If you’ve ever pulled a fresh 3D print off the build plate, you know the job isn’t quite finished yet. Those layer lines, Unterstützungsmarken, and rough edges can keep your part from looking professional or performing at its best. That’s where 3D printing post-processing comes in. But what processes are generally used in 3D printing post-processing? In diesem Leitfaden, we’ll walk you through everything you need to know about transforming your 3D prints from good to great.
Why 3D Printing Post-Processing Matters
Before diving into the specific processes, let’s talk about why post-processing is so important. 3D printers build parts layer by layer, which naturally creates a textured surface—especially with lower print resolutions. If your part needed supports, you’ll likely have extra imperfections where those supports were attached. Post-processing fixes these issues and offers even more benefits:
- Smoother Surfaces: Reduces the appearance of print layers and refinements for a polished look.
- Stronger Parts: Reinforces prints to add strength and durability for functional use.
- Added Functionality: Improves properties like UV resistance, weather resistance, and conductivity.
- Aesthetic Finishing: Transforms the surface appearance to create visually striking parts.
Every 3D print can benefit from some form of post-processing, whether it’s a simple sanding job or a more complex chemical treatment. Let’s explore the main categories and processes.
The First Step: Support Removal
Before any other post-processing can begin, you’ll probably need to remove support structures. Unless you’ve optimized your print for supportless 3D printing, those supports are essential during the printing process but become unnecessary once the job is done.
Most supports can be snapped off by hand, but even well-designed supports leave behind imperfections. That’s why it’s recommended to post-process the entire part after support removal to smooth out these areas. For a cleaner solution, dual extrusion printers can use soluble supports that disintegrate in water, leaving no trace behind—perfect for parts where post-processing might be tricky.
3D Printing Post-Processing Categories
All post-processing methods fall into three main categories: subtractive, additive, and property changing. Each category has its own set of processes, and choosing the right one depends on your part’s material, geometry, and desired outcome.
Subtractive Post-Processing: Removing Material for Smoothness
Subtractive post-processing is the most common category, and as the name suggests, it involves removing material from the part’s surface to make it more uniform and smoother. Here are the key processes in this category:
Schleifen & Polieren
Difficulty: Low to Medium | Smoothness: Hoch
Sanding and polishing are the workhorses of 3D print post-processing. Both techniques remove surface layers using abrasive materials, but they differ in execution. Sanding uses coarser grit sandpaper and tools to tackle larger blemishes like support remnants or print irregularities, reducing the visibility of those pesky layer lines. Jedoch, sanding leaves a gritty (though more uniform) surface, and very coarse sandpaper can create new scratches.
Polishing takes over after sanding, using finer sandpaper, steel wool, polishing paste, or cloth to produce an even smoother surface. The best part? These methods are simple and affordable, making them accessible to hobbyists and professionals alike. The downside? They’re labor-intensive, especially for larger parts or batches, and they struggle with hard-to-reach cavities.
Tumbling
Difficulty: Medium | Smoothness: Medium to High
Tumbling is like a spa day for your 3D prints, but with a rough-and-tumble twist. A tumbling machine consists of a vibrating vat filled with lubricating fluid and abrasive media—specialized stones that wear down objects based on their size, Form, and hardness as they tumble together. Just place your 3D printed part in the vat, set the timer, and let the machine do the work.
Tumbling is great for batch processing multiple parts at once, and it works for larger parts too, as long as you have a big enough machine. Jedoch, it requires some expertise to pair the right abrasive media with your part and determine the correct processing time. Keep in mind that complex shapes might lose detail, and sharp edges can become slightly rounded.
Abrasive Blasting (Sand Blasting)
Difficulty: Medium | Smoothness: Medium
Abrasive blasting, or sand blasting, blasts abrasive material onto 3D printed parts at high pressure. For large parts, this can be done in an open environment, but smaller parts usually go into a containment chamber that collects and reuses the abrasive material. You can choose from a range of grits depending on your part’s geometry and desired finish—sand is common, but plastic beads can also be used for different results.
This method is less effective on very rough parts or those with high layer heights, and it only treats surfaces reachable by the blasting stream, so complex geometries and cavities might be out of luck. It’s also slower for processing multiple parts simultaneously since the blasting tool can only treat limited areas at a time.
CNC -Bearbeitung (Milling)
Difficulty: Hoch | Smoothness: Sehr hoch
CNC milling is like the precision sculptor of post-processing. It uses a computer-programmable drill that moves (and sometimes rotates) in three axes to carve out geometries, using G-Code just like 3D printers, but with a milling bit instead of a filament extruder. It’s highly accurate, with tolerances ranging from 0.005” to 0.00005”.
While it’s not cost-effective to mill an entire 3D print, it’s perfect for smoothing specific areas that need extreme precision. You can even 3D print a part in a rough finish and then mill it to perfection, saving material in the process. Just note that CNC machining can’t produce certain geometries and wastes more material than 3D printing.
Chemical Dipping
Difficulty: Hoch | Smoothness: Hoch
Chemical dipping, or acid dipping, involves submerging parts in a chemical bath that eats away at the surface. It uses caustic materials like lye, Natriumhydroxid, or dichloromethane, so it should only be done by experts in facilities with proper safety features. The key is choosing the right chemical for your 3D print’s material— it needs to be abrasive to the print material.
Timing is everything here: too short, and the part won’t be smooth enough; too long, and you might ruin it entirely. You also need to watch out for air bubbles trapped inside the print, which can prevent the chemical from treating the surface— gently moving the part in the bath helps release these bubbles. Chemical dipping is ideal for complex geometries since it treats all surfaces simultaneously, but the size of the container limits the part dimensions you can process.
Additive Post-Processing: Adding Material for Strength and Smoothness
Additive post-processing puts additional material directly onto printed parts, making it highly efficient for smoothing while adding strength and other mechanical properties. Let’s explore these processes:
Filling
Difficulty: Low to Medium | Smoothness: Medium to High
Filling is like spackling a wall, but for 3D prints. It uses a thick adhesive compound, usually a paste, to fill in notches like the tiny gaps between layers. It’s often used as a first step before sanding or adding more layers. You can choose from a wide range of fillers: paste fillers (like wood fillers or household spackle) are easy to spread and smooth with light sanding; spray fillers are simple to apply but only provide a thin, rougher coating; and resin fillers, which cure either by mixing with a hardener or UV exposure, offer more robustness.
Resin fillers come with various viscosities, cure speeds, and advanced features like UV resistance and high heat deflection temperatures. Some UV-cured fillers can be set in the sun, while others need a specialized UV chamber. Just remember to wear gloves, cover your skin, and keep the workspace well-ventilated when using resins.
Priming
Difficulty: Niedrig | Smoothness: Low to Medium
Primers are the warm-up act for your post-processing routine. They prepare 3D-printed parts for subsequent layers by pre-treating the surface for better adhesion. They’re less viscous than fillers and only smooth very small imperfections, so their main job is to get the surface ready.
Primers come in spray or brush form, with spray primer usually producing a more even coating. For best results, first reduce imperfections and layer notches with sanding or filling, then use a primer made for plastic adhesion that’s suitable for the materials you’ll apply later. Let the primer set for 24 hours or as directed.
Brush Coating
Difficulty: Medium | Smoothness: Medium to High
Brush coating is the artist’s choice for post-processing, using liquid coatings like paint, varnish, Harz, oder Plastik. It’s simple for unique or small batches of parts, but brush strokes can cause inconsistent smoothness—choosing a material with the right viscosity can help avoid this.
For a robust, glatte Oberfläche, try a 2K resin—a two-component mixture of resin and hardener that creates an exothermic chemical reaction to cure over time. There are resins for all sorts of uses: laminating resins for thin surfaces, casting resins for larger volumes, fast and slow curing resins, and even resins with additives like aluminum for enhanced temperature, UV, or chemical resistance. Look for resins with “self-leveling” viscosity to even out brush strokes without dripping. Many coatings can be sanded after drying for a smoother finish, or you can apply an additional coating like 2K resin for extra smoothness.
Spray Coating
Difficulty: Low to High | Smoothness: Medium to High
Spray coating is versatile, scalable, and works for everything from DIY projects to industrial automation. You can choose from a huge variety of materials: paint, varnish, Harz, Kunststoff, rubbers, and more.
For DIYers, a spray can in a ventilated or outdoor space does the trick, but it doesn’t smooth much, so sand first and apply several coats. A spray primer can help the coating adhere. Spray paint enhances aesthetics, while spray varnish protects against chipping, wear, and UV damage.
In industrial settings, robotic arms with spraying tool heads apply coatings in spray booths with air filters. This allows for a wider range of materials, including 2K spray coatings, and results in higher precision and uniformity. It’s great for large parts since it’s only limited by the size of the room, unlike dipping or powder coating which need containers.
Foiling (Vinyl Wrapping)
Difficulty: Medium to High | Smoothness: Medium to High
Foiling, or vinyl wrapping, is like giving your 3D print a new outfit. An adhesive foil made of light metals or plastic is wrapped onto the object, often after priming. You might know it from vehicle wrapping, but it works on 3D prints too with the right material. Depending on the foil, it can increase heat and stress resistance, but it’s often used for aesthetics like smoothing and improving surface quality.
The difficulty depends on your part’s size and complexity. Simple, gently curved shapes are easy, but complex shapes can be impossible to foil uniformly. Foiling is great for adding detailed surface designs—adhesive foils come in a wide range of colors, patterns, and custom prints. You can apply it by hand, stretching the material to avoid air bubbles, and using a heat gun to make application easier. Vacuum foiling automates the process for faster, precise results. Just skip it for complex parts with cavities, as the foil won’t apply uniformly.
Dip Coating
Difficulty: Medium | Smoothness: Hoch
Dip coating is like a quick dip in a material bath for your 3D print. Submerge the part in a vat of paint, Harz, rubber, or another material, remove it after a specified time, and you get an even surface coating. You can redip multiple times for a thicker, smoother surface, and it enhances both aesthetics and functionality, adding strength and resistance to heat, Chemikalien, and weather.
The process has five stages: immersion (submerging at a constant speed), start-up (remaining submerged to let the coating adhere), deposition (removing at a constant rate to deposit a thin layer), drainage (excess material dripping back into the vat), and evaporation (solvent evaporating to leave a solid film).
Hydro dipping, or water transfer printing, is a unique type where the part is submerged in water with a floating layer of material (usually a water-soluble printed film or oil-based paint). The film or paint adheres to the part as it passes through, with water’s surface tension ensuring it curves around any shape—great for gently curving geometries. Dip coating works for complex geometries but requires expertise in the coating material, and the vat size limits part dimensions, though batch processing small parts is possible.
Metal Plating
Difficulty: Hoch | Smoothness: Hoch
Metal plating gives your 3D print a metallic makeover, bonding a layer of metal to the surface through a chemical process. It’s perfect for creating parts with high resistance to heat, impact, weather, and chemicals, or for making conductive parts.
The first step is “electroless plating” to metalize the print’s surface, priming it for plating. This can range from special metal paints brushed or sprayed on to industrial processes with multiple steps: Reinigung, etching, neutralizing, activating, and more. Copper or nickel are common first layers, but silver and gold are possible too.
In the second step, the metalized part is submerged in a bath to deposit metals like tin, platinum, palladium, rhodium, or chrome. In electroplating, it goes into a galvanic bath where anode and cathode ions pass through the liquid, adhering in fine layers 1–50 microns thick. You can build up thickness or deposit different metals with additional processes.
Using a metal-acid solution? Submerge the part for the right duration based on desired thickness, then add a protective coating to prevent oxidation, Korrosion, or tarnishing. Heat treatments can strengthen adhesion and prevent brittleness. Metal plating works well for complex parts but requires many stages and expertise.
Powder Coating
Difficulty: Hoch | Smoothness: Medium
Powder coating, or rotational sintering, heats and rotates a part within a cloud of powdered plastic. The powder melts onto the heated surface, creating a homogeneous, non-porous layer about 400 microns thick. The surface has a fine matte texture from the plastic particles (2–50 microns), not a glossy finish.
While common for protecting large metal components, powder coating is tricky for 3D prints. Traditional metal parts handle temperatures up to 200°C, but most 3D printed plastics have lower temperature resistance, limiting its use. When possible, it’s efficient for batch production with uniform surfaces, though cavities are hard to treat.
Property Changing Post-Processing: Transforming Molecules for Better Performance
Property changing post-processing doesn’t remove or add material—it redistributes the molecules of a 3D print, using thermal and chemical treatments to create smoother, stronger parts.
Local Melting
Difficulty: Niedrig | Smoothness: Medium
Local melting is the quick fix for surface scratches from damage, support removal, or abrasive post-processing like sanding. Dark-colored prints often show rough surfaces as a whitish color, but a heat gun set to high heat can fix that. Just pass hot air over the area, keeping the gun 10–20 cm away, and within seconds, the surface melts to match the original print quality.
It also removes strings from printing—same method melts and shrinks them. Large strings might leave small remnants, but they’re easy to brush or clip off. This method only works for light surface roughness, not deep scratches, and it can deform parts if you heat an area too long. Sweep hot air across the surface for several seconds for best results, and save it for small defects, not overall smoothing.
Glühen
Difficulty: Medium | Smoothness: Low to Medium
Annealing is like a molecular reset button for your 3D print. It heats the print to reorganize its molecular structure, resulting in stronger parts less prone to warping. Untreated 3D prints have an amorphous (unorganized) molecular structure, making them weaker. Extruded plastic cools quickly and unevenly during printing, causing internal stresses—especially between layers—that make parts prone to breaking.
To strengthen at the molecular level, heat the part to its glass transition temperature (below its melting point). This lets molecules redistribute into a semi-crystalline structure without melting and deforming the part. Glass transition and melting temperatures vary by material, so you need expertise to get the temperature and timing right. Note that 3D prints shrink during annealing, but you can correct this by increasing the original printing dimensions.
Vapor Smoothing
Difficulty: Hoch | Smoothness: Sehr hoch
Vapor smoothing is a chemical magic trick for 3D prints. Parts are exposed to vaporized solvents in an enclosed chamber, and like chemical dipping, you need the right solvent for your print material. The solvent cloud dissolves the surface, and surface tension redistributes the dissolved material for a smoother finish—unlike dipping, no material is removed.
Solvents can be heated to a gas or vaporized by ultrasonic misting. Timing is critical: too short, and it’s not smooth enough; too long, and the part deforms or becomes brittle. Most solvents are caustic and combustible, requiring extreme caution, proper containment, and disposal—only qualified persons should handle them.
Many vapor smoothing machines are available for different solvents and materials, making the process automated and safer, but most can only treat smaller parts due to chamber size limits.
Perspektive der Yigu -Technologie
Bei Yigu Technology, we believe 3D printing post-processing is the bridge between prototyping and production. Each process, from sanding to vapor smoothing, addresses unique part needs. We advocate matching techniques to material and function—subtractive for precision, additive for strength, property changing for performance. Mastering these processes unlocks 3D printing’s full potential, delivering parts that look great and perform reliably.
