SLA 3D Printing: The Complete Guide to Stereolithography

What Is SLA?

Stereolithography (SLA) is the oldest industrial 3D printing process — invented in the 1980s by Chuck Hull. A UV laser cures a liquid photopolymer resin layer by layer, producing parts with exceptional detail accuracy.

How SLA Works

1. A build platform submerges into a resin bath
2. A UV laser exposes the top layer of resin and cures it precisely
3. The platform lifts by one layer height (typically 0.025–0.1 mm)
4. The process repeats until the part is complete
5. After printing, the part is washed and post-cured in a UV oven

Technical Characteristics

• Layer height: 0.025–0.1 mm (significantly finer than FDM)
• Surface quality: Very smooth, barely visible layer lines
• Dimensional accuracy: ±0.1–0.2 mm
• Build volume: Depending on printer, up to 300 × 335 × 200 mm

Materials

SLA resins come in many variants:

• Standard resin: Affordable, for prototypes and visualizations
• ABS-like resin: Tough and impact resistant for functional prototypes
• Flexible resin: Rubber-like properties
• Dental/medical resin: Biocompatible and sterilizable
• Castable resin: Burn-out capable for jewelry casting

Advantages of SLA

• Excellent surface quality directly from the printer
• Very fine details and sharp edges
• Wide material selection with specific properties
• Ideal for jewelry, dental, figurines, and precision prototypes

Limitations of SLA

• Resins are UV-sensitive — parts yellow and become brittle with prolonged sun exposure
• Post-processing required (washing, post-curing)
• Higher material costs than FDM filaments
• Toxic resin fumes require safety precautions

SLA vs. FDM — When to Use Which?

For parts where surface aesthetics and detail fidelity are critical, SLA is the right choice.