A guide to

SLA 3D printing

A guide to

SLA 3D printing

A guide to SLA 3D Printing

SLA is an acronym for Stereolithography, which is a method of 3D printing. It is one of the oldest types of 3D printing. This method can be used to produce parts for both prototyping and functional use with a wide range of utilities and properties.

While there can be several different types of SLA 3D printing the common theme is that a laser or light source irradiates specific patterns on a photosensitive resin one very thin layer at a time until an object is fully formed. This method has the ability to produce extremely fine and accurate details which allows it to be used in a vast variety of applications.

1. SLA 3D printing and its most common forms

SLA 3D printing typically is available in two versions: top-down and bottom-up. In top down arrangement, the print base is submerged below the liquid resin surface and after each layer is irradiated the base drops down a tiny fraction so that the next layer can be created. The resolution of the prints are determined by the width of the laser which explains why the detail is so good. There are some drawbacks with this method in that you typically need to use more resin volume than other photopolymer methods, and the time can be a bit longer due to the laser having to trace every layer.

orange 3D mold of SLA 3D Printing with RAHN

In bottom-up situations of SLA 3D printing, the laser is situated below a vat of photopolymer and shines through a film, or window. The build plate is held a very specific distance above the film, submerged in the resin. After each layer is irradiated, the base pulls away from the film to allow liquid resin to flow back over the window and the base is then returned, this time leaving the same gap between the window and the last layer printed. This method has benefits in that you tend to be able to use much less resin for a given build volume. Printers and parts also tend to be less expensive. The main drawbacks are that there tend to be smaller build areas available, and there is more service/troubleshooting required.

A newer version of SLA 3D printing is called mSLA or "masked" SLA. This can also be called LCD printing whereby a single light source (not a laser) is used, and an LCD screen is used to mask where irradiation is not desired. Virtually all of the other operations/mechanics are the same. One major benefit is lower cost as the light source is much less expensive, but it also tends to be faster.

2. Requirements for SLA 3D printing materials

Requirements of 3D printing resins for these methods tend to be relatively similar. Lower viscosity is better as it allows for fast and uniform recoating/refilling. Low shrinkage allows for little to no warping (which is especially important for fine details and larger structures. One aspect that needs to be considered in bottom-up printers is compatibility with the window material.


You do not want SLA 3D printing materials that will swell, cloud, or otherwise attack the window material (typically either PDMS or FEP). You obviously do not want anything to adhere to the window after curing as that can lead to delamination of layers, or other destruction of the print.

3. SLA 3D printing applications

3D printing teeth modell - SLA 3D Printing RAHN


Thanks to its unmatched accuracy and precision, and broad choice of materials, SLA 3D Printing is a very versatile, and an effective means to produce both prototypes and production pieces.

IIt’s utilized across various sectors including 3D printing in dentistry and industries like manufacturing and engineering, with its applications extending to the expansive field of 3D printing in healthcare.


4. Why choose the SLA 3D printing method?

SLA printing has become the most widely used method of 3D printing because of the smooth surface and fine details the technology provides. Its high production quality and increased productivity has made the technology a staple in the UV additive manufacturing industry. SLA 3D printing is always a smart option.

Contact RAHN to get high-quality raw materials for 3D printing resins, customised to your industry needs.

Your personal contact

Christopher Cocklan

Christopher Cocklan

3D Printing Business Development Manager EnergyCuring