What is the Difference Between SLA and LFS?

Formlabs Form 3+

You’ve probably already heard of SLA (stereolithography), a 3D printing process in which layers of liquid-resin are selectively cured solid with a laser.

SLA is a mature technology that offers several advantages over FFF, including speed, flexibility, and precision. However, the biggest advantage is there is no mechanical print head to restrict potential geometries.

Formlabs is the leading desktop manufacturer of SLA technology, but they discontinued usage of the traditional technology with the Form 2. Now, all Formlabs printers use LFS, a natural successor to SLA technology.

The key differences

  • LFS is faster than SLA.
  • LFS is more consistent than SLA.
  • SLA has a rigid tank, while LFS has a flexible tank.
  • LFS has a smaller laser spot size.
  • SLA has two galvanometers for X and Y positioning, directing laser light from the back of the printer to a large stationary mirror and then to the platform; LFS uses an LPU that contains a system of lenses and mirrors.

LFS delivers a better 3D printing experience

SLA has a problem with peel forces – the significant forces exerted on parts during printing makes supports difficult to remove.

LFS is a Formlabs innovation with the Form 3+ and Form 3L, which addresses the peel force challenge with a flexible resin tank and linear illumination to reduce print forces. It lets you literally pull away at the support structure, and it snaps off cleanly.

LFS supports

In January, Formlabs also launched the Build Platform 2, a flexible surface that instantly releases parts with a quick-release mechanism. This eliminates all risk of damaging parts using plastic or metal removal tools.


Smoother, more consistent parts and models


Another advantage of LFS is the closed optics engine called the Light Processing Unit (LPU). The LPU emits a crisp, clean laser spot, with a spatial filter to catch stray light and a series of mirrors, ensuring the beam is delivered perpendicular to the print plane.


The laser spot is less refined in SLA, and stray light is more evident. Under a microscope, the surface and edge quality are noticeably worse in SLA prints than in LFS prints. You can also see it with models printed in translucent materials:


LFS quality


The linear path of the laser brings out the best in fine details and gives models a smoother surface finish. The quality of LFS parts is superior to SLA parts, letting you build more complex and detailed models than ever.


LFS detail
This model was printed with LFS


When comparing the Formlabs Form 3+ with the now discontinued Form 2, the Form 3+ has more sensors across the printer to detect and maintain ideal print conditions. For example, the optical sensor detects dust.




Overall, LFS is superior to SLA in every way, so if you are looking at a Formlabs printer or SLA technology from another brand, we recommend LFS.


To find out more about LFS and SLA, request a Formlabs sample, call us on 01765 694 007, or send us an email at sales@additive-x.com. You can also book a discovery call with our Formlabs specialists Elaine Rutledge or Tammy O’Neill.


Elaine RutledgeBook a call with Elaine Book a call with Tammy