What Vat Photopolymerization is

Vat Photopolymerization [2].

Vat photopolymerization, also known as stereolithography (SLA), is the process by which a liquid is cured by a light source, turning it into a solid [1]. This phenomenon became known as polymerization and was the very first industrial additive manufacturing technology [1]. A laser draws the shape of each layer into a resin-filled vat, and once it solidifies, the build platform moves to make room for the next layers. During this process, fresh resin fills the gaps.










  1. The build platform lowers down into the resin vat by the layer thickness.
  2. UV light is used to cure the resin layer by layer. The platform moves downwards as additional layers are built on top of the existing layers.
  3. In some machines, a blade moves between layers to provide a smooth resin base to build the next layer on.
  4. The model is removed after the vat is drained of resin.

Curing Process

Once the model is complete, it cures in a special chamber with additional UV light [1]. When the resin is fully cured, the model is ready for use.


This process uses plastics and polymers, and the polymers must be UV-curable.

Equipment Used Today


Vat photopolymerization is used in several markets because the materials are easily accessible [1]. The method is useful for making various consumer products, like hearing aids. The manufacturer Sonova uses SLA in the production of hearing aids to create products customized to individual clients [1]. Another industry is the shoe industry; Adidas and Nike use this technology for serial production [1].

Pros and Cons


  • High level of accuracy [1]
  • Smooth finishes [2]
  • Faster printing time
    • While many additive manufacturing processes need to trace the part pattern on each layer, Vat Polymerization can print by projecting the entire layer pattern on the liquid surface [3]
  • Models might be used more for quick displays or views of a newly modeled part [3]


  • Support structures often required [1]
  • Lengthy post-processing [1]
  • Models are still not as good in terms of impact strength and lasting durability, especially when compared to injection molded parts [3]

 Video Demonstration of the Vat Photopolymerization Process


[1] https://all3dp.com/2/main-types-additive-manufacturing/

[2] https://www.lboro.ac.uk/research/amrg/about/the7categoriesofadditivemanufacturing/vatphotopolymerisation/

[3] https://steemit.com/engineering/@djanky/vat-polymerization-pros-and-cons-or-additive-manufacturing