Resin printing offers high-resolution prints with exceptional detail, but the prints often require post-processing to achieve their full potential. Post-processing not only improves the surface finish but also enhances the strength, durability, and overall appearance of the printed model. This process involves several steps, including cleaning, curing, and finishing techniques.
In this guide, we’ll explore the best practices for post-processing resin prints, providing tips to help you achieve high-quality results.
1. Cleaning the Print
Why It’s Important:
After printing, resin prints are covered in uncured resin, which needs to be cleaned off before curing. If uncured resin remains on the print, it can cause sticky surfaces and weaken the final print.
How to Clean:
- Isopropyl Alcohol (IPA): Use 90%-99% isopropyl alcohol to clean your prints. Place your print in a container with enough IPA to submerge the model and gently agitate it. For better results, use an ultrasonic cleaner to remove resin more efficiently.
- Clean with Brushes: For small details or hard-to-reach areas, use soft brushes to scrub the print gently while submerged in IPA. Be cautious not to scratch the surface.
- Double-Check for Residue: After the first clean, visually inspect your print for any residual uncured resin. If necessary, rinse the print again in fresh IPA.
Tips:
- Use a Separate Container: Avoid reusing the same IPA container for multiple prints, as it becomes saturated with resin and loses its effectiveness.
- Avoid Overhandling: Always wear gloves when handling prints to avoid getting oils from your skin on the surface.
2. Drying the Print
Why It’s Important:
After cleaning, your print should be dried thoroughly before curing. If there is any IPA residue or moisture left, it can interfere with the curing process and lead to poor results.
How to Dry:
- Air Dry: Allow the print to air dry in a well-ventilated area for a few hours or until you’re sure all IPA has evaporated. Be sure to place the print on a non-stick surface to avoid any contamination.
- Use a Compressed Air Can: To speed up the drying process, you can use a can of compressed air to blow off excess IPA or moisture from the print.
- Drying Station: Some users set up dedicated drying stations, such as a heated drying box or desiccant containers, to ensure prints are dry before curing.
Tips:
- Avoid Using Heat: Avoid drying the prints with heat sources like hairdryers, as excessive heat can distort the resin or soften the print.
3. Curing the Print
Why It’s Important:
Curing is the process of exposing the resin print to UV light to harden and solidify the material. This step is critical for ensuring the final print has the desired strength, durability, and surface finish.
How to Cure:
- Use a UV Curing Station: A UV curing station or chamber is the most efficient way to cure your resin prints evenly. Place the print inside the station and let it cure for the recommended time (usually 3-10 minutes depending on the print size and resin type).
- Curing with Sunlight: You can also use direct sunlight to cure your prints, but be mindful of the temperature and exposure time. Direct sunlight can over-cure or cause uneven curing if not monitored carefully.
- Turn the Print Regularly: If using a stationary UV light source, rotate the print every few minutes to ensure uniform curing. This will help avoid any areas that remain uncured or improperly hardened.
Tips:
- Avoid Over-Curing: Over-curing can cause brittleness and deformation, especially in fine details. Follow the resin manufacturer’s curing time guidelines to avoid overexposure to UV light.
4. Post-Curing for Strength and Durability
Why It’s Important:
While initial curing hardens the resin, additional post-curing can enhance the strength, heat resistance, and overall performance of your print, especially for functional or high-stress parts.
How to Post-Cure:
- Longer Curing Time: After the initial cure, expose the print to UV light for a longer duration to increase its strength. This is especially useful for functional prints that require high durability.
- UV Curing in Rotating Stations: Some advanced curing stations have rotating functions to ensure all angles of the print receive equal exposure, leading to a more robust final result.
5. Removing Support Structures
Why It’s Important:
Most resin prints require support structures to maintain the geometry during printing. These supports can leave marks or scarring on the print, so proper removal is necessary for a smooth and clean surface.
How to Remove Supports:
- Cutting Tools: Use side cutters or pliers to carefully remove the support structures. Work slowly to avoid damaging the print’s surface.
- Sanding: After removing the supports, you may notice small marks or nubs left on the print. Use sandpaper to smooth out the surface. Start with a lower grit (200-400) and progress to a finer grit (800-1200) for a smooth finish.
- Heat for Easier Removal: If the supports are tough to remove, you can heat the print slightly using a heat gun to soften the resin and make support removal easier.
Tips:
- Support Placement: When designing your print, ensure that support placement is optimal. Minimize the number of supports needed by using smart orientations or by adding custom support structures to prevent excessive scarring.
- Support Mark Cleanup: After support removal, be sure to clean up any surface marks left from the supports. A thorough sanding and polishing process can help restore a smooth surface.
6. Sanding and Smoothing the Print
Why It’s Important:
Sanding and smoothing resin prints give them a more polished, professional look, especially for visible parts or intricate details. This step is also important for achieving a smooth surface in preparation for painting or finishing.
How to Sand:
- Wet Sanding: Wet sanding helps reduce the amount of dust and heat that can build up, preventing surface warping. Use water to keep the sandpaper clean and to cool down the surface.
- Start with Coarse Grit: Begin sanding with a coarse grit sandpaper (100-200) and gradually move to finer grits (up to 2000 or higher) for a smooth finish.
- Polishing: After sanding, use a polishing compound or a rotary tool to buff the surface to a high-gloss finish.
Tips:
- Be Gentle with Fine Details: For prints with intricate details or small features, take extra care not to over-sand or damage fine details.
- Work Slowly: Sanding resin prints can be time-consuming, but it’s important to work slowly to avoid damaging or distorting the shape.
7. Painting and Finishing
Why It’s Important:
Once the print is cleaned, cured, and sanded, you may want to add color or other finishing touches. Proper painting techniques can make your resin prints look professional and add an extra layer of customization.
How to Paint:
- Prime the Surface: Apply a primer to help the paint adhere better to the resin surface. Use a spray primer designed for plastic or resin models.
- Use Appropriate Paints: Choose paints that are compatible with resin. Acrylic paints are generally a good option for resin prints.
- Airbrushing or Brush Painting: For smooth, even coverage, airbrushing is the best technique. However, if you’re using a brush, make sure to apply thin layers to avoid visible brush strokes.
Tips:
- Add Details: After painting, you can enhance the details by adding weathering effects, dry brushing, or using washes for more depth and realism.
- Clear Coat for Protection: After painting, apply a clear coat (matte, satin, or glossy) to protect the paint and provide a consistent finish.
Conclusion
Post-processing resin prints is a crucial step to achieving professional-quality results. The process involves cleaning, curing, sanding, and painting, each step contributing to the overall strength, appearance, and finish of the print. By following these best practices, you can significantly improve the quality and durability of your resin prints, ensuring that they meet your expectations, whether for display or functional use.
Remember to clean and cure properly, remove supports carefully, and consider additional sanding and painting to achieve a polished final product.