PLA and standard resin are the default materials for the two most common kinds of desktop printer. PLA is melted and laid down in lines by a filament (FFF) printer; resin is a liquid photopolymer hardened layer by layer with light. The choice is as much about workflow as about the material. A filament print needs support removal and little else, while a resin print goes through washing and curing and involves liquid chemicals at several steps.
This page compares Polymaker PolyLite PLA with Formlabs Grey Resin V5, a general-purpose resin for Form 4 series printers. Both suppliers publish full data sheets, but Polymaker uses ISO test methods and Formlabs uses ASTM methods, so side-by-side numbers are indicative rather than exact. Other general-purpose resins have their own data sheets and post-processing instructions, and they should be followed for the bottle you actually use.
PLA and General-purpose photopolymer resin side by side
| Property | PLA | General-purpose photopolymer resin |
|---|---|---|
| How it prints | Melted filament; 190–230 °C nozzle, 25–60 °C bed (PolyLite PLA) | Liquid resin cured by light; Formlabs' data uses a Form 4 at 100 µm layers |
| Ultimate tensile strength | 52.3 MPa X-Y / 40.5 MPa Z (ISO 527) | 62 MPa post-cured at 60 °C; 54 MPa after a 5-minute room-temperature cure; 46 MPa green (ASTM D638) |
| Tensile modulus | 3426.9 MPa X-Y (ISO 527) | 2675 MPa post-cured at 60 °C (ASTM D638) |
| Elongation at break | 6.3% X-Y / 1.8% Z | 13% post-cured at 60 °C; 22% green |
| Flexural strength / modulus | 86.9 / 3230.9 MPa X-Y (ISO 178) | 103 / 2750 MPa post-cured at 60 °C (ASTM D790) |
| Impact (different tests) | Notched Charpy 3.3 kJ/m² X-Y (ISO 179) | Notched Izod 32 J/m post-cured at 60 °C (Formlabs lists ASTM D4812) |
| Heat deflection (1.8 / 0.45 MPa) | 58 °C / 60 °C (ISO 75) | 59 °C / 71 °C post-cured at 60 °C; 54 °C / 62 °C green (ASTM D648) |
| Thinnest typical wall | About 0.8 mm for FDM printers (Formlabs) | As thin as 0.2 mm on a Form 4 (Formlabs) |
| After printing | Remove supports; Prusa: wet sand, and chemical smoothing only in lab conditions | Wash 5 min in IPA (Form Wash), let dry, post-cure, then remove supports |
| Post-cure | Not stated | Form Cure V2: 1 min without heat by default; 5 min at 60 °C for a full cure |
| Air quality | NIOSH: filament printers release ultrafine particles and gases; PLA generally fewer particles than ABS | NIOSH: printing, IPA washing and curing release particles and gases; Formlabs: at least three air changes per hour |
| Skin protection | Not stated | NIOSH: uncured resin can cause asthma or dermatitis; gloves rated for acrylates and IPA. Formlabs: nitrile or neoprene |
| Waste | Not stated | Formlabs: never pour liquid resin or used solvent down a drain; cure small amounts of resin before discarding |
| Outdoor use | Prusa: degrades under UV light; not suitable for outdoor use | Not stated for Grey Resin V5 |
PLA values come from Polymaker's PolyLite PLA data sheet (ISO methods, 100% infill specimens). Resin values come from Formlabs' Grey Resin V5 data sheet (ASTM methods, Form 4 at 100 µm, washed 5 minutes in IPA, post-cured 15 minutes at 60 °C unless noted). Workflow and safety guidance comes from Formlabs support articles, NIOSH and Prusa.
Strength and stiffness
The two materials are closer than their reputations suggest. Post-cured at 60 °C, Grey Resin V5 reaches 62 MPa ultimate tensile strength and 13% elongation in Formlabs' tests. PolyLite PLA reaches 52.3 MPa and 6.3% in the print plane, but it is the stiffer material, with a tensile modulus of 3,427 MPa against 2,675 MPa. Because the suppliers use different standards (ISO 527 for Polymaker, ASTM D638 for Formlabs), small gaps should not decide the choice.
Direction matters more for PLA. Polymaker's Z-direction tensile strength for PolyLite PLA is 40.5 MPa, against 52.3 MPa in the X-Y plane, because filament layers are bonded less strongly than the lines within them. Formlabs describes SLA parts as highly isotropic, meaning similar in every direction. That is a vendor claim, and Formlabs' Grey data sheet reports one value per property rather than per direction.
Heat
Neither is a heat-resistant material. Polymaker lists 58 °C heat deflection at 1.8 MPa for PolyLite PLA, and Prusa says PLA softens and deforms above about 60 °C. Formlabs lists 59 °C at 1.8 MPa and 71 °C at 0.45 MPa for Grey Resin V5 after a 15-minute, 60 °C post-cure.
For the resin, the cure changes the result. Green parts, washed but not cured, and parts cured for 5 minutes at room temperature both measure 54 °C and 62 °C at the same two loads. If heat matters, a full heated cure is part of the recipe, not an optional extra.
Detail and surface finish
Resin's main advantage is resolution. Formlabs says FDM printers can typically make walls about 0.8 mm thick, while a Form 4 can make walls as thin as 0.2 mm, and that FDM parts often show clearly defined layer lines. Formlabs describes Grey Resin V5 as matte and able to capture fine features. These are claims from a company that sells resin printers, so a test print of your own feature sizes is the fair check.
Prusa counts good detail among PLA's strengths and recommends it for concept models, figures and prototypes. Finishing PLA is the harder part: Prusa advises wet sanding, and says chemical smoothing needs dangerous solvents that belong in a lab.
Washing, curing and waste
Every resin print leaves the printer coated in liquid resin. Formlabs lists a 5-minute IPA wash in Form Wash for Grey Resin V5. Its finishing guide says parts must be fully dry before post-curing, that IPA needs at least 30 minutes to evaporate, and that supports come off after curing because unsupported parts can warp under light and heat. In Form Cure V2, Formlabs' default for Grey V5 is 1 minute without heat, with 5 minutes at 60 °C listed as a full cure.
Formlabs treats post-curing as optional for standard resins but needed for other resin types. Waste needs a plan too: Formlabs says liquid resin and resin-laden solvent must never go down a drain or into household trash, and suggests curing small amounts of resin in sunlight before disposal where no chemical waste service is available.
Ventilation and skin protection
Both kinds of printer need fresh air. NIOSH says filament printers release very small particles and gases, that PLA generally releases fewer particles than ABS, and that the printer belongs in a well-ventilated space away from people. For resin printers, NIOSH says uncured resin contains acrylates that can cause asthma or dermatitis, and that IPA washing raises concerns about lung irritation and dermatitis.
NIOSH recommends gloves that protect against acrylates and IPA, changed often, plus a lab coat and eye protection rated for UV light. Formlabs recommends nitrile or neoprene gloves, safety glasses, and a room with at least three full air changes per hour, and advises against running printers in closed, unventilated spaces. IPA vapor is flammable, so keep containers closed and away from ignition sources.
Which should you choose?
Choose PLA if…
- You want a part that is ready once supports are off, with no solvent or curing step.
- You print in a shared room where handling liquid resin and IPA is impractical.
- Stiffness matters more than stretch, given PolyLite PLA's higher tensile modulus.
- You want the low-effort material Prusa describes as easy to print and suitable for beginners.
Choose General-purpose photopolymer resin if…
- The part has fine features or thin walls, where Formlabs cites 0.2 mm walls on a Form 4.
- A smooth, matte surface matters more than a short workflow.
- You have a ventilated space, the right gloves, and a plan for resin and solvent waste.
- The part should behave similarly in every direction, which Formlabs claims for SLA parts.
Common questions
Is resin stronger than PLA?
It depends on the property. Post-cured at 60 °C, Formlabs Grey Resin V5 has 62 MPa tensile strength against 52.3 MPa in-plane for Polymaker PolyLite PLA, and stretches further before breaking. PLA is stiffer. The suppliers use different test standards, so treat the comparison as approximate.
Do I have to post-cure standard resin?
Formlabs describes post-curing as optional for standard resins. Its data show why you might cure anyway: Grey Resin V5's heat deflection at 0.45 MPa rises from 62 °C to 71 °C, and tensile strength from 54 MPa to 62 MPa, with a 15-minute cure at 60 °C instead of a 5-minute cure at room temperature.
Is resin printing safe at home?
NIOSH says uncured resin can cause asthma or dermatitis and recommends ventilation, gloves that resist acrylates and IPA, and eye protection. Formlabs recommends at least three air changes per hour. Filament printers also release particles and gases, so NIOSH advises ventilation for both. Always follow the resin's safety data sheet.
Sources
- PolyLite PLA technical data sheet Polymaker · Checked 2026-11-02
- Grey Resin V5 product page Formlabs · Checked 2026-11-02
- Grey Resin V5 technical data sheet Formlabs · Checked 2026-11-02
- Form Wash/Form Wash L time settings Formlabs · Checked 2026-11-02
- Form Cure V2 time and temperature settings Formlabs · Checked 2026-11-02
- FDM vs. SLA vs. SLS: 3D printing technology comparison Formlabs · Checked 2026-11-02
- PLA Prusa Research · Checked 2026-10-15
- SLA basic finishing steps Formlabs · Checked 2026-10-15
- Safety with Formlabs SLA products Formlabs · Checked 2026-10-15
- Disposing of resin Formlabs · Checked 2026-10-15
- Safe 3-D Printing CDC / NIOSH · Checked 2026-10-15
- Safe Desktop Vat Photopolymerization 3-D Printing CDC / NIOSH · Checked 2026-10-15
This comparison summarizes the cited documentation; it is not a lab test. Properties vary by brand, grade, print settings and orientation, so check the data sheet for the exact product you buy.