Post-processing Guide: From Print to Perfection

Post-processing is the set of techniques that transform a raw 3D print into a smooth, professional-looking product. It involves sanding through grits from 120 up to 1200, filling gaps with acrylic filler or spray filler primer in 2–3 coats, and applying final paint in thin layers from a distance of 20–30 cm.

This guide will walk you through the most important steps to take your prints to the next level.

How do you remove supports and clean a fresh print?

The first step is always careful cleaning of the model.

Removing supports: Support structures are essential for more complex models, but their removal requires patience. Use small pliers, tweezers, or a scalpel. Proceed carefully so as not to damage the model itself. Gently cut off any support remnants that cannot be broken off.
Cleaning the surface: Remove all loose pieces of plastic, "hairs" (stringing), or other minor print artifacts.

How do you sand a 3D print to a smooth surface?

Sanding is the most important, but also the most laborious, part of post-processing. The goal is to get rid of visible layers and create a perfectly smooth surface.

Start rough, finish fine: Use sandpaper with different grits. Start with coarser grit (120–200 grit) to remove the largest imperfections and gradually move to finer grits (400, 800, 1200 grit) to achieve a smooth finish. This typically means working through 4–5 stages of grit.
Wet sanding: For finer grits, soak the sandpaper in water. Water helps to remove dust, prevents clogging of the paper, and creates an even smoother surface. It is an ideal technique before painting.
Watch out for heat: Heat is generated during sanding (especially machine sanding). Materials with low heat resistance, such as PLA (which softens at ~60°C), can deform. Therefore, work with breaks and do not press too hard.

How do you fill and prime to hide layer lines?

Even the best sanding sometimes doesn't hide all gaps between layers or small holes. This is where filler and primer come in.

Acrylic filler: Easy to apply, quick-drying, and sands well. It is ideal for filling smaller gaps.
Spray filler primer: This special type of spray paint serves as a base coat and also fills microscopic scratches and unevenness. Apply a thin layer, let it dry, lightly sand it with fine sandpaper (800 grit), and repeat the process if necessary. Two to three coats of filler can work wonders on the surface.

Which glue should you use for PLA and PETG?

If you are printing a large model in parts, you will need to glue them together.

Material	Recommended adhesive	Notes
PLA	Cyanoacrylate (superglue)	Add spray activator for a stronger bond
PETG	Cyanoacrylate or epoxy	Chemical welding not possible
Large/stressed parts	Two-part epoxy	Longer cure time (min. 30 min), fills gaps

How do you paint a 3D print for a professional final look?

Painting gives your model its final color, sheen, and a protective layer.

Primer: Always start with a primer (ideally the aforementioned spray filler primer). It unifies the surface and ensures that the final paint will adhere well.
Applying paint: You will achieve the best results with spray paints. Apply them in several thin layers from a distance of 20–30 cm. Let the paint dry well between layers.
Detail work: For details, use acrylic paints and a brush.
Protective clear coat: Finally, spray everything with a clear coat (matte, semi-matte, or glossy). This protects the paint from scratches and UV radiation.

Conclusion: Patience Bears Fruit

Post-processing can be time-consuming, but the result is worth it. The ability to transform a raw print into a smooth, professional-looking object is a skill that will take your 3D printing projects to a whole new level. Whether you're making a prototype for a client, a cosplay prop, or just a model for fun, give the finishing touches the time they deserve.

Don't have time or equipment for post-processing? No problem! We can supply you with raw prints made from quality materials, ready for your own artistic finishing. Contact us and we'll discuss your project.