Rigid Clear
Rigid Clear is a two-component (isocyanate prepolymer plus polyol) rigid transparent polyurethane casting resin that cures at room temperature to about Shore D 75–85, reaching light transmission close to acrylic with far lower shrinkage than methacrylate systems.
Rigid Clear grades and fills
Rigid Clear is supplied in 6 conditions, soft to hard.
Compare all 6 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Semi-rigid clear | Pick when thin clear snap features or drop-impact survival matter more than stiffness. | 28 | 45 | 70 Shore D | |
Fast-set thin-wall casting clear | For quick-turn silicone-mold casting of thin clear parts where demold in under an hour is needed. | 33 | 35 | 8 | 78 Shore D |
FR V-0 | Required for electrical enclosures and lighting parts needing a UL 94 V-0 rating; clarity drops to translucent. | 34 | 35 | 7 | 82 Shore D |
Additively printed rigid clear urethane photopolymer | Choose when the clear rigid part is printed directly (no tooling) and needs thermal post-cure for full properties. | 45 | 8 | 82 Shore D | |
Heat-resistant high-Tg clear | Select when parts see 100–120 °C, e.g. under-hood clear covers or parts that must survive paint bake. | 52 | 55 | 4 | 85 Shore D |
High-hardness rigid clear | Use for stiff clear panels, lenses and machined blanks where deflection must be minimal. | 55 | 5 | 85 Shore D |
Supply forms, finishes and certifications
Ways Rigid Clear is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
MED | Medical / USP Class VI, ISO 10993 tested clear | Certification |
OPT | Optical / lens-grade water clear | Grade option |
UV | Aliphatic non-yellowing UV-stabilized clear | Grade option |
STDDefault | Standard rigid clear cast | Standard supply |
What is Rigid Clear?
Rigid Clear is a two-component (isocyanate prepolymer plus polyol) rigid transparent polyurethane casting resin that cures at room temperature to about Shore D 75–85, reaching light transmission close to acrylic with far lower shrinkage than methacrylate systems. It is used for vacuum-cast prototypes in silicone tooling, clear housings, light pipes, lenses and potting, because it reacts fast, releases well and is tougher than epoxy. Limits are low heat resistance (Tg typically 60–90 °C; 65 °C and 80 °C maximum service on the default condition), yellowing of aromatic systems under UV, and moisture sensitivity that causes CO2 bubbles. As a thermoset it cannot be remelted or reprocessed. Rigid Clear has a density of 1.06 g/cm³ (0.0383 lb/in³), lighter than 86% of polyurethane grades. Its glass-transition temperature is 65°C (149 °F). Rigid Clear has a yield strength of 38 MPa (5.51 ksi) and a tensile strength of 40 MPa (5.8 ksi) — weaker than 78% of polyurethane grades. Elongation at break is 10% and the elastic modulus is 2.1 GPa (0.305 Msi).
What is Rigid Clear used for?
- Lenses
- light pipes
- fluid visualization
Advantages
- Polishes to a fine finish — 78/100, better than 88% of polyurethane grades
- Good UV / weathering resistance — 35/100, better than 83% of polyurethane grades
- Low, predictable mold shrinkage — 0.2%, better than 75% of polyurethane grades
Limitations
- Low strength — 38 MPa (5.51 ksi), worse than 78% of polyurethane grades
Rigid Clear properties
Typical room-temperature values; bars are the position among polyurethane grades.
Physical6
Rigid Clear has a density of 1.06 g/cm³ (0.0383 lb/in³), lighter than 86% of polyurethane grades. Its glass-transition temperature is 65°C (149 °F).
Mechanical15
Rigid Clear has a yield strength of 38 MPa (5.51 ksi) and a tensile strength of 40 MPa (5.8 ksi) — weaker than 78% of polyurethane grades. Elongation at break is 10% and the elastic modulus is 2.1 GPa (0.305 Msi).
Thermal11
Rigid Clear is rated for continuous service to 80°C (176 °F). It conducts heat at 0.19 W/m·K (0.11 BTU/hr·ft·°F), worse than 90% of polyurethane grades. Thermal expansion is 120 µm/m·K (66.7 µin/in·°F).
Electrical7
Rigid Clear is an electrical insulator with a dielectric strength of 19 kV/mm (482.6 V/mil) and a resistivity of 1×10¹² Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (72/100), worse than 55% of polyurethane grades. UV resistance is fair.
Sustainability4
Producing a kilogram of Rigid Clear takes about 105 MJ of energy and emits 5 kg of CO₂ — more than 64% of polyurethane grades. Typical recycled content is 0%.
Manufacturability6
Rigid Clear's machinability is good (65/100, better than 62% of polyurethane grades); weldability not recommended (5/100); formability not recommended (10/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the polyurethane family
Yield strength against density for every polyurethane grade FabDigit runs. Rigid Clear is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Rigid Clear
Is Rigid Clear easy to machine?
Machines and drills easily with sharp carbide, high speed and low feed pressure; use air blast rather than flood coolant, and expect gumming plus surface haze above ~60 °C tool contact temperature.
Can Rigid Clear be welded?
Thermoset — cannot be melt-welded; join with polyurethane or cyanoacrylate/epoxy adhesives, or cast fresh resin against a scuffed, solvent-wiped surface.
Can Rigid Clear be formed, bent or molded?
Vacuum-degas and pressure-cast (2–4 bar) into silicone or machined molds at 25 °C; dry all fillers/molds since traces of moisture cause CO2 bubbles, then post-cure 4–16 h at 60–70 °C for full Tg and clarity.
Rigid 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 |
|---|---|---|
| isocyanate component (aromatic MDI or alPart A; aliphatic types used for non-yellowing clear | 40 – 60 | 50 |
| catalyst (organometallic / amine) | 0.01 – 0.5 | 0.1 |
| UV absorber + HALSUV-stabilized grades only | 0 – 1.5 | 0.5 |
| molecular sieve / moisture scavengersuppresses CO2 bubbling | 0 – 2 | 0.5 |
| flame retardant (phosphate ester / halogFR variant only | 0 – 20 | 0 |
| polyol component (polyether or polyesterPart B; polyether improves hydrolysis resistance | ≥ 40 (balance) |
What surface finishes work on Rigid Clear?
Wet-sand 600→2000 grit and polish with plastic compound for optical clarity; accepts clear PU topcoats and vapor-polish-free hard coats, but do not use ammonia-based cleaners and expect aromatic grades to yellow without a UV clearcoat.
How much does Rigid Clear cost?
Rigid Clear is a standard-cost polyurethane ($$), cheaper than about 82% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Rigid Clear — frequently asked
What is Rigid Clear used for?
Rigid Clear is typically used for lenses, light pipes and fluid visualization. In short: water-clear rigid PU; polishable to optical clarity.
What is the yield strength of Rigid Clear?
Rigid Clear has a typical yield strength of 38 MPa (5.51 ksi) and a tensile strength of 40 MPa (5.8 ksi) — weaker than 78% of polyurethane grades. Strength varies by condition: see the 6 listed tempers.
Is Rigid Clear easy to machine?
Reasonably — machinability is rated good (65/100, better than 62% of polyurethane grades). Machines and drills easily with sharp carbide, high speed and low feed pressure; use air blast rather than flood coolant, and expect gumming plus surface haze above ~60 °C tool contact temperature.
Can Rigid Clear be welded?
Not readily — weldability is rated not recommended (5/100). Thermoset — cannot be melt-welded; join with polyurethane or cyanoacrylate/epoxy adhesives, or cast fresh resin against a scuffed, solvent-wiped surface.
What surface finishes work on Rigid Clear?
Wet-sand 600→2000 grit and polish with plastic compound for optical clarity; accepts clear PU topcoats and vapor-polish-free hard coats, but do not use ammonia-based cleaners and expect aromatic grades to yellow without a UV clearcoat.
Can Rigid Clear be formed, bent or molded?
Vacuum-degas and pressure-cast (2–4 bar) into silicone or machined molds at 25 °C; dry all fillers/molds since traces of moisture cause CO2 bubbles, then post-cure 4–16 h at 60–70 °C for full Tg and clarity.
What is the maximum service temperature of Rigid Clear?
Rigid Clear is rated for continuous use to about 80°C (176 °F), and briefly to 105°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Rigid Clear cost?
Rigid Clear is a standard-cost polyurethane ($$), cheaper than about 82% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in Rigid Clear?
Yes — Rigid Clear is available for urethane casting with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- Crystal Clear Series Water-Clear Urethane Casting Resin TDS — Smooth-On (2023)
- TC-800 / WC-Clear Rigid Optical Urethane Systems — BJB Enterprises (2022)
- Water Clear Casting Resin Technical Data — Alumilite (2022)
- Rigid / Clear DLS Photopolymer-Urethane Material Data — Carbon Inc. (2023)
- Polyurethane Handbook, 2nd ed. — Hanser (Oertel) (1994)
- ASTM D638 / D790 / D256 / D2240 / D648 — ASTM International (2022)
- CAMPUS / Ashby polymer eco-property data for PU thermosets — CAMPUS / Granta (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.