Rigid Clear FAST
Grade
FAST = fast-set thin-wall casting clear
For quick-turn silicone-mold casting of thin clear parts where demold in under an hour is needed.
Values for the FAST condition
Other Rigid Clear grades and fills
Rigid Clear is listed in 6 conditions; see the grade overview at Rigid Clear.
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 |
FASTThis page 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 |
What is Rigid Clear FAST?
Rigid Clear FAST is Rigid Clear in the FAST grade — for quick-turn silicone-mold casting of thin clear parts where demold in under an hour is needed. Rigid Clear FAST has a yield strength of 33 MPa (4.79 ksi) and a tensile strength of 35 MPa (5.08 ksi) — weaker than 78% of polyurethane grades. Elongation at break is 8% and the elastic modulus is 1.9 GPa (0.276 Msi). Rigid Clear FAST 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).
Advantages
- Tough — resists crack growth — 2.1 MPa·√m (1.91 ksi·√in), better than 120% of polyurethane grades
- 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
Limitations
- Low strength — 33 MPa (4.79 ksi), worse than 78% of polyurethane grades
- Limited ductility — 8%, worse than 76% of polyurethane grades
Rigid Clear FAST properties
Typical room-temperature values for Rigid Clear FAST; 24 are specific to this condition. Other listed values are Rigid Clear reference data and may not represent this condition. Bars are the position among polyurethane grades.
Physical6
Rigid Clear FAST 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 FAST has a yield strength of 33 MPa (4.79 ksi) and a tensile strength of 35 MPa (5.08 ksi) — weaker than 78% of polyurethane grades. Elongation at break is 8% and the elastic modulus is 1.9 GPa (0.276 Msi).
Thermal11
Rigid Clear FAST is rated for continuous service to 70°C (158 °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 FAST 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 (70/100), worse than 74% of polyurethane grades. UV resistance is fair.
Sustainability4
Producing a kilogram of Rigid Clear FAST 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 FAST's machinability is good (66/100, better than 71% of polyurethane grades); weldability not recommended (5/100); formability not recommended (10/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Rigid Clear FAST
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.
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.
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) | — |
Rigid Clear FAST — frequently asked
What is Rigid Clear FAST used for?
Rigid Clear FAST 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 FAST?
Rigid Clear FAST has a typical yield strength of 33 MPa (4.79 ksi) and a tensile strength of 35 MPa (5.08 ksi) — weaker than 78% of polyurethane grades. Strength varies by condition: see the 6 listed tempers.
Is Rigid Clear FAST easy to machine?
Reasonably — machinability is rated good (66/100, better than 71% 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 FAST 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 FAST?
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 FAST 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 FAST?
Rigid Clear FAST is rated for continuous use to about 70°C (158 °F), and briefly to 105°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in Rigid Clear FAST?
Yes — Rigid Clear FAST 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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.