothing via other post-processing methods like sanding and polishing.
One of the major disadvantages of FDM 3D printing is that it produces visible layer lines — ridges on the surface of a part — as a result of moving from one layer to the next along the Z axis. Layer lines are especially pronounced when using a greater layer height (lower Z-axis resolution) and when printing curved parts.
Smoothing your ABS parts is a way to eliminate the appearance of visible layer lines and change the surface texture of the part from matte to glossy. The process is generally carried out for cosmetic reasons, but it can also have functional benefits: smooth, frictionless parts may be required for mechanical reasons or to facilitate the assembly of multiple components.
You should smooth your ABS prints if you want to maximize the aesthetic quality. However, you should exercise caution when smoothing if the part needs to meet strict dimensional tolerances; this is because smoothing takes away a small amount of surface material and consequently alters the dimensions of the part.
Recommended reading: ABS print temperature considerations: Nozzle, bed, enclosure
If you’re looking to eliminate the appearance of layer lines on your ABS parts, your best bet is to invest in some acetone. This section explains how acetone smoothing works and examines four common methods of applying the solvent to printed parts.
Acetone is a solvent found in nail polish remover
How does smoothing with acetone work?
Acrylonitrile butadiene styrene (ABS) is a thermoplastic polymer made by polymerizing styrene and acrylonitrile in the presence of polybutadiene.
As with all polymers, ABS is resistant to certain substances and vulnerable to others.
When it comes to smoothing, the most relevant fact about the chemical makeup of ABS is its solubility in esters, chloroform, ethylene dichloride, and various ketones, of which acetone is one. Substances like chloroform and ethylene dichloride are toxic and require extensive safety precautions, but acetone is milder and much easier to handle in non-controlled environments. It is an active ingredient in nail polish remover, for instance.
So, chemically speaking, why does acetone dissolve ABS? The short answer is that because ABS is soluble in ketones, the presence of acetone causes the ABS (the solute) to dissolve into the acetone (the solvent), forming a sort of soup or slurry (the solution) on the surface of the plastic.
This means that when you apply a small amount of acetone to a 3D printed ABS part, the surface of the part will dissolve. When this is done in a controlled manner, it is possible to dissolve just enough ABS to eliminate imperfections like layer lines, leaving behind a smoother (and fractionally smaller) version of the part.
Some researchers have even suggested that acetone smoothing can improve the strength of ABS parts by increasing interlayer adhesion.[1]
So what is the best way to smooth ABS with acetone? There are different methods for applying acetone to ABS parts in a controlled manner, and we will explore four of them here, noting which ones we recommend and which we don’t.
Safety measures
Acetone is a highly flammable substance that can irritate the skin and eyes, so it must be handled with extreme care. The following safety precautions should be followed with all acetone application methods:
Always store acetone in a cool, well-ventilated area away from direct light, fire, and any other potential ignition sources
Only open your acetone container in a well-ventilated area, wearing a protective mask to avoid inhalation of fumes
It is recommended to wear eye protection and non-nitrile gloves to prevent potential eye and skin irritation
Method 1: Brush application
The simplest way to achieve a fairly smooth finish on ABS parts is to apply liquid acetone to a 3D printed part with a brush.
Deposit a small amount of liquid acetone into a shallow container, then dip the brush into it and apply a very thin coating over the surface of the part.
This method is not highly recommended as it uses a large amount of acetone and produces uneven results: the surface may appear streaked or unevenly smoothed. By applying acetone with a brush, it is also easy to apply too much of the solvent, potentially causing permanent deformation to the part or fully dissolving thin walls.
Method 2: Acetone bath
Another way to achieve a smooth surface finish on ABS parts is to create an acetone bath. This method involves fully submerging the part in a polypropylene (PP) container of liquid acetone for a short period of time, allowing the entire surface of the ABS part to come into contact with the solvent.
This method is not recommended as it requires a very large amount of acetone and can excessively dissolve the ABS part or cause it to warp and twist.
Furthermore, removing the part from the acetone requires one of two difficult procedures: either removing the part from the bath (and therefore touching it, potentially causing surface deformations) or draining the liquid into a container underneath (requiring a more complex, multi-container setup).
Method 3: Acetone vapor smoothing
A much more effective means of ABS smoothing is the creation of an acetone steam bath or vapor bath. This method does not involve the direct application of liquid acetone to the ABS part, but instead allows acetone fumes to slowly penetrate the surface of the part. This can be achieved by keeping the part and the acetone within a container.
This is the most highly recommended method, both for its safety and effectiveness, and we will explain how to do it with step-by-step instructions.
Create a smoothing box
The vapor smoothing method requires a partially enclosed container to keep the acetone fumes close to the printed part and prevent them from escaping into the room (though the container should not be airtight).
For small ABS parts, you could use a glass container such as a glass jar. For larger parts, or to smooth several parts at once, it is better to use a transparent polypropylene (PP) storage container; these are cheap, available in various sizes, and will not dissolve upon contact with the acetone.
A PP container can function as a smoothing box for vapor smoothing
Place a raised platform in the box
Your ABS parts should not touch the bottom of the smoothing box. You will therefore need a small raised platform on which to place your ABS parts. This platform should not be made from a material that is soluble in acetone, or it will dissolve. Metal works best, and a regular plate coated in aluminum foil is one option.
Soak tissue paper in acetone
Instead of pouring liquid acetone directly into the smoothing box, you need only soak some tissue or paper towels in the solvent before adding the paper to the edges of the smoothing box, either by pressing them firmly against the walls of the container or attaching them with magnets (one inside and one outside the box).
Leave at least a small window of uncovered wall surface so you can see the part while it is being smoothed.
Close up the smoothing box
The vapor smoothing will only work if the smoothing box is closed off, as this prevents the acetone fumes from escaping. If you are using a jar or a storage container with a snap-on lid, lay the lid gently on top of the container without sealing it, and make a few small holes in the lid.
It is critical that the smoothing box is not fully sealed, as this can cause a dangerous amount of pressure buildup.
Let the vapor smoothing take place
The ideal amount of vapor smoothing could take between 10 minutes and an hour. We therefore recommend observing the process through the transparent smoothing box, at least until you have an idea of how long you will need for future prints.
Once the desired smoothness has been attained, you can remove the lid from the box and safely dispose of the acetone-soaked paper.
Leave the parts untouched for as long as possible, as their surface will still be soft from the acetone.
Add heat and air circulation (optional)
Once you are comfortable with the basic vapor smoothing process, you can improve its efficacy in two ways: by placing the smoothing box on a warm (not hot) surface or by putting a small fan within the box. However, be careful with electronics, as an errant spark could ignite the acetone and cause a fire.
Method 4: Automated acetone vapor smoothing
A much safer and more consistent method of vapor smoothing can be carried out when using a dedicated post-processing machine such as the Zortrax Apoller. Such machines distribute the solvent fumes evenly while maintaining constant air circulation and gentle heat, resulting in the best possible surface finish and meeting strict safety requirements.
Unfortunately, these machines are much more expensive than the DIY method outlined above.
Also note that the popular Polymaker Polysher device will not work with ABS and acetone, as it is only compatible with the company’s proprietary smoothable filaments and solvents.
Advantages | Disadvantages | |
Brushing | Requires minimal equipment | Uneven application Uses more acetone than necessary Easy to damage printed parts |
Bath | Even application | Uses more acetone than necessary |
Vapor smoothing | Even application | Hard to maintain even smoothing with larger parts |
Auto vapor smoothing | Most even application | Expensive |
Sanding
The most common method for smoothing 3D printed parts, sanding, does not require the use of chemicals.
Sandpaper is applied manually to the part, and its rough surface removes a small amount of material from the part surface.
When sanding ABS parts, start with coarse sandpaper (80-grit, for example), then gradually move to finer grit (120 and 240). Finally, use a very fine-grit sandpaper (1000) with water to make the parts as smooth as possible. Try to apply even coverage right across the surface of the part. Note that while powered sanders can rapidly speed up the sanding process, the heat generated by these machines can adversely affect printed parts. If you have time, we recommend manually sanding ABS parts.
Sanding is safe and easy to do, but it can be difficult to reach deep crevices in the part and to apply an even amount of pressure over the entire surface.
Sandpaper is a safe and simple alternative to acetone smoothing
Polishing
If you don’t want to deal with a strong solvent like acetone, it is possible to create a high-shine finish for your ABS parts by applying a liquid polish (Brasso, for example) with a piece of cloth.
This should be done after sanding, when the surface of the parts is already fairly smooth.
Apply the polish-soaked cloth firmly, making circular motions over the surface of the part until it is fully glossy.
Methods to avoid
Some smoothing methods that work for other thermoplastic filaments won’t work with ABS. For example, isopropyl alcohol (IPA) works just like acetone when printing PVB, but won’t cut through the surface of your ABS parts. Another common smoothing agent is d-lemonene, but this only works for HIPS 3D printed parts. We would also advise against using very strong chemicals like chloroform as a solvent, since acetone is less toxic and just as effective.[2]
Recommended reading: Smoothing PLA 3D prints with sandpaper, solvents, and more
After support removal, smoothing is possibly the most important post-processing technique for FDM 3D printed parts. Smoothing removes unsightly layer lines, giving printed parts the appearance of high-quality injection moldings, and the process can be carried out on a small budget.
Of all common 3D printing materials, ABS is perhaps the best suited to smoothing. Its solubility in acetone provides printer users with an easy route to smooth and glossy parts, making it a highly suitable filament for cosmetic parts such as display prototypes, models, and figurines. In fact, smoothed ABS parts more closely resemble molded or stereolithography parts than as-printed FDM parts.
However, as we have mentioned, acetone smoothing should be carried out with caution. Although less dangerous than other smoothing agents like chloroform, acetone poses risks to human safety, the most significant of which are its flammability and its potential to irritate the skin and eyes. Newcomers to the acetone smoothing process should familiarize themselves with the necessary precautions, investing in a mask and gloves and only carrying out the process in a well-ventilated area.
If these safety precautions are followed, printer users will find acetone smoothing to be a highly effective means of improving the visual quality of their ABS parts.
[1] Gao H, Kaweesa DV, Moore J, Meisel NA. Investigating the impact of acetone vapor smoothing on the strength and elongation of printed ABS parts. Jom. 2017 Mar;69(3):580-5.
[2] Joshi DR, Adhikari N. An overview on common organic solvents and their toxicity. J. Pharm. Res. Int. 2019 Jun;28(3):1-8.
Acetone 3D Print Smoothing: 6 Easy Steps
Estimated reading time: 2 min
Normally, FDM 3D prints show layer lines. Learn about acetone 3D print smoothing and create a totally smooth surface finish in just 6 easy steps.
What Is It?
An acetone-smoothed ABS print. (Source: Alexander Issal / All3DP)One of the many things that fused deposition modeling (FDM) printers lack is the smooth finish you always get from injection-molded parts. Instead, you often get a matte, rough finish with visible layer lines. A popular way to get rid of these layer lines is to sand and fill until the surface is smooth. This method, however, takes ages to get anywhere close to smooth.
Another way that’s not only faster but also much better in preserving accuracy is acetone smoothing, which can be applied to any material that can be dissolved in acetone. The most popular filament to acetone smooth is ABS.
In this article, we’ll take a look at how you can acetone smooth your own prints. Follow along as we show you the process of smoothing the pictured BuddaYoda.
What You’ll Need
Materials for acetone chamber. (Source: Alexander Issal / All3DP)There are countless methods of acetone smoothing your 3D print, some more dangerous than others. We have therefore constructed a simple design with normal household items. Here’s what you’ll need:
- Towels
- One transparent glass vase (a glass jar also works fine)
- Magnets (at least six)
- A plate
- A small clay saucer (any structure that acts as a platform will do)
- Acetone
Optional:
- Aluminum foil
Acetone is a great tool for everything between cleaning your hot end to welding together two 3D printed parts.
However, you need to know that acetone can also be very dangerous if used incorrectly.
Acetone is very flammable, so don’t use it near fire or something that can cause a spark. Also, be sure to work in a well-ventilated area since the vapor can cause headaches, dizziness, and a sore throat if breathed in too much.
Smoothing Steps
Acetone smoothing process. (Source: Alexander Issal / All3DP)Now that you have prepared all of the materials, you can finally start acetone smoothing your prints.
- Fill the plate with water and place the clay saucer on it with the flat side facing up. We have added a layer of aluminum foil on top of it so that the model doesn’t stick and so that we keep that shiny surface from printing on a glass bed.
- Attach the tissues to the inside of your vase with the help of magnets. Then soak the tissues by pouring in small amounts of acetone and rolling the vase until everything is covered.
- Place your 3D printed model on the platform (clay saucer) and slowly lower the upside-down vase over it.
It’s important that the water on the plate makes a seal so that the acetone won’t leak. In the beginning, you will see some bubbles coming out from the water, this is normal and nothing to be afraid of. - Now you just have to wait until the layer lines have disappeared. It can take anywhere from half an hour to a couple of hours. (The Budda Yoda took just under two hours.) If you choose a transparent vase, it’s much easier to see the progress of your smoothing process (where there is no tissue) without guessing or having to remove it.
- When you feel happy with your print, you can carefully remove the vase and remove the print from the platform. Place it on something that doesn’t react to acetone. We recommend using a failed PLA print, preferably the ones that have stopped mid-print and left behind a flat surface with infill acting as an anti-sticking platform.
- The last step is to let your print dry from any acetone leftovers. Sometimes it just takes a day, but it can take many days for it to cure.
When the part has been cured, you now have a 3D printed part that looks like it was injection molded!
Source: https://all3dp.com/2/abs-acetone-smoothing-3d-print-vapor-smoothing/
Tags: 3D printing actone fdm material post-process
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Processing of 3D printed models
One of the problems that all fans of FDM 3D printing, without exception, encounter is the ribbing of external surfaces. Since the technology itself is based on the sequential application of plastic layers, this effect cannot be avoided. You can, of course, make it less noticeable by increasing the vertical resolution of the printer (i.e. applying thinner layers), but you won’t be able to completely get rid of the ribbing.
PLA 3D model before and after torch treatment. The internal structure is visible under the sagging outer layer
Almost from the very first days of the RepRap project, the search began for methods of processing finished models in order to smooth surfaces. Emphasis was placed on two features of thermoplastics: the ability to melt when exposed to high temperatures and soften on contact with the appropriate chemicals.
As a rule, heat treatment does not give good results - it is difficult to control the heating of the surface, and this eventually leads to plastic boiling, sagging or simply releasing toxic fumes. However, this method can be tried on solid PLA models.
Chemical treatment is more promising, but it also comes with its own set of challenges. In addition to technological problems, the problem of reagents is relevant - different plastics react with different solvents. If acetone perfectly dissolves ABS plastic, then it has almost no effect on PLA plastic.
With limonene, everything is exactly the opposite.
The main chemical smoothing techniques still revolve around ABS plastic due to its high popularity and low cost of suitable solvents.
A typical ABS solvent is acetone. Its good dissolving power allows it to be used as an adhesive for component parts of ABS models, although a homemade mixture is usually used for this, produced by dissolving ABS chips in acetone. The same glue (only a thicker consistency) is often used to repair delaminations or cracks.
Along with increased aesthetics, an important factor in the development of smoothing methods is increased strength. The monolithic outer shell reinforces the models, preventing delamination and ensuring their tightness.
Hand shaping
Makeraser - a combination tool designed to also work on the outside of models models. However, processing with a brush is a laborious task, and even requiring a certain skill.
After all, already softened plastic is easy to deform with the brush itself, that is, the hairs will leave a mark on the plastic, which may not even out before the acetone evaporates. It is possible to equalize pronounced irregularities with this method, but it is quite difficult to achieve a smooth surface.
The advantage of this treatment is the selective application of acetone, which avoids smoothing sharp corners. After all, a pyramid was built for Cheops, not a cone, right?
An attempt to create a special tool for manual processing was a device called Makeraser. Basically, it's a simple felt-tip pen with a reservoir filled with acetone or acetone glue and a built-in scraper to remove models from the platform. From a practical point of view, this tool is best suited for gluing parts of a model or applying ABS/Acetone glue to the build bed just before printing to combat underlayer curl.
Acetone dip
Failed surface leveling by dip
A more promising and simpler method is acetone dip.
Exposure of the ABS model in undiluted acetone for about 10 seconds is sufficient to dissolve the outer layer of the model. The specific exposure time may vary depending on the quality of the original model and the concentration of acetone. Since the sale of pure acetone is regulated, a technical solvent can be used.
After exposure, the model must be exposed to air until the acetone has evaporated. The process may take about half an hour.
Although this method is quite fast, it is difficult to control the process. With excessive exposure, the model will simply begin to dissolve, quickly losing small features. In addition, contamination of acetone with plastic of the same color can lead to streaks on subsequent models dipped in the same solution. A more controlled process is acetone vapor treatment.
Probably the most efficient way to get glossy ABS models. This method requires placing the model in a container with a small amount of acetone at the bottom.
The model itself should not come into contact with acetone, so the model should be placed on a platform or hung above the surface of the solvent. When installing on a platform, the material properties of the stand should be taken into account. Wood is not suitable for this task due to its porosity: the bottom surface of the model will stick to the wood, and it will be quite difficult to separate it. The best option is to use a metal stand.
It is advisable not to use wood as a platform
After placing the model, the container must be heated to increase the temperature of the acetone. Acetone also evaporates at room temperature, but too slowly. Please note that boiling acetone is not recommended, as this will cause condensation to accumulate on the model, which in turn can cause streaks. Thus, for best results, do not exceed the temperature threshold of 56°C.
A safe, homemade steamer that uses boiling water in an external pot to heat the acetone in an internal one.
Holding time varies greatly with the temperature of the acetone. So, when boiling, only a few seconds can suffice, while experiments at room temperature required up to 40 minutes of exposure. Fortunately, using a transparent container, you can determine the readiness of the model "by eye".
As with dipping, the completed model should be aired out before the outer surface hardens, avoiding unnecessary physical contact.
Both when immersing models in acetone and when working with steam, the wall thickness of the models must be taken into account. The shell must be thick enough to withstand the inevitable loss of the outer layer. In addition, especially subtle features may simply dissolve, and sharp corners will be smoothed out.
Safety Instructions
Successful Acetone Vaporization of an ABS Model
Acetone is not considered to be highly toxic, but care must be taken nonetheless. Inhalation of vapors can lead to pulmonary edema and pneumonia.
A sign of poisoning is a feeling of intoxication, accompanied by dizziness. In addition, acetone causes irritation of the mucous membranes. When working with acetone, do not neglect personal protective equipment - goggles and gloves.
Particular attention should be paid to the flammability of acetone. Air mixtures with an acetone concentration of up to 13% by volume are explosive - when processing with acetone vapors, it is strongly recommended to work in a well-ventilated room and, if possible, use an exhaust hood. Do not use an open fire to heat acetone: since solvent vapors are heavier than air, they will displace air from the vessel, and once outside, they will cool and come into direct contact with the fire with all the ensuing consequences. It is also not recommended to tightly close the vessel, especially with strong heating, in order to avoid destruction under pressure.
Commercial options
Stratasys Finishing Touch Smoothing Station
In addition to the Makeraser described above, there are commercially produced units for steaming both acetone and other solvents - dichloromethane, butanone, etc.
Stratasys manufactures a little-known but successful Finishing Touch that can process any variation of ABS to a quality virtually indistinguishable from injection molded models. The process is facilitated by the presence of a recirculation system, which saves on solvent and prevents air pollution by potentially dangerous fumes.
Future installation Sky Tech MagicBox
The developers of the new Sky Tech MagicBox device promise compatibility of their device not only with ABS plastic, but also with PLA. True, they intend to achieve this using the same acetone, despite the low solubility of polylactide (PLA) in this solvent. However, even with the ability to work only with ABS, the new device will be a good tool, especially for companies using FDM 3D printing for small-scale production.
Go to the main page of the Encyclopedia of 3D Printing
Post-processing of 3D printed parts (PLA, ABS, SBS, PETG)
Table of Contents
- Remove Supports
- Removing Soluble Supports
- Sanding
- Cold welding
- Filling voids
- Polishing
- Priming and painting
- Pair smoothing
- Epoxy coating
- Metallization
Introduction
FDM technology is best suited for rapid, low-budget prototyping.
Layer lines are usually visible in FDM prints, so post-processing is essential if a smooth surface is to be achieved. Some post-processing techniques can also make a print more durable by changing the degree of its elastic properties, density, structural and textural features.
In this article, we will discuss the most common post-processing techniques in FDM.
Post-processed FDM prints (left to right): cold welded, void filled, raw, sanded, polished, painted and epoxy coated. Photo 3dhubs.com
Removing Supports
Removing supports is usually the first step in post-processing for any 3D printing technology that uses them. In general, props can be divided into two categories: standard and soluble. Unlike other post-processing methods discussed in this article, the removal of props is mandatory and does not result in improved surface quality.
Initial printout with props, poor prop removal, good prop removal. photo 3dhubs.
com
Removal of standard props
Tools
- Wire cutters, needle nose pliers, tongs
- Toothbrush, brush
| Finishing | ★ ☆ ☆ ☆ ☆ |
| Approvals | ★ ★ ☆ ☆ ☆ |
| Speed | ★ ★ ★ ★ ☆ |
| Suitable for | all thermoplastics FDM |
Process
Normally the backups come off the printout without problems, and hard-to-reach places (such as holes or cavities) can be removed from the backup material with an old toothbrush. Proper placement of support structures and correct print orientation can significantly reduce the negative impact of supports on how the final printout will look.
Pros
- Does not change the overall geometry of the part.
- The process is very fast.
Cons
- Does not remove layer lines, scratches or other surface defects.
- If excess material or marks remain from the support structure, the accuracy and appearance of the printout will suffer.
Soluble Support Removal
Instrumentation
- Solvent resistant container
- Thinner
- Ultrasonic cleaner (optional)
| Finishing | ★ ★ ★ ☆ ☆ |
| Approvals | ★ ★ ☆ ☆ ☆ |
| Speed | ★ ★ ★ ★ ☆ |
| Suitable for | all thermoplastics FDM |
Process
Soluble support standard materials are removed from the printout by immersing it in a reservoir of the appropriate solvent.
Supports are usually printed:
- HIPS (usually with ABS)
- PVA (usually with PLA)
A glass container like a preservation jar is fine. Any non-porous vessel is suitable for water treatment. To quickly remove props from HIPS/ABS printouts, you will need a solution of equal parts D-limonene and isopropyl alcohol. Many other support structure materials such as PVA (with PLA) dissolve in normal water.
Pro Tips
Use an ultrasonic cleaner to shorten the solution time and change the solvent as it becomes saturated. A warm (not hot) solution works faster - heating is useful if there is no cleaner.
Pluses
- Complex geometry is allowed for which the standard method of removing props is not possible.
- Smooth surface at the support points.
Cons
- Improper dissolution of the supports can cause discoloration and skewed printouts.
- Does not remove layer lines, scratches or other surface imperfections.
- May cause small holes or holes if soluble material seeps into the object during printing.
- 9
Skok
SHIKS SHIC ABS ABS ABS ABS PROBECTION
Instrumentation
- FORECTIONAL PREASE with grain
, 220, 400, 600, 1000 and 2000
- FORECTIONAL PREASE with grain
- Cleaning cloth
- Toothbrush
- Soap
- Face mask
| Finishing | ★ ★ ★ ★ ☆ |
| Approvals | ★ ★ ★ ☆ ☆ |
| Speed | ★ ★ ☆ ☆ ☆ |
| Suitable for | all thermoplastics FDM |
Process
Once the props have been removed or dissolved, sanding can be done to smooth the part and remove any obvious defects such as smudges or prop marks.
Which sandpaper to start with depends on the thickness of the layer and the quality of the print: for layers of 200 microns or less, or for prints without blotches, you can start with sandpaper at P150. If there are blobs visible to the naked eye, or the object is printed with a layer thickness of 300 microns or more, stripping should begin with P100.
The process can be continued up to P2000 grit (one approach is to go to 220, then 400, 600, 1000 and finally 2000). Wet sanding is recommended from the very beginning to the very end - this will avoid excessive friction, which can lead to an increase in temperature and damage the object, as well as contaminate the sandpaper itself. Between sanding, the printout should be cleaned with a toothbrush and washed with soapy water, then wiped with a cloth to remove dust and prevent it from sticking together. Even P5000 can be sanded to achieve a smooth, shiny FDM part.
Pro Tricks
Always sand in small circular motions - evenly over the entire surface of the part.
It may be tempting to sand perpendicular to the layers, or even parallel, but this can lead to gouges. If the part is discolored or has a lot of scratches after sanding, it can be heated a little to soften the surface and allow some defects to smooth out.
Pros
- An exceptionally smooth surface is obtained.
- Further post-processing (painting, polishing, smoothing and epoxy coating) is greatly facilitated.
Cons
- Not recommended for double or single shell parts as sanding may damage the printout.
- The process is difficult in the case of sophisticated surfaces and the presence of small details in the object.
- If the grinding is done too aggressively and too much material is removed, the appearance of the part can be affected. Acetone for ABS Dichloromethane for PLA, ABS
- Sponge Applicator
| Finishing | ★ ★ ☆ ☆ ☆ |
| Approvals | ★ ★ ☆ ☆ ☆ |
| Speed | ★ ★ ★ ★ ★ |
| Suitable for | all thermoplastics FDM |
Process
If the size of the object exceeds the capacity of the printer, the object is printed in parts and then assembled.
In the case of PLA and some other materials, assembly can be done with Dichloromethane or a suitable adhesive (the choice of adhesive depends on the plastic). In the case of ABS, it is possible to "weld" with acetone. The mating surfaces should be slightly moistened with acetone and squeezed tightly or clamped and held until most of the acetone has evaporated. So the parts will be held together by chemical bonds.
Pro Tricks
Increasing the surface area of the acetone contact increases bond strength. Tongue-and-groove to help.
Pros
- Acetone does not change surface color as much as most adhesives.
- After drying, the compound acquires the properties of ABS, which makes further processing easier and more uniform.
Cons
- The bonding of ABS parts by cold “welding” with acetone is not as strong as if the part were printed as a whole.
- Excessive use of acetone can dissolve the part and affect final appearance and tolerances.
Void Filler
Black ABS Print, Filled and Sanded
Tool Kit
- Epoxy (for small voids only)
- Automotive body filler (large voids and joints)
- ABS filament and acetone (only for small voids in ABS printouts)
| Finishing | ★ ★ ☆ ☆ ☆ |
| Approvals | ★ ★ ★ ☆ ☆ |
| Speed | ★ ★ ★ ☆ ☆ |
| Suitable for | all thermoplastics FDM |
Process
Unusual voids may come out after the part has been ground or the soluble props have been dissolved. These voids are formed during printing when the layers are incomplete due to any restrictions on the trajectory of the print head, which is often inevitable.
Small gaps and voids can be easily filled with epoxy and no additional treatment is required in this case. Larger gaps or voids left by assembling a multi-part object can be filled with automotive bodywork filler, but the printout will then need to be re-sanded. Putty works great, is easy to process with sandpaper and can be painted. Moreover, the parts connected by such a filler, or voids filled with it, turn out to be stronger than the original plastic.
Cracks in ABS printouts can also be filled with ABS thinned with acetone, which reacts chemically with the ABS object and seeps into existing voids. It is recommended to make such a putty from 1 part ABS and 2 parts acetone, then it will not spoil the surface if used correctly.
Dichloromethane works on all plastics: ABS, PLA, HIPS, SBS, etc.
Epoxy is also useful if you want to make your 3D printed part more durable
Pros
- Epoxy filler is easy to sand and prime, resulting in an excellent surface for painting.
- ABS solution of the same filament will give the same color so nothing will be visible on the surface.
Cons
- Auto body filler or other polyester epoxy adhesive is opaque when dry and will leave discolored areas on the printout.
- Additional processing is required to achieve a uniform surface.
- If the grinding is done too aggressively and too much material is removed, the appearance of the part can be affected.
Polished
PLA model, polished. Photo rigid.ink
Tools
- Plastic Polishing Compound
- Sandpaper for P2000
- Cleaning cloth
- Toothbrush
- Polishing pad or microfiber cloth
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| Suitable for | all thermoplastics FDM |
Process
Once the part has been sanded, a plastic polish can be applied to the part to give a standard ABS or PLA object a mirror finish.
After the part has been sanded for 2000, it is necessary to remove dust from the printout with a cloth and rinse the printout under warm water using a toothbrush. When the object is completely dry, buff it on a buffing pad or microfiber cloth, adding a polishing compound as you go, such as polishing jewelry. They are designed specifically for plastics and synthetics and give a long-lasting shine. Other plastic polishes, such as those used to polish car headlights, also work well, but some of them contain chemicals that can damage the printout.
Pro Tricks
To polish small parts, place the polishing wheel on your Dremel (or other rotary tool such as a power drill). For larger and stronger parts, you can use a grinder, just make sure that the part does not stay in one place for too long, otherwise the plastic may melt from friction.
Pros
- The part is polished without solvents that can warp it or change its tolerances.
- When cleaned and polished correctly, a mirror-smooth surface is obtained, very similar to cast.
- Polishing and deburring plastics is extremely economical, making this a very cost-effective method of achieving a quality finish.
Cons
- If you want to achieve a mirror-smooth surface, the part must be carefully ground before polishing, which may affect tolerances.
- After polishing, the primer or paint no longer sticks.
Primer and paint
Gray PLA FDM print spray painted black. 3dhubs.com
Tools
- Cleaning cloth
- Toothbrush
- 150, 220, 400 and 600 grit sandpaper
- Aerosol Primer for Plastics
- Finish paint
- Polishing sticks
- Polishing paper
- Masking tape (only if multiple colors are expected)
- Nitrile gloves and matching face mask
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| Suitable for | all thermoplastics FDM |
Process
Once the printout has been properly sanded (it is sufficient to reach P600 when painting), it can be primed.
Aerosol plastic primer should be applied in two coats. This primer is intended for subsequent painting of models, provides an even coating and at the same time thin enough not to hide small elements. Thick primer, which is sold in hardware stores, can clump, and then you have to seriously work with sandpaper. Apply the first spray coat with short pressures from a distance of 15-20 cm from the object, trying to do it evenly. Let the primer dry and smooth out the unevenness with 600 grit sandpaper. Apply a second coat of spray with light, quick pressures, also very gently and evenly.
When the priming is completed, you can start painting. You can paint with artistic acrylic paints and brushes, but a spray gun will provide a smoother surface. Hardware store spray paints are thick and viscous and difficult to control, so use paints that are designed specifically for modeling. The primed surface must be sanded and polished (sanding and polishing sticks, which are used in nail salons, can be purchased online, they are great for our task), and then wiped with a cloth.
The paint should be applied to the model in very thin layers, the first layers should be transparent. When the paint finish becomes opaque (usually 2-4 coats), let the model rest for 30 minutes to allow the paint to dry completely. Carefully polish the paint layer with manicure sticks, repeat the procedure for each of the colors (between each applied paint).
Separate parts of the model can be covered with masking tape so that the colors, if there are several, do not mix. When painting is complete, remove the masking tape and polish the object with polishing paper. Polishing paper, such as 3M or Zona, comes in a variety of grits and is a relatively new product. It is sold in packs in various online stores, and after processing with this paper, the ink layer or topcoat will literally shine - and nothing else can achieve this effect. Apply 1-2 coats of top coat to protect the paint and let it dry completely. The top coat is selected in accordance with the recommendations of the paint manufacturer.
If the topcoat and paint are incompatible, it can render your entire painting job meaningless, so compatibility is very important here.
Pro Tips
Don't shake the can when spraying! It is important not to mix the pigment or primer with the propellant (propellant gas), which will cause bubbles to form in the spray. Instead, the can must be rotated for 2-3 minutes so that the mixing ball rolls like a pearl, and does not strum.
Pros
- Excellent result, if you take into account all the nuances of the process and practice.
- You can do anything with the final look of the object, no matter what material it is printed on.
Cons
- Primer and paint increase the volume of the model, which affects tolerances and can be a problem when it comes to a part of a larger object.
- High-quality spray paint or spray gun increases costs.
Vapor smoothed
Vapor smoothed black ABS printed hemisphere
Tools
- Cleaning cloth
- Solvent resistant sealed container
- Thinner
- Paper towels
- Aluminum foil (or other solvent resistant material)
- Face mask and chemical resistant gloves
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| Suitable for | all thermoplastics FDM |
Process
Line the bottom of the container with paper towels, if possible along the sides.
It is critical that the vapors cannot damage the container and that the container itself is sealed. It is recommended to use a glass or metal container. Apply enough thinner to the paper towels so that they are wet but not soaked - this will also help them adhere better to the walls. Acetone is famous for its ability to smooth out ABS. PLA can be smoothed with a variety of other solvents (dichloromethane works well), but this plastic tends to be much harder to smooth than ABS. When working with any solvents, please follow the safety precautions for handling chemicals and always take appropriate precautions. Place a small "raft" of aluminum foil or other solvent-resistant material in the center of the paper towel-lined container. Place the printout on the "raft" (either side of your choice) and close the lid of the container. Steam polishing can take varying amounts of time, so check your printout periodically. To increase the speed of polishing, the container can be heated, but this must be done carefully so as not to cause an explosion.
When removing the printout from the container, try not to touch it in any way, leave it on the “raft”, take them out together. In all those places where the printout has come into contact with something, there will be defects, since the outer layer will be under-dissolved. Before working with it, let the printout completely “breathe” so that all solvent vapors have evaporated.
Many aerosols and/or solvent sprays are flammable or explosive and their vapors can be harmful to humans. Be extremely careful when heating solvents, always handle them and store them in a well ventilated area.
Pluses
- Many small blotches, as well as many layer lines, are smoothed out without additional processing.
- The print surface becomes extremely smooth.
- The procedure is very fast and can be performed using commonly available materials.
Cons
- Doesn't "heal" gaps, doesn't completely hide layer lines.
- During the smoothing process, the outer layer of the printout dissolves, which greatly affects the tolerances.
- Affects the strength of the printout due to changes in the properties of its material.
Immersion
PLA model immersed in dichloromethane. Photo 3dpt.ru
Tools
- Solvent resistant container
- Thinner
- Eye hook or cog
- Large wire for sculpture or landscaping
- Dryer or drying rack
- Face mask and chemical resistant gloves
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| Suitable for | all thermoplastics FDM |
Process
Make sure the container you are using is wide and deep enough to completely submerge the printout in the solution.
Fill the container with the appropriate amount of solvent - be careful not to splash. As with vapor smoothing, ABS dip smoothing can be done with acetone, which is easy to find in the store, and for PLA, dichloromethane can also work well with ABS, HIPS, SBS, PETG, and many other materials. PLA is quite resistant to solvent smoothing, so it may take several passes to achieve the desired result. Prepare the printout for dipping by screwing a hook or eye screw into it in an inconspicuous place. Pass the wire through the eyelet or wrap the wire around the screw so that the printout can be immersed in the solvent. If the wire is too thin, it will not be able to withstand the buoyant force on the printout, and it will be difficult to sink the object.
Once the printout is ready, use a wire to completely immerse it in the solvent for a few seconds. Remove the printout and hang it by the wire in a dryer or on a drying frame to allow the solvent to completely evaporate from the surface.
After ejection, the printout can be gently shaken to facilitate the drying process and ensure that no solvent has accumulated in the depressions.
Pro Tricks
If an opaque whitish coating appears on the printout after drying, this can be corrected by holding the object over a solvent bath for a while so that its vapor slightly dissolves the surface. This restores the original color of the printout and achieves a shiny outer layer.
Pros
- The surface of the print is smoothed much faster than steam polishing.
- Significantly less fumes are generated than other solvent polishing methods, so this method is less hazardous.
Cons
- The surface is smoothed very aggressively, so you can forget about tolerances.
- Immersion for too long can result in complete deformation of the object and a significant change in material properties.
Epoxy
Black ABS print, half epoxy coated, half uncoated
Tools
- two-component epoxy
- Sponge Applicator
- Mixing container
- Sandpaper P1000 or finer
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| Suitable for | all thermoplastics FDM |
Process
After the printout has been cleaned (preliminary cleaning gives the best end result), wipe it thoroughly with a cloth.
Mix the resin and hardener in the proportion indicated in the instructions, accurately measuring all volumes. The curing process of epoxy resin is exothermic, so glass containers and containers made of materials with a low melting point should be avoided. It is recommended to use containers that are specifically designed for mixing epoxy resins. Incorrect ratio of resin and hardener can result in longer curing time or no curing at all and result in a permanently sticky substance. Mix the resin and thinner as directed in the instructions - carefully, in smooth movements to minimize the amount of air bubbles remaining inside the mixture. Very little epoxy is needed, and most of these resins only work for 10-15 minutes, so plan accordingly.
Apply the first coat of epoxy with sponge applicator, being careful not to build up in crevices and small parts. When the printout is sufficiently coated, allow the resin to fully cure - as described in the instructions that came with it. One coat may be sufficient, but for optimum results it is best to lightly sand the printout with fine sandpaper (on P1000 and above) to eliminate any imperfections.
Wipe off the dust with a cloth and, in the same way as before, apply a second layer of epoxy.
Pros
- A very thin coat of epoxy won't affect tolerance too much (unless the printout has been sanded excessively hard first).
- A protective shell is formed around the object.
Cons
- The layer lines will remain visible, they will only be covered by a smooth shell.
- If too much epoxy is used, it can flood parts and edges, and the surface can appear greasy.
Plating
FDM printed structural element nickel plated with Repliform RepliKote technology
Tools (for home use)
- A galvanizing solution can be obtained by mixing a metal salt, acid and water, but if the proportions are inaccurate and the substances are of insufficient quality, one cannot count on a professional result.
If you buy a ready-made solution (as in Midas kits), you can be sure that the problems with plating are not caused by the solution. | Finishing | ★ ★ ★ ★ ☆ |
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| Suitable for | all thermoplastics FDM |
Process
Electroplating can be carried out at home or in a professional workshop. To do everything right, you need to be well versed in the materials, in what is actually happening - and at home these opportunities are usually limited. In order to achieve excellent surface quality and to have more plating options, including chrome plating, it is best to use the services of professional workshops. The copper galvanization process will be described below as an example.
At home, you can galvanize with copper or nickel, and this coating will then serve as the basis for galvanizing with other metals. It is critically important that the printout surface be as smooth as possible before it is galvanized. Any bumps and lines in the layers will be enhanced as a result of the process. Prepare the sanded and cleaned object for plating by coating the plastic with a thin coat of high quality conductive paint, or with a graphite and acetone solution for ABS printouts. Allow the conductive coating to dry completely, sand if necessary to ensure a smooth surface. At this stage, it is extremely important not to touch the printout with bare hands or to wear gloves, because sweat marks on the object will certainly affect the quality of the galvanization.
Insert a screw or eyelet in an inconspicuous place on the printout and connect it to the negative terminal of the rectifier. This will be the cathode. Connect the copper anode to the positive contact of the rectifier. Fill the container with enough copper plating solution so that the printout is completely covered with it. Immerse the anode in the container and turn on the power. After the rectifier is turned on, immerse the printout in the container, making sure that it does not touch the anode anywhere. Beware! When the object is already in the bath, the galvanization system is active, and contact with the solution, cathode or anode can be traumatic. Set the voltage on the rectifier to 1-3 Volts, and the process will go to full metallization. To speed things up, the voltage can be increased, but not more than 5 volts. When enough metal has deposited on the printout, simply turn off the power and dry the object with microfiber towels. When it's dry, varnish the object to protect it from corrosion.
