3D printing · process family

SLA / DLP / MSLA

Vat photopolymerization · SLA · DLP · MSLA · LCD

Cure a liquid resin with light, one thin layer at a time

A vat of liquid photopolymer resin is cured selectively by UV light, layer by layer. Because the light can be focused finely and each layer chemically bonds to the last, this is the way to get the smoothest surfaces and the finest detail in 3D printing — and, unusually, a nearly isotropic part. The catch is that the resins are thermosets: cross-linked, brittle, messy to handle, and not remeltable.

cure · lift · repeat
SLA / DLP / MSLA — cure a liquid resin with light, one thin layer at a time.
0.01–0.05 mm layers
Resolution
Moderate (fast on MSLA/CLIP)
Speed
$$
Cost
Good (chemical bonding)
Isotropy

How it works

  1. 1
    A build platform is lowered into a vat of liquid photopolymer.
  2. 2
    A light source cures a single layer's cross-section against the platform (or a clear film at the vat floor).
  3. 3
    The platform lifts (bottom-up) or steps down (top-down) by one layer.
  4. 4
    Fresh resin flows in and the next layer is cured, bonding to the last.
  5. 5
    The green part is washed (IPA) to remove uncured resin, then UV post-cured to reach full strength.

The machines

The variants of this family, from the hobby basics to the industrial state of the art.

Laser SLA

Pro / industrial

A UV laser spot traces each layer. The original (1986) and still the accuracy benchmark for large, fine parts.

DLP

Prosumer / pro

A digital projector flashes a whole layer at once as a pixel image — fast, resolution set by projector optics.

MSLA / LCD

Hobby / prosumer

A UV LED array shines through a masking LCD; the screen's pixels define the layer. Cheap high-resolution (mono 8K–12K LCDs) — the desktop resin standard.

CLIP / continuous

Industrial

An oxygen-permeable window keeps a 'dead zone' of uncured resin so the part is drawn up continuously, not layer-by-layer — dramatically faster (Carbon-style).

Strengths & limits

Strengths
  • Finest detail and the smoothest surface of any process
  • Nearly isotropic — layers cross-link chemically
  • Excellent for small, intricate parts
  • Wide resin range: tough, flexible, castable, high-temp, biocompatible
Limits
  • Many resins are brittle and keep curing (and embrittling) in sunlight
  • Uncured resin is messy and an irritant — needs wash + post-cure
  • Smaller build volumes; supports on nearly every part
  • Thermoset, so no remelting or recycling

Typical parts & materials

Feedstock: Liquid photopolymer resin · Thermosets — cross-linked, not remeltable.

Typical parts: Dental and jewellery masters, miniatures, hearing aids, fine functional prototypes

Commonly run in — open one for its cited properties:

Photopolymer resin (thermoset)Tough / 'ABS-like' resinCastable resinHigh-temp & ceramic-filled resin

What's new

Fast monochrome 8K/12K LCD screens made high-resolution resin printing cheap, and the resin chemistry has caught up — genuinely tough, heat-resistant and even ceramic-filled engineering resins now exist. Continuous processes (CLIP) and areal/volumetric curing chase speed without stair-stepping.

Part of the 3D printing guide. Compare the other process families, see the design rules, or browse the cited materials database.