SLA (stereolithography) 3D printing uses light to cure liquid resin into solid layers, producing smooth surfaces and detailed parts with excellent accuracy. It’s ideal for engineering prototypes, dental models, and high-resolution components.

Formlabs’ Form 4 and Form 4L printers use a next-generation Low Force Display (LFD) print engine designed for speed, precision, and reliability. In this guide, we’ll walk through how to prepare, print, and post-process parts using these and other SLA resin printers.

1. Preparing Your Workspace

Set up a clean, stable, and ventilated workspace before printing.

  • Environment: Keep the area dust-free and between 18–28 °C for consistent results.
  • Safety: Wear nitrile gloves and safety glasses when handling resin or isopropyl alcohol.
  • Tank and optics: Inspect the resin tank film for scratches, cured debris, or clouding, and clean the optics if needed.
  • Power: Use a stable power source or UPS for long prints.

Form 4 and 4L users can review Formlabs’ Best Practices for Printing with Form 4 Generation Printers for tank handling and maintenance guidelines.

2. Preparing Your Model

Accurate prints start with a properly prepared model.

  • File integrity: Export watertight STL or OBJ files with no mesh errors.
  • Wall thickness: Follow Formlabs’ design specifications for minimum walls and features.
  • Hollowing and drainage: Reduce resin use and suction forces by hollowing thicker parts and adding drain holes.
  • Orientation: Tilt flat surfaces 30–60° to minimize visible layers and peel stress.
  • Supports: Use enough supports to secure overhangs while avoiding critical surfaces.

Proper orientation and support placement prevent print failures and improve surface finish, especially for larger builds on the Form 4L.

3. Slicing and Print Settings

Use slicing software such as Formlabs PreForm to prepare your file for printing.

  • Layer height: 25–50 µm for fine detail, 100 µm for faster prints.
  • Supports: Adjust density and touchpoint size for balance between strength and easy removal.
  • Resin mixing: Stir or gently shake resin before loading to ensure even pigmentation.
  • Temperature: Warm resin (if supported) for better layer bonding and flow.

The Form 4’s LFD engine and Release Texture film reduce peel forces, allowing faster prints without sacrificing quality.

4. Printing

  • Resin check: Make sure the tank is filled with the correct resin and clear of cured bits.
  • Start print: The printer automatically calibrates, checks resin level, and begins exposure.
  • Monitor early layers: Watch the first 10–20 layers for adhesion and even curing.
  • Avoid interruptions: Keep the cover closed during printing to protect optics and maintain temperature.

Handle the Form 4 and 4L’s flexible-film resin tanks carefully to prevent deformation.

5. Post-Processing

Once printing is complete, the part must be cleaned, cured, and finished.

Wash

  • Remove the part from the build plate using the provided scraper.
  • Wash thoroughly in isopropyl alcohol (IPA) or TPM, ideally using an automated wash station.
  • Rinse twice for best results, then allow parts to dry completely.

Support Removal

  • Remove supports before or after curing depending on resin stiffness.
  • Use flush cutters and sanding tools to smooth any marks.

Cure

  • Post-cure with UV and heat to reach full strength and accuracy.
  • Avoid over-curing, which can cause brittleness or warping.

Finish

  • Wet-sand or polish surfaces as needed.

Apply UV-resistant coatings if parts will be used outdoors or under bright light.

6. Troubleshooting and Maintenance

Layers separating
Common cause: Underexposure, dirty film, cold resin
Solution: Warm resin, clean film, verify exposure

Warping
Common cause: Too few supports or small base
Solution: Add supports, increase raft size

Blurred details
Common cause: Pigment settling or low exposure
Solution: Mix resin, increase exposure slightly

Surface marks
Common cause: Large touchpoints or flat orientation
Solution: Reduce touchpoint size, reorient part

Regularly replace the resin tank film and clean optics to maintain consistent performance.

7. Tips for Reliable SLA Printing

  1. Keep resin mixed and warm before every print.
  2. Inspect the tank before each job for debris or clouding.
  3. Angle visible surfaces to reduce layer lines.
  4. Space out parts to balance peel forces.

Log print settings and outcomes to refine results over time.

Start Printing with Confidence

SLA resin 3D printing produces unmatched surface finish and precision when each step is handled carefully. The Formlabs Form 4 and Form 4L make the process faster and more dependable with advanced light control and intelligent hardware design.

With proper preparation, orientation, and post-processing, you can consistently produce professional-grade parts ready for prototypes, production components, and everything in between.