Clear Optical Grade
Grade
also Transparent Resin, Clear Resin
Pick when the part must transmit or guide light (lenses, light pipes, flow cells) and will be sanded/polished or vapour-clear-coated.
Values for the Optical Grade condition
Other Clear grades and fills
Clear is listed in 3 conditions; see the grade overview at Clear.
- As-Printed
- Optical Grade
- UV Resistant
Compare all 3 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
washed but not UV post-cured | Only relevant for form/fit checks or parts to be bonded before cure — green strength and heat resistance are much lower and creep is significant. | — | 38 | 12 | 70 Shore D |
Optical GradeThis page low-haze, index-controlled clear resin for light-guiding parts | Pick when the part must transmit or guide light (lenses, light pipes, flow cells) and will be sanded/polished or vapour-clear-coated. | — | 60 | 7 | 79 Shore D |
HALS/UV-absorber stabilized clear resin, reduced yellowing | Use for parts with sunlight or lamp exposure where colour stability over months matters; slightly lower initial clarity and marginally softer cure. | — | 62 | 7.5 | 78 Shore D |
What is Clear Optical Grade?
Clear Optical Grade is Clear in the Optical Grade grade — pick when the part must transmit or guide light (lenses, light pipes, flow cells) and will be sanded/polished or vapour-clear-coated. Clear Optical Grade has a yield strength of 52 MPa (7.54 ksi) and a tensile strength of 60 MPa (8.7 ksi) — stronger than 56% of polymer grades. Elongation at break is 7% and the elastic modulus is 2.6 GPa (0.377 Msi). Clear Optical Grade has a density of 1.19 g/cm³ (0.043 lb/in³), heavier than 53% of polymer grades. Its glass-transition temperature is 65°C (149 °F).
Advantages
- Polishes to a fine finish — 92/100, better than 97% of polymer grades
Limitations
- Limited formability — 5/100, worse than 95% of polymer grades
- Limited service temperature — 55°C (131 °F), worse than 91% of polymer grades
- Low fracture toughness — 0.9 MPa·√m (0.819 ksi·√in), worse than 90% of polymer grades
- Difficult to weld — 5/100, worse than 89% of polymer grades
- Needs corrosion protection — 65/100, worse than 86% of polymer grades
Clear Optical Grade properties
Typical room-temperature values for Clear Optical Grade; 12 are specific to this condition. Other listed values are Clear reference data and may not represent this condition. Bars are the position among polymer grades.
Physical6
Clear Optical Grade has a density of 1.19 g/cm³ (0.043 lb/in³), heavier than 53% of polymer grades. Its glass-transition temperature is 65°C (149 °F).
Mechanical14
Clear Optical Grade has a yield strength of 52 MPa (7.54 ksi) and a tensile strength of 60 MPa (8.7 ksi) — stronger than 56% of polymer grades. Elongation at break is 7% and the elastic modulus is 2.6 GPa (0.377 Msi).
Thermal11
Clear Optical Grade is rated for continuous service to 55°C (131 °F). It conducts heat at 0.2 W/m·K (0.116 BTU/hr·ft·°F), worse than 56% of polymer grades. Thermal expansion is 110 µm/m·K (61.1 µin/in·°F).
Electrical5
Clear Optical Grade is an electrical insulator with a dielectric strength of 15 kV/mm (381 V/mil) and a resistivity of 1×10¹² Ω·m.
Chemical & Environmental3
Corrosion resistance is good (65/100), worse than 86% of polymer grades. UV resistance is poor.
Sustainability3
Producing a kilogram of Clear Optical Grade takes about 110 MJ of energy and emits 5.5 kg of CO₂ — more than 64% of polymer grades. Typical recycled content is 0%.
Manufacturability4
Clear Optical Grade's machinability is fair (45/100, worse than 78% of polymer grades); weldability not recommended (5/100); formability not recommended (5/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Clear Optical Grade
Is Clear easy to machine?
Drill and mill with sharp carbide, high speed, light feed and air cooling; the crosslinked resin is notch-sensitive and will craze or chip if heated or clamped hard.
Can Clear be welded?
Thermoset — cannot be heat welded; join with UV-cure acrylate adhesive, cyanoacrylate or a drop of the same resin cured under a 405 nm lamp.
Can Clear be formed, bent or molded?
Vat photopolymerization only: resin 25–35 °C, 25–100 µm layers, then IPA wash (keep soak short to avoid clouding/swelling) and 30–60 min 405 nm post-cure at 60–80 °C for full properties; expect ~0.2–0.5% cure shrinkage and warping in thick solid sections.
What surface finishes work on Clear?
For clarity wet-sand 400→3000 grit then polish with plastic compound, or apply a thin clear UV/acrylic coat; avoid acetone and prolonged IPA, and add a UV-blocking topcoat if the part sees sunlight.
Clear chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| urethane acrylate / epoxy acrylate oligobackbone oligomer, sets stiffness and toughness | 30 – 60 | 45 |
| photoinitiator (TPO / BAPO / Irgacure ty385/405 nm absorbing | 0.5 – 4 | 2 |
| UV absorber / light blockercontrols cure depth; higher in UV-resistant grade with HALS | 0 – 1 | 0.2 |
| additives (defoamer, stabilizer, chain-t | 0.1 – 3 | 1 |
| acrylate / methacrylate reactive monomere.g. HDDA, TPGDA, IBOA — controls viscosity and Tg | ≥ 30 (balance) | — |
Clear Optical Grade — frequently asked
What is Clear Optical Grade used for?
Clear Optical Grade is typically used for optical prototypes, light pipes, LED diffusers and lens covers, fluidic and microfluidic test channels, sight glasses and inspection windows and transparent demonstration housings. In short: optically clear photopolymer.
What is the yield strength of Clear Optical Grade?
Clear Optical Grade has a typical yield strength of 52 MPa (7.54 ksi) and a tensile strength of 60 MPa (8.7 ksi) — stronger than 56% of polymer grades. Strength varies by condition: see the 3 listed tempers.
Is Clear Optical Grade easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 78% of polymer grades). Drill and mill with sharp carbide, high speed, light feed and air cooling; the crosslinked resin is notch-sensitive and will craze or chip if heated or clamped hard.
Can Clear Optical Grade be welded?
Not readily — weldability is rated not recommended (5/100). Thermoset — cannot be heat welded; join with UV-cure acrylate adhesive, cyanoacrylate or a drop of the same resin cured under a 405 nm lamp.
What surface finishes work on Clear Optical Grade?
For clarity wet-sand 400→3000 grit then polish with plastic compound, or apply a thin clear UV/acrylic coat; avoid acetone and prolonged IPA, and add a UV-blocking topcoat if the part sees sunlight.
Can Clear Optical Grade be formed, bent or molded?
Vat photopolymerization only: resin 25–35 °C, 25–100 µm layers, then IPA wash (keep soak short to avoid clouding/swelling) and 30–60 min 405 nm post-cure at 60–80 °C for full properties; expect ~0.2–0.5% cure shrinkage and warping in thick solid sections.
What is the maximum service temperature of Clear Optical Grade?
Clear Optical Grade is rated for continuous use to about 55°C (131 °F), and briefly to 85°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in Clear Optical Grade?
Yes — Clear Optical Grade is available for injection molding and 3D printing with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- Clear Resin photopolymer technical data sheet (SLA/LFS) — Formlabs (2023)
- ASTM D638 / D790 / D256 / D648 test methods for plastics — ASTM International (2022)
- Photopolymers: Chemistry and Properties of UV-curable acrylate systems — Wiley / SpecialChem technical literature (2019)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.