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How to smoothen 3d printed objects
Smoothing PLA 3D prints with sandpaper, solvents, and more
Using PLA with an FDM 3D printer can lead to excellent results. The process is fast and affordable, and PLA filament can produce functional printed parts with a good level of strength and stiffness.
But FDM has its drawbacks too. For instance, it produces visible layer lines, which can compromise the appearance and function of printed parts. Furthermore, PLA can be more difficult to work with than other 3D printing materials, as it can’t be smoothed with acetone.
Fortunately, there are several ways to smooth PLA 3D prints, ranging from beginner-friendly techniques like sanding to advanced methods like solvent application. This article looks at the best ways to smooth PLA prints, showing you which technique will work best in a given situation.
Untreated FDM parts have visible layer lines
Although FDM parts can’t easily attain the smoothness of, for instance, SLA parts, there are a number of post-processing techniques that can transform bumpy prints into smooth, rounded, and glossy parts. Some of these options involve adding material to the print (primer spray, epoxy resin), while others involve removing material (sanding, chemical smoothing).
Of course, adding a smooth surface to PLA printed parts will add time and cost to a project, but the results are often worth it. Not only does smoothing improve the appearance of the prints, it allows for less strict printing parameters — greater layer height, for instance — which in turn leads to faster printing.
Below are some of the most common methods for smoothing PLA prints. They should be carried out after preliminary post-processing steps, i.e. the manual removal of supports and large sections of excess material.
Sanding
The most common method for smoothing PLA prints is sanding. This method is highly practical, as it is inexpensive and poses no health risks. However, it is also one of the most time-consuming ways to smooth a print and is not especially suitable for fine features or reaching into deep crevices.
Sanding can be approached in different ways depending on the purpose of the parts and the desired level of smoothness. Large parts may require a sanding block (a piece of wood with sandpaper wrapped around it), while small parts and fine features may be suited to nail files. Though highly efficient, electric sanders are not recommended for PLA parts, as the heat they generate can melt the PLA and warp the part.
Sanding PLA parts requires sandpaper in different grit sizes
For most prints, sanding begins with coarse 200 or 400 grit sandpaper — either loose or wrapped around a sanding block — worked in circular motions over the surface of the part to remove the most extreme protrusions. After the whole part has been sanded, a slightly finer sandpaper is used, working up in increments to 3,000 grit.
Although it may seem like a big undertaking, it is worth obtaining sandpaper in the following grit sizes and sanding for a few minutes with each size:
200
400
600
800
1,000
1,500
2,000
2,500
3,000
With the finest grit sandpaper, a small amount of water can be applied to produce an even smoother finish.
Polishing
For high-shine PLA parts, the sanding stage (which gives a smooth but matte finish) can be followed by a polishing stage, using a cotton cloth and liquid plastic polish.
The technique for polishing 3D printed parts is similar to sanding: with polish applied, the wet cloth should be moved in even circular motions over the surface of the part until it is smooth and shiny.
Priming
Sanding alone can reduce the appearance of layer lines by shaving off the raised “steps,” but another approach is to fill in the crevices with primer spray then sand down the excess primer afterwards. This method works well because primer is easier to sand than PLA itself.
Priming is the most time-consuming way to smooth PLA parts, because primer must be applied in between each round of sanding then left to dry. However, it produces better results than sanding alone.
When priming a PLA print, the part is placed in a well-ventilated area and sprayed evenly with a very thin coat of the primer.
One or two more coatings can be added before the first round of sanding. Alternate priming and sanding is then carried out, finishing with 3,000 grit sandpaper.
Priming and sanding is usually followed by spray painting, as uncoated primer will be susceptible to impact and environmental damage. Also note that very deep cavities should be filled with plastic filler rather than primer.
Epoxy resin
A different type of coating for smoothing PLA parts is epoxy resin, which comes in two parts (resin and hardener) that must be mixed together before use. Unlike primer, which comes in a spray can, epoxy resin can be applied to parts using a paintbrush and is suitable for filling even the deepest holes.
To ensure good adhesion of the epoxy, it is recommended to first carry out wet sanding on the PLA parts with fine-grit sandpaper. Once the part is dry, the epoxy can be applied in generous amounts and spread evenly across the part surface.
Further layers of epoxy can be added until the desired level of smoothness is reached.
Note that the epoxy resin coating may be weaker than the PLA underneath, and bits of the coating may flake or chip off over time.
Generic epoxy resins can be used, but there are also mixtures designed specifically for smoothing 3D prints, such as Smooth-On XTC-3D.
Solvents
One of the big disadvantages of PLA is its resistance to acetone smoothing, a relatively safe-to-use chemical smoothing process suitable for materials like ABS.[1]
PLA prints can only be chemically smoothed using stronger chemicals that require laboratory equipment like nitrile gloves, protective eyewear, fume hoods, and a well-ventilated environment. These chemicals dissolve the top layer of material, resulting in a smooth finish — but they can dissolve other things too, such as plastic containers, work surfaces, and human skin.
Experienced users may smooth PLA parts with chemicals like tetrahydrofuran, dichloromethane, or chloroform.
[2] However, these substances are difficult to obtain and can be dangerous to use.
A safer option is ethyl acetate, a solvent found in ordinary nail polish remover. Nail polish remover can be applied to PLA parts using a cloth or cotton swab, though it is limited in its effectiveness. In general, PLA is not highly suited to chemical smoothing.
Vapor smoothing
A safe and effective method of chemical smoothing PLA parts is to use an automated vapor smoothing machine such as the Polymaker Polysher, which creates a mist of alcohol to gently remove the top layer of a printed part.[3]
Unfortunately, the Polysher is only compatible with Polymaker’s modified PLA products, PolySmooth and PolyCast, which dissolve in alcohol.
Heat gun smoothing
Though not the most precise method of smoothing printed objects, using a heat gun to melt the outer surface of a part is a fast and easy way to remove layer lines.
A heat gun is a device that resembles a hairdryer but is capable of reaching much higher temperatures.
When using a heat gun to smooth PLA parts, it is important to move the gun evenly to ensure consistent heating across the part surface (or place the part on a revolving platter and keep the heat gun steady).
This technique only works on medium-size or large parts that do not have fine features or hollow sections.
As we have seen, there are several ways to smooth PLA prints and reduce the appearance of layer lines. Choosing the right smoothing method (or methods) depends on the nature of the 3D printing project and your priorities. In general, we would recommend:
Priming and sanding for most PLA parts - effective, safe, cheap
Epoxy resin or polishing for cosmetic parts - high-shine finish
Vapor or heat gun smoothing for rapid parts - fast, least labor-intensive
Alternatively, resin 3D printing technologies like SLA and DLP, though more expensive than FDM, are much better at producing smooth parts without layer lines.
[1] Tuazon BJ, Espino MT, Dizon JR. Investigation on the effects of acetone vapor-polishing to fracture behavior of ABS printed materials at different operating temperature. In Materials Science Forum 2020 (Vol. 1005, pp. 141-149). Trans Tech Publications Ltd.
[2] Zhang B. Does Acetone Dissolve PLA? [Internet]. EcoReprap. 2021 [cited 2022Mar1]. Available from: https://ecoreprap.com/dissolve-pla/
[3] Kočí J. Improve your 3D prints with chemical smoothing [Internet]. PrusaPrinters Blog. 2020 [cited 2022Mar1]. Available from: https://blog.prusaprinters.org/improve-your-3d-prints-with-chemical-smoothing_36268/
How to Get Perfectly Smooth PLA 3D Prints – Clever Creations
Are you interested in smooth PLA 3D prints but aren’t sure where to start? You’re not alone! PLA smoothing is one of the most common concerns among 3D printing enthusiasts who want glossy prints without the hassle of working with ABS.
While you won’t find a direct equivalent of ABS acetone smoothing for PLA, there are several other methods you can use to achieve a smooth outer surface on your prints.
Whether you just don’t like the 3D printed look, want to sell your 3D prints, or need a smooth piece for certain applications, PLA smoothing is fast and easy.
In this article, you’ll find the most common products and techniques used in PLA smoothing, how to use them, the benefits and disadvantages of each method, and when one method should be used over another.
What is PLA Smoothing?
PLA smoothing is the process of removing the visible layer lines that are generated on 3D printed parts during the printing process. A smoothed 3D print becomes just that: smooth. The outside of the print loses the 3D printed look and appears more like injection-molded plastic.
PLA is one of the most common 3D printing materials available because it is easy to use, cheap, and readily available. PLA prints at a low temperature and does not have a strong tendency to warp (unlike ABS filament), making it a good choice for beginners.
Recommended:
PLA vs ABS: Which Filament is Better?
There are many methods to achieve a smooth look on PLA prints, and they usually require either by removing the excess plastic that causes the visible layers or filling in the tiny gaps between the layers with some sort of brush-on coating.
Each method has its pros and cons and some are better for certain projects than others.
Why Smooth PLA 3D Prints?
There are several reasons for smoothing PLA 3D prints, but the most common one is aesthetic. Many enthusiasts don’t like the lined look of 3D prints and would prefer to remove them. This is especially true if they are making money with their 3D printer by selling 3D prints, since their customers may not appreciate the rough texture.
You also may need to fill in or remove your layer lines for certain applications. For example, if you are using the print as a master for making a silicone mold, you may want to smooth it so the texture isn’t transferred and so that casting materials like resin end up being glossy instead of matte.
Some of the methods used for smoothing PLA prints, like epoxy coatings, also make your prints more resilient. The coatings seal the layers and protect them from moisture and dirt. This is especially helpful if you plan to use your prints outside.
Even sanding and spray painting your prints gives them more water and heat resistance.
An additional benefit of epoxy coatings is that they can help make your PLA food safe.
Methods to Smooth PLA Filament Prints
XTC-3D
XTC-3D is a high-performance two-part epoxy resin coating formulated to smooth 3D prints. Epoxy resin generates heat as it cures, so typical epoxies can warp 3D prints made from low-temperature materials like PLA. XTC-3D is formulated to cure at a lower temperature, so it won’t damage your prints.
Like most resins, XTC works by mixing the dormant resin with a proportionate amount of hardener. Once the hardening agent is added, the resin will go from liquid to solid within a certain amount of time. While it’s still in its liquid phase, you can paint a thin layer of it on your print and let it cure.
Resin coats like XTC are a great option for smoothing 3D prints because they are relatively simple to use and produce great results.
The resin coating fills in the layers and adds a glossy shine. You can even sand and paint the resin coating as needed to easily achieve the look you want.
Epoxy resins should be handled with care and proper personal protection equipment. Always use XTC-3D in an area with good ventilation (while ideally wearing a respirator) and wear protection like latex or nitrile gloves and goggles to protect your skin and eyes. Be sure to check the product’s MSDS for more information on safe handling.
XTC-3D - High Performance 3D Print Coating - 6.4 Ounce Unit
Check PricePros:
- Paints on easily
- Clear glossy finish
- Protects your prints
Cons:
- Expensive
- Fumes while uncured
3D Gloop
One of the most versatile 3D printing products you can buy, 3D Gloop is an adhesive meant for coating the print bed and gluing 3D printed parts together. However, it also works well as a brush-on coating to smooth PLA, ABS, or PETG 3D prints.
Unlike resin formulas like XTC-3D, you don’t need to mix or otherwise prepare 3D Gloop—you can brush it on in thin layers directly from the bottle and let it dry. They have formulas specifically made for different types of filament, so make sure you are using the PLA product for smoothing PLA parts.
3D Gloop does produce a lot of fumes while in use, so always use it in a well-ventilated area or with a respirator. You should also wear gloves and goggles and try to avoid direct contact with your skin (and be sure to wash it off quickly if skin contact does happen). If you also resin 3D printing, you might already have this equipment at hand.
Recommended:
Resin vs Filament 3D Printers: What’s the Difference?
Pros:
- Easy to use
- Versatile
- Made for 3D prints
Cons:
- Hazardous fumes
Sanding and Painting
Image: AxeCatAwesome via Reddit
Sanding PLA can give great resultsThe easiest and most common way to smooth PLA 3D prints is to sand and paint them.
This process is the most time-consuming, but it yields excellent results when done thoroughly. With sanding, you are physically removing the layer lines, whereas with other methods, you are filling them in.
Sanding and painting will give you the most control over your finished piece. If you want to 3D print a helmet or create 3D printed cosplay armor, this is the method to go for.
To sand a PLA print, start with a rough quality sandpaper like 100 grit and sand down all the layer lines and areas you want smooth. Use the next size like 200 grit to sand it again, and keep repeating the process while you work your way up to finer sandpaper sheets.
Image: 3D Printed Props via Youtube
Make sure you don’t skip grits when sanding PLAYou can keep sanding until you reach 2000 grit paper for a very smooth 3D print surface, but this may be more than you need for your print. If you plan to prime and paint your piece, you likely won’t have to go that high. Assess your print after each grit and stop when you reach the texture you want.
You can use a wood filler or other filler primer before sanding to fill in some of the layers. This will cut down on a lot of the sanding needed and give your print a nice surface texture for holding paint.
From there you can paint your print as needed using whatever type of paint you prefer. Spray paint works well for large prints, while gloss paint adds shine to your new smooth surface.
Keep in mind that wet sanding (using wet sandpaper or keeping your print submerged in water while sanding) is best for PLA prints since it keeps the friction from melting the plastic and keeps you from inhaling the dust particles from the PLA. It can take a while to finish using this method, but it holds paint very well and looks great.
3M 88619NA 99419 Sand Paper, 9" x 11"
174 Reviews
Check PricePros:
- Gives you the most control
- Most affordable option
Cons:
- Time-consuming
- Takes a lot of effort
Heat Gun
Image: Tinkerine via Youtube
Be careful not to overheat your PLA prints when smoothing with a heat gunIf you want a non-chemical method that doesn’t require quite as much elbow grease as sanding, you can try using a heat gun.
This method can be very effective at smoothing 3D prints when used correctly. However, it is rather difficult to do without accidentally melting your prints (especially ones made from PLA), so be sure to practice on failed or broken prints first.
Smoothing a PLA 3D print with a heat gun melts the outside layers of plastic just enough to remove the layer lines and give the print a shiny gloss. You carefully move the heat gun around the print, never staying on one area too long in order to heat the whole print evenly. When the surface of the print looks wet, you can turn off the heat gun and let the print cool.
Recommended:
How to Melt and Dissolve PLA Filament
This is a helpful technique to quickly get a smooth, shiny look with a tool you might already have on hand. Since it’s so difficult to get consistent results, this method is probably best kept as a last resort or when the results don’t matter as much.
Wagner Spraytech 0503008 HT1000 Heat Gun, 2 Temp Settings 750ᵒF &.
..
Pros:
- Quick
- Uses a common tool
- Gives a shiny surface
Cons:
- Hard to do well
- Results are inconsistent
PolyMaker PolySmooth PVB Filament
Image: Polymaker
Printing under similar settings and conditions as PLA, PolySmooth is a special low-temperature filament that can be smoothed with isopropyl alcohol. For fans of the ABS acetone smoothing, this is one of the closest equivalents you can get to that process with PLA or PLA+ filaments.
PolySmooth is easy to use. It prints at a low temp like PLA and doesn’t require a heated bed or 3D printer enclosure. You can spray alcohol onto your finished model and have a smooth print within minutes. The alcohol breaks down the outermost layer of plastic, leaving behind a shiny and smooth surface similar to that of a vapor-smoothed ABS.
Image: Polymaker
You can also use the PolyMaker Polysher to smooth 3D prints.
Similar to a wash station for resin prints, the Polysher machine evenly coats the prints with vaporized alcohol. You can set the start and end times for the Polysher, ensuring smooth 3D prints every time.
While you don’t need to purchase the Polysher to use PolySmooth, it is a good way to automate the smoothing process if you have a lot of prints to do. It gives more consistent results across many prints.
Polymaker PolySmooth PVB Filament 1.75mm 3D Printer Filament Green...
Check PricePolymaker Polysher - Post Processing Device to Smooth Print Surface...
Check PricePros:
- Prints like PLA
- Safer than vapor smoothing
- Uses isopropyl alcohol
Cons:
- Costly
Chemical Smoothing
If you are wondering if there are chemicals available that smooth PLA similar to how acetone smooths ABS, the short answer is yes. There are some chemicals like ethyl acetate that can vapor smooth PLA, but they are not ideal for many reasons.
We also don’t recommend using them since they are highly toxic (especially when vaporized), expensive, and difficult to source. Ethyl acetate in particular poses a significant health hazard if inhaled and is highly flammable.
With products like PolySmooth on the market, you can already smooth 3D print layer lines without needing to use hazardous chemicals.
Abrasive Smoothing Methods
Abrasive smoothing methods like tumbling and sandblasting are another possibility to smooth 3D prints. These methods are fairly versatile because different tumbling media and blasting mixtures will give you different results.
However, the processes tend to work best with metal-filled PLAs. Regular PLA prints have mixed results. Sticking to the best PLA filament brands does help get better results.
Recommended:
The 10 Best PLA Filaments for 3D Printing
Tumbling 3D prints has been met with limited success. Vibratory bowls tend to work better than rotary tumblers.
Using an actual tumbling media instead of the cheaper options like steel nails/shot or walnut shells also gives more consistent results.
Tumbling regular PLA prints usually softens the layer lines but doesn’t completely remove them. Metal and wood-filled PLA filaments, on the other hand, tend to have better results in a tumbler and look nicely polished and smoothed from the process.
Sandblasting is another option for smoothing PLA prints that offers varied success. Like tumbling, how efficient sandblasting is depends on the media used. Using fresh sand produces the best results. Like with tumbling you usually won’t completely remove your lines, but it will make them less noticeable.
Frequently Asked Questions
What is the best way to smooth PLA prints?
The “best way” really depends on what you’re trying to accomplish with your finished print. If you just want it to look nice and smooth with minimal effort, XTC-3D resin coating is probably your best option.
However, this adds another layer of materials on top of your print, so if you plan to paint it afterward, you will lose your small details.
If you want more control over the detailing of your smoothed prints, sanding is the best method to use. Since you are doing the process by hand, you have the most control over where the sandpaper goes. This method is best when used on prints that are going to be painted after.
Finally, for a quick smoothing effect that still leaves most details and doesn’t require much time, using PolySmooth filament instead of your usual PLA is a fast and easy way to get smooth results, so this will be the best option for everyday prints or when you need to smooth many prints quickly.
How do you smooth PLA without sanding?
To smooth 3D prints without sanding, you can use a liquid coating or filler primer to fill in and seal the layers. XTC-3D and 3D Gloop are the best choices for this, but there are other products available as well.
You can use the heat gun method detailed in this article, but that one takes quite a bit of practice to use well and doesn’t always produce consistent results.
Can you acetone smooth PLA?
No, acetone does not react with PLA plastic in the same way it does ABS, so it will have little to no effect on your 3D print. ABS is acetone soluble, meaning it will break down in acetone. PLA has few chemical reactions (and even less so that work like acetone and ABS), so finding a chemical smoother is not feasible.
If you want the experience of printing with PLA and the easy smoothing of acetone, you’ll need to buy PolySmooth or some other filament made for easy post-processing.
Can you smooth PLA with heat?
Yes, you can use heat to smooth your PLA parts, but your results will vary since it is very easy to damage your prints this way. The best way to heat smooth 3D prints is to only heat the outermost layers of plastic. Being too aggressive will also melt or warp the inside layers, causing the print to deform.
Heating the print in an oven or similar appliance often results in uneven heating. Your prints can overheat or burn in some areas while other areas haven’t even started to smooth.
This is because the heat is coming from a static source, so it doesn’t distribute evenly within the oven.
Image: Tinkerine via Youtube
Your results with smoothing PLA in an oven will varyUsing a heat gun gives you more control to evenly heat the print and overall better results than a static heat source, but even that produces inconsistent results. More aggressive heat sources like an open flame almost always damage the prints, even when they can be moved around.
Does isopropyl smooth PLA?
No, isopropyl alcohol (IPA) will not smooth PLA. However, you can get the desired results with Polymaker’s Polysmooth. This is a special PLA filament that has been treated to be more responsive to IPA.
Can you vapor smooth PLA?
Yes, technically you can smooth PLA 3D prints using a vapor deposition process, but the chemicals required are not safe for human exposure.
How do you smooth a 3D printed figure?
There are a few ways to smooth out a 3D printed figure.
One is to use sandpaper to lightly sand down the rough edges. Another is to use a heat gun to slightly melt the edges and give them a smoother appearance.
You can also use chemicals like acetone or XTC-3D to smooth out the surface of the print. Whichever method you choose, make sure to take your time and be careful not to damage the figure.
Finally, the best way to create a smooth 3D printed figurine is by using resin 3D printing instead of FDM printing. There are plenty of 3D printers for miniatures that work well for this purpose.
How do I get a smooth finish with PLA?
There are a few things you can do to get a smoother finish with PLA. First, make sure your printer is calibrated correctly, for example by using a temperature tower to set the right temperatures. This will help ensure that the layers are printed evenly.
Second, use a higher-quality PLA filament. Some brands of PLA filament are known for having a smoother finish than others.
Recommended:
The 10 Best PLA Filaments for 3D Printing
Finally, try using a different nozzle size.
A smaller nozzle size (and thus smaller layer heights) will result in a smoother finish.
Final Thoughts
Whether you enjoy the cleaner look of finished prints or need a smooth surface on your prints for functionality, you have several options for making your PLA prints look amazing.
Smoothing layer lines from PLA isn’t as easy as some other 3D printing materials, but there are several methods and products available to help you do it as painlessly as possible. From brush-on epoxy resin products that fill in layers to special filaments to basic sandpaper, there is a smoothing method that works for most projects.
Do you still have questions about smoothing PLA prints? Let us know in the comments!
How to smooth 3D printing?・Cults
Objects created with a 3D printer don't always look as good as they should. Even if visualization of 3D printed parts is usually acceptable, this may not be enough if the object is for sale or display. Some people just want a perfectly smooth and shiny surface for 3D printing.
Fortunately, it is possible to achieve this level of perfection with the help of some suitable tools. This guide will show you how to smooth out ABS and PLA 3D prints for the best results.
The FDM 3D printer opens up endless possibilities for creating PLA 3D prints. However, parts may be printed with bad layers that need to be removed. If you want to give your 3D printed parts a shinier look, there are some easy ways to align your 3D printed PLA.
Use spray paint and polyurethane
The sanding method used to be the most common technique for leveling 3D printed PLA. Today there are new alternatives. You can use spray paint mixed with polyurethane to line up 3D printed PLA parts. To do this, you need to purchase the right tools:
- spray paint,
- polyurethane,
- fan for drying parts.
The smoothing process is one of the simplest. First of all, it is necessary to clean the product so that dust or other dirt does not linger on the surface of the object.
Use a spray can to cover the 3D print with a layer of paint. Then a layer of polyurethane can be applied to the part. Be very careful and place the freshly coated 3D print under a fan to speed up the drying process .
After a few minutes, you will find that the mixture of polyurethane and paint starts to fill in unwanted holes and imperfections on your PLA 3D print. Once completely dry, the part can be recoated with the mix to remove any remaining surface defects . This method is less tiring than sanding.
Opt for XTC-3D Clear Epoxy
Although highly effective, using a mixture of paint and polyurethane to line a room can be too messy for some people. There are other alternative methods for anti-aliasing PLA 3D printing. Transparent epoxy resin XTC-3D has been specifically designed to align PLA 3D parts for an optimal finish . The product consists of two bottles that need to be mixed for 3D printing.
Remember to mix the product well and follow the instructions correctly.
Using a brush, apply the resin to the printed parts. The dried product will harden into a smooth transparent layer. PLA 3D printing becomes smoother and shinier. XTC-3D can also be mixed with dyes and stains if you wish to color your parts. You can also add effects such as metallic highlights or palettes.
Use 3D Gloop
This adhesive has been specially developed for smoothing PLA 3D prints. 3D Gloop can be used for various purposes. To smooth out a 3D print with this product, simply apply it to the printed part with a brush. It works like the XTC-3D, except it only has one bottle. This is a great advantage if you only want to use a small amount of glue. However, 3D Gloop is not without flaws. The product contains a number of toxic components. It should be used in a well ventilated area.
Acetone is a chemical stripper used by professionals to sand and clean certain materials. Due to its high toxicity, it should be handled with care in a well-ventilated area. Acetone can be used to level ABS 3D printing.
The process does not require a lot of equipment. All that is required is metal or glass container .
Also add a few millimeters of acetone. In supermarkets, this product can be purchased for less than 2 euros. You will also need a stand to hold the part to be smoothed and a heating plate. To smooth the ABS 3D print, add 2-4 millimeters of acetone to the container. Place it on a hot stove and boil acetone at 90 to 120°C. At this temperature, the product releases the steam needed to begin flattening the ABS 3D print.
When the acetone has boiled off sufficiently, place the substrate in the container. Make sure the acetone is not touching the part that will be in contact with the 3D print. After the holder is correctly installed, place the printed part on it and close the container. Wait a few minutes for the acetone to take effect. The amount of time depends on the shape and size of the part, the desired level of smoothness, and steam output .
The result is simply amazing. At the end of the process, your piece is completely smooth and looks like a piece of hand-sculpted art.
Post-processing of 3D printed parts (PLA, ABS, SBS, PETG)
Table of Contents
- Remove Supports
- Remove Soluble Supports
- Sanding
- Cold welding
- Filling voids
- Polishing
- Priming and painting
- Pair smoothing
- Epoxy coating
- Metallization
Introduction
FDM technology is best suited for fast, 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 supports
Tools
- Nippers, needle nose pliers, tongs
- Toothbrush, brush
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| Suitable for | all thermoplastics FDM |
Process
Normally the backups come off the printout without any problem, 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.
Pluses
- 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, print accuracy and appearance suffer.
Removal of Soluble Supports
Instrumentation
- Solvent resistant container
- Thinner
- Ultrasonic cleaner (optional)
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| 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 Tricks
Shorten the solution time by using an ultrasonic cleaner and changing 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 props 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.
Cleaning with a skin
Starched by a sliced ABS ABS ABS PROBECTION
Instrumentation
- EVERTICAL PREASE with grain
on 150, 220, 400, 600, 1000 and 2000 - Wiping cloth
- Toothbrush
- Soap
- Face mask
| Finishing | ★ ★ ★ ★ ☆ |
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| 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 blots 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
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| 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 (for large voids and joints)
- ABS filament and acetone (only for small voids in ABS printouts)
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| Suitable for | all thermoplastics FDM |
Process
Unusual voids may come out after the part has been ground or 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.
Slots 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 show up 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 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
- Wiping cloth
- Toothbrush
- Polishing pad or microfiber cloth
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| Suitable for | all thermoplastics FDM |
Process
Once the part has been cleaned, 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 properly ground and polished, 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
- Wiping 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
After the printout has been properly sanded (it is enough 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.
Pros
- Many small blotches and a lot of layer lines are smoothed out without additional processing.
- The printout surface becomes exceptionally smooth.
- The procedure is very fast and can be done using widely 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.
- Negatively 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
- Heavy 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 printout, half coated with epoxy, half uncoated
Tools
- two-component epoxy04
- 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 a 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 too hard beforehand).
- A protective shell forms 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 using RepliKote technology
Tools (for homework)
3
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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.
