Best Way How to Sand, Smooth & Paint 3D Printed Objects & Surfaces
ByMichael DwamenaReading Time: 15 minutes
3D printing can create some of the most beautiful models out there, but some people wonder how to best sand, smooth & finish their models to get that professional looking quality. I had to do some in-depth research to figure out how to create the best looking 3D printed objects.
So, how do you smooth 3D printed objects like miniatures?
The process to sand & smooth your 3D printed objects is to:
Ensure your 3D printer and its settings are optimized for quality – layer resolution, orientation, flow rate etc.
Print your models at a layer height, ideally at 0.05mm or below. 0.1mm can work well for darker colors.
Clean up your 3D print of supports and any larger imperfections with clippers
Sand and file your model to smooth out layer lines and rough surfaces
Apply a coat primer/filler to your model and wait for your model to dry
Apply a second coat of primer
Give your model a final sanding with finer sandpaper like a 1,200 grit
Clean off the primer dust – spray or paint your model here if you desire
Apply a thin, even coat of epoxy, varnish, or polyurethane to finish the model
After you’ve done the steps above, you should have a very high quality, smooth 3D printed object that you can be proud of.
These are the basic steps, so keep reading through this article for those important details of how to do each step properly, as well as other tips and tricks for awesome results.
You can get a really good-looking print by just removing the original supports from your model, then carefully sanding down your prints without using primer or other products.
If you want to really achieve the best results though, going through the whole sand & smoothing method is how the professionals get their work done.
How to Optimize Your 3D Printer for the Best Smooth Quality
Print at layer resolutions of 0.05mm or 50 microns and below. 100 microns can produce great 3D prints, but if we are talking about the best quality, you’re getting into those invisible layer lines when you are at the 0.05mm mark.
There are many other slicer settings that people overlook when it comes to getting the best quality straight off the bed. This isn’t essential, but it definitely helps out with the final output and getting that professional quality print.
I’d recommend using a proven and reliable Cura Profile such as CH3P’s Ender 3 Profiles which you can find on his website. These have been optimized for you so you can produce some great quality prints right off the print bed.
Another thing that is important for you to calibrate your 3D printer is to test out several temperatures by using a temperature tower. These work by having multiple blocks which have temperature changes within the same print.
So you can test 10 different temperatures all on the same tower, allowing you to inspect which temperatures provide the best quality.
A great temperature tower you can use for your desired material is the Temp Tower PLA, ABS, PETG model from Thingiverse.
One great thing about this is there are G-Code files which are done for you, but I would recommend learning how to change temperatures at specific layers. The video below is a quick tutorial to get you started.
How to Clean Up & Sand Your 3D Prints After Printing – PLA, ABS, PETG
How to Clean Up 3D Prints for Smooth Surfaces
The first step after taking your 3D model off the build plate is to do the initial clean up, which consists of basic support removal, and filing down any large imperfections such as blobs and bumps.
It would take a longer to sand down these larger marks, so using a file is the more efficient method to get this done.
I’d recommend getting yourself a high quality clean up kit, a popular one being the Filament Friday 3D Print Tool Kit from Amazon. It consists of a 38-piece set of printing, cleaning, and finished tools to easily process your models after it comes off the print bed.
Removal tools to get your 3D prints off the bed without damaging it
Needle nose pliers to remove excess filament
Deburring tool to provide a deeper clean to your models
Cutting mat for safety and protection to your work surface
Filing tool to manage those rougher edges and surfaces
Knife clean up kit to remove the excess filament – variety of 13 blades
Diagonal wire cutters to easily cut through filament and other materials
Wire brushes to sweep off the excess filament
Nozzle cleaning pins & brushes
It includes a 3-year warranty and is loved by plenty of 3D printer users out there.
How to Sand 3D Prints for Smooth Surfaces
An assortment of sandpaper is the usual option that 3D printing professionals will use to properly sand their models.
It gives them a gradual rough to smooth transition for models, where the rough sandpaper can tackle large imperfections, then the finer sandpaper can smooth surfaces down nicely.
You want a sandpaper that works effectively and doesn’t tear easily when sanding. A great option that many people are very happy with is the Miady 120 to 3,000 Assorted Grit Sandpaper from Amazon.
Many reviews have talked about how well this has worked for their 3D models, so you can definitely try it out and see how great your final products can be with it.
One great sanding solution that not many people know about are sanding twigs, or plastic sanding needles, a very valuable method to sanding your models and miniatures, especially in those hard to reach areas.
The DuraSand Sanding Twigs from Amazon provides you with 20 sanding twigs of mixed grits. When you go through the reviews of this great product, you see just how many people are using it to level up their 3D modelling game.
One user who has a whole host of sanding blocks, tools, micro-sanders, sanding sponges and all the above found it really hard to get into certain areas of their 3D models.
After ordering these sanding twigs, they were instantly sold once it was put to use. Not only are the sanding twigs durable, the grit is great quality and long-lasting.
The only real downside I could find is that the bags can sometimes mix up grits, or have a little more of an assortment, but other than that, these are a great purchase for you 3D printer hobbyists out there.
How to Use Primer On Your 3D Prints to Smooth Surfaces
When using primer on your models, you should be using the proper technique for the best results.
Rather than spray your models down with long, direct sprays of primer, you should use short, angled bursts while moving the can over the print, almost like a flick. This ensures that your model gets more even coverage all around.
The video below goes into some great details about priming, and also shows that flicking technique further in the video.
A staple primer that is used throughout the 3D printing community is the Rust-Oleum Painter’s Touch 2X Ultra-Cover Primer in gray. It provides your models with a Double Cover Technology that enhances not only the quality, but the speed of your projects.
This durable spray is protective and fast-drying, easily sticking to plastic models. It’s a #1 Best Seller on Amazon, coming at a very affordable price to level up your 3D printing game.
You want to apply two coats of primer/filler to your cleaned up model, then you sand it down to get an amazingly smooth 3D print.
How to Smooth PLA, ABS, PETG 3D Prints
Once you have cleaned, sanded, primed and sanded your model down again, it should be pretty smooth at this point. We are now moving onto the final step which is giving your models a final coating for that extra smooth finish.
Any type of filament can benefit from being smoothed, but ABS for example can be smoothed quite well with the acetone smoothing method, which requires acetone fumes to slowly dissolve the exterior of a model.
A water-based polyurethane is a great product which helps you smooth out those rougher 3D prints. It doesn’t take long at all, with the video below showing how you can do it in just 1 minute, without those harsh acetone chemicals.
The way to use this for your 3D prints is to lightly brush the wax straight onto your 3D prints with a really thin brush. It works quite similarly to varnish or epoxy which gives that smooth look.
If you’ve done some previous woodworking, you may even have some of this stuff lying around.
This is something that you add to your PLA, ABS, or even PETG prints after you’ve removed all your supports and larger imperfections such as blobs on your model.
It’s still a good idea to do some proper post-processing such as sanding and filing for the best results, since it won’t coverup big blobs or chunks of filament.
For those areas which are hard to reach, or you just can’t get to, polyurethane is a very useful product to have.
Do keep in mind, this wax tends to pool and build-up, so you want to ensure that the product is being spread out evenly. You’ll notice it fills up those gaps/holes which can take away from your model’s details.
Using a coat too thick means you will definitely lose detail, which is even worse for your high quality miniatures printed on an FDM filament printer.
For some simple, effective brushes that can apply those thin coats nicely, I’d recommend the Heartybay 10-Piece Nylon Brush Set from Amazon.
Many people describe these brushes as great value for miniature painting and “excellent brushes” that don’t shed or fray like other cheaper ones.
How to Paint Your 3D Prints – Miniatures, Figures & More
Once you have primed your 3D prints, painting should be fairly easy to do since the primer helps paint stick to it.
The methods to paint 3D prints are usually:
Using an airbrush
Using an aerosol paint or primer+paint combo
Using a paintbrush with standard paint
Painting 3D Prints with an Airbrush
Miniac on YouTube is one of the best introductions to painting your 3D models. He has some serious skill and experience in this field, so if you want to get really good at it, he’s your guy.
Using an airbrush is an amazing technique that can really bring life and unique detail into your 3D prints, whether filament or resin.
The video below goes into detail about painting your 3D prints with an airbrush.
Tools you’ll need to start of airbrushing like a professional:
Gravity-Fed Airbrush
Dual-Fan Compressor Kit
Airbrush Thinner
Airbrush Lubricant
Respirator
Nitrile Gloves
The products that Miniac named in the video above, you can find in this list below. They have really positive reviews from thousands of users, a great factor for reliable products.
Gravity-Fed Airbrush
The Iwata-Medea Eclipse HP CS Dual-Action Airbrush from Amazon is a serious purchase that can bring you amazing quality for years to come. I think it’s important to invest into something that you can rely on, as well as something that is versatile.
The performance of this airbrush is top-tier and is really a benchmark for excellence for all-purpose airbrushes out there. Many users comment on how this is one of the best airbrushes for beginners to start learning the painting craft.
Along with the gravity-fed airbrush, it’s important to have a compressor with a tank.
Dual-Fan Compressor Kit
The Master Airbrush’s HP Coolrunner Compressor Kit from Amazon does the trick, a perfect addition to go with the Iwata-Media Eclipse Airbrush. It’s one that doesn’t run constantly, so you can quickly disconnect it as you need.
One review mentions the very same combination of this compressor kit and the airbrush, while stating how much better this kit is compared to their last one. It has a moisture collector, an on/off switch, and only activates when more pressure is needed.
Another sweet little feature is the two airbrush holders if you ever need it. Some compressor kits can be pretty loud, even the premium ones, but this one comes at a great price and is really quiet.
You don’t need some complicated assembly, simply plug it in, and it starts to work flawlessly.
By the way, it comes with a 100% satisfaction, 5-year guarantee so you can have a worry-free experience with this machine.
Along with your compressor kit, an airbrush thinner is necessary for operation.
Airbrush Thinner & Flow Improver
The Vallejo Model Air 200ml Paint Thinner from Amazon is a non-toxic, non-flammable product that helps your painting workflow. It’s pre-thinned and works straight from the bottle.
Your colors extend with the use of this paint thinner, as well as delaying the drying times. They recommend that you add a few drops of thinner to your colors while airbrushing.
Being able to thin the paint without having it dilute the color is essential for the best quality paintings. Vallejo products are top quality so you can definitely put your trust into this.
The Vallejo Airbrush Flow Improver is another addition that should help you improve the quality of your 3D print paintings.
Airbrush Lubricant
The REGDAB Airbrush Lubricant 1 oz. from Amazon is an addition to your airbrushing experience that takes you up to the next level. Many users mention how when they started using it, they get some “butter smooth action” when operating the airbrush.
It allows you to keep your airbrush in tip-top shape. You just need to put a little on the moving metal parts of your airbrush such as the trigger stem and lever, and other areas like the needle.
Needle friction is easily eliminated with this product.
The Krylon Fusion All-In-One Spray Paint from Amazon is a great option for spray-painting your 3D models because it mixes primer and paint, all into one effective solution.
It provides amazing adhesion, durability, and even rust protection for other types of surfaces. Although you’ll be using it for your 3D models, it has real versatility, being able to be used on surfaces like wood, ceramic, glass, tile and so on.
The quick drying aspect is a great benefit, where it dries to the touch in just 20 minutes and is dry enough to handle after 1 hour. For recoating, you’ll want to be within the 2-hour window, or after 48 hours.
The video below goes into how to paint your 3D printed parts like a professional.
Painting 3D Prints with a Paintbrush
This one is a very simple process, just like back in the school days. You pull out some paint and paintbrushes and get to work.
Tons of 3D printer users choose the Crafts 4 All Acrylic Paint Set of 24 Colors on Amazon. It provides you with a whole host of colors and visuals for you to get creative on your 3D models.
Whether you are a beginner, a student, or a professional, this high-performance paint, full of vibrant colors should give you exactly what you need to paint your 3D print models nicely.
It comes with 3 nice brushes with fine tips to get you started.
As usual, you should use a primer on your models before painting them.
How Do You Smooth PLA Without Sanding?
To smooth PLA without sanding, you can use a combination of spray paint and fast-drying polyurethane clear satin spray. Start with spraying a good amount of spray paint on your model then quickly spray a layer of the polyurethane. Use a fan to dry the spray quicker, and repeat several times.
The video below shows how you smooth PLA without sanding. It does require a lot of time and effort to do this, with the last layer needing a 24-hour resting period for optimal results.
Many people talk about a chemical called ethyl acetate to smooth PLA, though it is a pretty dangerous chemical which comes in different dilutions. Some people claim it doesn’t work, though they may have been using a version which was too diluted.
The verdict among 3D printer users isn’t conclusive and seems to require more specialized equipment due to the safety aspect of these chemicals.
The video below goes through the processof trying to smooth PLA with acetone. I think acetone can smooth PLA, but more so with the spools which have a lesser level of pureness.
PLA that is impure is more likely to be smoothed by acetone, compared to the more high quality stuff, which is why some PLA filaments got smoothed better than others.
You also have access to a 3D print polisher known as XTC-3D Smooth On Coating from Amazon. It’s a popular, high-performance 3D print coating which doesn’t require melting or heat to get your 3D models looking nice.
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