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Additive Manufacturing Processes Using Liquid Photopolymer Resin and UV Curing (SLA)

Additive Manufacturing Processes Using Liquid Photopolymer Resin and UV Curing (SLA)

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Nov 3, 2026

The additive manufacturing process that uses a liquid photopolymer resin and a UV light source to cure/solidify material layer-by-layer is Stereo Lithography (SLA) (a type of vat photopolymerization). SLA selectively cures regions of a vat of liquid UV-curable resin using UV light (often described as a UV laser), building up the part one layer at a time. 2

SLA differs from the other options because:

  • FDM uses heated thermoplastic filament, not liquid photopolymer + UV curing.
  • SLS uses a powder bed and a laser to sinter/fuse powder particles, not liquid photopolymer resin.
  • DED is a directed energy deposition approach that fuses material being deposited using focused energy; feedstock is typically powder or wire, not a liquid photopolymer vat + UV curing.

Footnotes

  1. What is SLA printing? The original resin 3D print method | Protolabs Network - SLA as vat photopolymerization using UV light (UV laser) to cure liquid photopolymer resin. ↩

  2. What is Vat Photopolymerization? Understanding the 3D Printing Process - Defines vat photopolymerization as curing liquid photopolymer resin layer-by-layer using typically UV light. ↩

  3. Fused filament fabrication - Wikipedia - Describes fused filament fabrication (FDM) as using continuous thermoplastic filament deposited by a heated extruder. ↩

  4. Selective Laser Sintering (SLS) | EOS GmbH - Explains SLS as powder bed fusion using a high-powered laser to selectively fuse powdered materials layer-by-layer. ↩

  5. Wirefeed Additive Manufacturing vs. Powder Methods | Sciaky - Describes DED using focused energy to fuse materials; powder or wire feedstock can be utilized. ↩

How Stereolithography (SLA) Resin 3D Printing Works (UV Curing)

Correct Choice: (ii) Stereo Lithography (SLA)

SLA is an additive manufacturing method in the family of vat photopolymerization, where a vat of liquid photopolymer resin is exposed to UV light to selectively solidify material into a 3D object. 2

Key idea:

  • A 3D model is sliced into layers.
  • The printer exposes the resin to UV light to cure a layer.
  • The build repeats until the full part is formed. 2

Vat photopolymerization Photopolymer UV curing Layer-by-layer build

Footnotes

  1. What is SLA printing? The original resin 3D print method | Protolabs Network - SLA as vat photopolymerization using UV light (UV laser) to cure liquid photopolymer resin. ↩

  2. What is Vat Photopolymerization? Understanding the 3D Printing Process - Defines vat photopolymerization as curing liquid photopolymer resin layer-by-layer using typically UV light. ↩ ↩2

  3. What is Stereolithography (SLA) 3D Printing? | Markforged - Explains SLA curing liquid photopolymer resin layer-by-layer. ↩

Which Process Uses Liquid Photopolymer Resin + UV Curing?

Binary alignment to the stated material/energy pathway (high = strong match).

How SLA Creates Parts Using Liquid Resin + UV Light

  1. 1
    Step 1

    A slicing workflow converts the CAD geometry into layer instructions (toolpaths) for the printer.

  2. 2
    Step 2

    The build starts in a vat containing liquid UV-curable photopolymer resin.

  3. 3
    Step 3

    A UV light source (often described as a UV laser in SLA) selectively cures the resin in the shape of the current layer.

  4. 4
    Step 4

    Cured resin solidifies and bonds to the previously cured layer (or build platform at the start).

  5. 5
    Step 5

    The platform moves by one layer thickness and the next UV-cured layer is formed until completion.

  6. 6
    Step 6

    After printing, parts typically require washing/removal of excess uncured resin and additional curing steps (process-dependent).

Distinguishing the Other Options (Why They Are Not the UV-Resin Vat Process)

(i) FDM (Fused Deposition Modeling)

FDM builds parts by extruding heated thermoplastic filament through a heated nozzle, depositing it in a programmed path, then solidifying as it cools—this is material extrusion, not UV curing of liquid resin. 2

Thermoplastic filament Material extrusion Nozzle heating Layer adhesion

(iii) SLS (Selective Laser Sintering)

SLS uses a powder bed and a high-powered laser to selectively sinter (bind/fuse) powdered material layer-by-layer. Because it relies on powders rather than a vat of liquid photopolymer, it is not the UV-resin curing process described in the question. 2

Powder bed Sintering Laser scanning Layer-wise powder deposition

(iv) DED (Direct Energy Deposition)

DED is a directed energy deposition approach where focused energy (laser/electron beam, depending on system) fuses material as it is being deposited; typical feedstock forms include powder or wire, rather than liquid photopolymer in a UV-curing vat. 2

Directed energy deposition Powder/wire feedstock Focused energy Melt pool

Footnotes

  1. Fused filament fabrication - Wikipedia - Describes fused filament fabrication (FDM) as using continuous thermoplastic filament deposited by a heated extruder. ↩

  2. What is FDM (fused deposition modeling) 3D printing? | Protolabs Network - States printer heats thermoplastic filament and deposits it layer-by-layer; layers fuse as material cools. ↩

  3. Selective Laser Sintering (SLS) | EOS GmbH - Explains SLS as powder bed fusion using a high-powered laser to selectively fuse powdered materials layer-by-layer. ↩

  4. What is Selective Laser Sintering (SLS)? | Markforged - Describes SLS laying down powder and using a laser to sinter/bind particles into a solid structure. ↩

  5. Wirefeed Additive Manufacturing vs. Powder Methods | Sciaky - Describes DED using focused energy to fuse materials; powder or wire feedstock can be utilized. ↩

  6. Additive Manufacturing | Sciaky - Provides an overview of metal AM feedstock/process forms, including directed energy deposition concepts. ↩

Quick Self-Check (MCQ Logic)

Pro Tip: Match the material state first

The phrase “liquid photopolymer resin” strongly signals a vat photopolymerization process (SLA/DLP/LCD family), not powder-bed methods like SLS and not filament extrusion like FDM. 3

Footnotes

  1. What is SLA printing? The original resin 3D print method | Protolabs Network - SLA as vat photopolymerization using UV light (UV laser) to cure liquid photopolymer resin. ↩

  2. What is Vat Photopolymerization? Understanding the 3D Printing Process - Defines vat photopolymerization as curing liquid photopolymer resin layer-by-layer using typically UV light. ↩

  3. Selective Laser Sintering (SLS) | EOS GmbH - Explains SLS as powder bed fusion using a high-powered laser to selectively fuse powdered materials layer-by-layer. ↩

Common confusion: SLA vs other resin methods

SLA is often described as using a UV laser to cure resin. Other vat photopolymerization techniques (e.g., DLP/LCD) still cure liquid resin with light but differ in how the UV light pattern is generated. The key in your question is UV-curing of liquid photopolymer in a vat—i.e., SLA is the best match among the options provided. 2

Footnotes

  1. What is SLA printing? The original resin 3D print method | Protolabs Network - SLA as vat photopolymerization using UV light (UV laser) to cure liquid photopolymer resin. ↩

  2. What is Vat Photopolymerization? Understanding the 3D Printing Process - Defines vat photopolymerization as curing liquid photopolymer resin layer-by-layer using typically UV light. ↩

Where UV-Resin Curing Fits Among AM Process Families

SLA (UV-cured liquid resin)

Vat photopolymerization

Selective UV exposure cures liquid photopolymer in a resin vat layer-by-layer. 2"

Footnotes

  1. What is SLA printing? The original resin 3D print method | Protolabs Network - SLA as vat photopolymerization using UV light (UV laser) to cure liquid photopolymer resin. ↩

  2. What is Vat Photopolymerization? Understanding the 3D Printing Process - Defines vat photopolymerization as curing liquid photopolymer resin layer-by-layer using typically UV light. ↩

FDM (heated filament)

Material extrusion

Heated nozzle extrudes thermoplastic filament; deposited strands fuse and cool. 2"

Footnotes

  1. Fused filament fabrication - Wikipedia - Describes fused filament fabrication (FDM) as using continuous thermoplastic filament deposited by a heated extruder. ↩

  2. What is FDM (fused deposition modeling) 3D printing? | Protolabs Network - States printer heats thermoplastic filament and deposits it layer-by-layer; layers fuse as material cools. ↩

SLS (laser sintering)

Powder bed fusion

Laser sinters/fuses powder bed; no liquid photopolymer vat. 2"

Footnotes

  1. Selective Laser Sintering (SLS) | EOS GmbH - Explains SLS as powder bed fusion using a high-powered laser to selectively fuse powdered materials layer-by-layer. ↩

  2. What is Selective Laser Sintering (SLS)? | Markforged - Describes SLS laying down powder and using a laser to sinter/bind particles into a solid structure. ↩

DED (powder/wire melt at deposit site)

Directed energy deposition

Focused energy melts feedstock as it is deposited; typically powder/wire. 2"

Footnotes

  1. Wirefeed Additive Manufacturing vs. Powder Methods | Sciaky - Describes DED using focused energy to fuse materials; powder or wire feedstock can be utilized. ↩

  2. Additive Manufacturing | Sciaky - Provides an overview of metal AM feedstock/process forms, including directed energy deposition concepts. ↩

Knowledge Check

Question 1 of 4
Q1Single choice

Which additive manufacturing process uses a liquid photopolymer resin and a UV light source for curing and solidification?

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