Rigid Clear · heat-treated state
Rigid Clear-HT
Properties of the HT condition, compared with the other Rigid Clear grades.
Select when parts see 100–120 °C, e.g. under-hood clear covers or parts that must survive paint bake.
What is Rigid Clear-HT?
Rigid Clear-HT is Rigid Clear heat treated to HT — select when parts see 100–120 °C, e.g. under-hood clear covers or parts that must survive paint bake. Rigid Clear-HT has a yield strength of 38 MPa (5.51 ksi) and a tensile strength of 55 MPa (7.98 ksi) — weaker than 80% of polyurethane grades. Elongation at break is 4% and the elastic modulus is 2.1 GPa (0.305 Msi). Rigid Clear-HT has a density of 1.06 g/cm³ (0.0383 lb/in³), lighter than 83% of polyurethane grades. Its glass-transition temperature is 110°C (230 °F). STD is the default condition FabDigit quotes; HT is available on request or by drawing note.
Advantages
- High service temperature — 120°C (248 °F), better than 100% of polyurethane grades
- Polishes to a fine finish — 78/100, better than 88% of polyurethane grades
- Good UV / weathering resistance — 35/100, better than 85% of polyurethane grades
- Low, predictable mold shrinkage — 0.2%, better than 77% of polyurethane grades
Limitations
- Limited ductility — 4%, worse than 96% of polyurethane grades
- Low strength — 38 MPa (5.51 ksi), worse than 80% of polyurethane grades
Rigid Clear-HT properties
Typical room-temperature values for Rigid Clear-HT — 9 properties are specific to this condition; the rest are grade-level values shared by every Rigid Clear grade. Each bar shows where the value sits among the polyurethane grades in FabDigit's library — further right is higher.
Physical6
Rigid Clear-HT has a density of 1.06 g/cm³ (0.0383 lb/in³), lighter than 83% of polyurethane grades. Its glass-transition temperature is 110°C (230 °F).
Mechanical15
Rigid Clear-HT has a yield strength of 38 MPa (5.51 ksi) and a tensile strength of 55 MPa (7.98 ksi) — weaker than 80% of polyurethane grades. Elongation at break is 4% and the elastic modulus is 2.1 GPa (0.305 Msi).
Thermal11
Rigid Clear-HT is rated for continuous service to 120°C (248 °F). It conducts heat at 0.19 W/m·K (0.11 BTU/hr·ft·°F), worse than 87% of polyurethane grades. Thermal expansion is 120 µm/m·K (66.7 µin/in·°F).
Electrical7
Rigid Clear-HT 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 52% of polyurethane grades. UV resistance is fair.
Sustainability4
Producing a kilogram of Rigid Clear-HT takes about 105 MJ of energy and emits 5 kg of CO₂ — more than 63% of polyurethane grades. Typical recycled content is 0%.
Manufacturability6
Rigid Clear-HT's machinability is good (65/100, better than 57% of polyurethane grades); weldability not recommended (5/100); formability not recommended (10/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other Rigid Clear grades and fills
Rigid Clear is also supplied in 9 other conditions. The full side-by-side table is on the Rigid Clear overview.
- STDDefaultDefault choice for clear prototype parts, housings and light pipes cast into silicone or machined-aluminium molds.40 MPa tensile
- D85Use for stiff clear panels, lenses and machined blanks where deflection must be minimal.55 MPa tensile
- HTSelect when parts see 100–120 °C, e.g. under-hood clear covers or parts that must survive paint bake.55 MPa tensile
- UVChoose for outdoor or backlit parts that must stay water-clear under sunlight or LED UV.45 MPa tensile
- AMChoose when the clear rigid part is printed directly (no tooling) and needs thermal post-cure for full properties.45 MPa tensile
- FRRequired for electrical enclosures and lighting parts needing a UL 94 V-0 rating; clarity drops to translucent.35 MPa tensile
- D70Pick when thin clear snap features or drop-impact survival matter more than stiffness.28 MPa tensile
Working with Rigid Clear-HT
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-HT — frequently asked
What is Rigid Clear-HT used for?
Rigid Clear-HT 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-HT?
Rigid Clear-HT has a typical yield strength of 38 MPa (5.51 ksi) and a tensile strength of 55 MPa (7.98 ksi) — weaker than 80% of polyurethane grades. Strength varies by condition: see the 10 listed tempers.
Is Rigid Clear-HT easy to machine?
Reasonably — machinability is rated good (65/100, better than 57% 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-HT 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-HT?
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-HT 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-HT?
Rigid Clear-HT is rated for continuous use to about 120°C (248 °F), and briefly to 150°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in Rigid Clear-HT?
Yes — Rigid Clear-HT 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.