SF11
Grade · default condition
GB ZF11
SF11 = classic lead dense flint, fine annealed
Pick for legacy/high-index designs where the very soft, easily polished leaded flint and its exact dispersion curve must be reproduced.
Values for the SF11 condition
Other SF11 tempers and conditions
SF11 is listed in 2 conditions; see the grade overview at SF11.
- SF11
- N-SF11
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SF11DefaultThis page Classic lead dense flint, fine annealed | Pick for legacy/high-index designs where the very soft, easily polished leaded flint and its exact dispersion curve must be reproduced. | — | — | — | 450 HV | 0.74 W/m·K |
Lead- and arsenic-free equivalent | Pick for new RoHS/REACH-driven designs: identical nd 1.7847 / vd 25.7 optics at ~32 % lower density, harder surface, better blue transmission. | — | — | — | 590 HV | 0.95 W/m·K |
What is SF11?
SF11 is SF11 in the SF11 grade — pick for legacy/high-index designs where the very soft, easily polished leaded flint and its exact dispersion curve must be reproduced. SF11 has a tensile strength of 40 MPa (5.8 ksi), weaker than 65% of glass grades. Elongation at break is 0% and the elastic modulus is 66 GPa (9.57 Msi). SF11 has a density of 4.74 g/cm³ (0.171 lb/in³), heavier than 85% of glass grades.
Limitations
- Poor heat conductor — 0.74 W/m·K (0.426 BTU/hr·ft·°F), worse than 93% of glass grades
- Heavy — 4.74 g/cm³ (0.171 lb/in³), worse than 85% of glass grades
- Needs corrosion protection — 45/100, worse than 84% of glass grades
SF11 properties
Typical room-temperature values for SF11; 12 are specific to this condition. Other listed values are SF11 reference data and may not represent this condition. Bars are the position among glass grades.
Physical4
SF11 has a density of 4.74 g/cm³ (0.171 lb/in³), heavier than 85% of glass grades.
Mechanical12
SF11 has a tensile strength of 40 MPa (5.8 ksi), weaker than 65% of glass grades. Elongation at break is 0% and the elastic modulus is 66 GPa (9.57 Msi).
Thermal5
SF11 is rated for continuous service to 400°C (752 °F). It conducts heat at 0.74 W/m·K (0.426 BTU/hr·ft·°F), worse than 93% of glass grades. Thermal expansion is 6.1 µm/m·K (3.39 µin/in·°F).
Electrical5
SF11 is an electrical insulator with a dielectric strength of 15 kV/mm (381 V/mil) and a resistivity of 1×10¹² Ω·m.
Chemical & Environmental2
Corrosion resistance is fair (45/100), worse than 84% of glass grades.
Sustainability4
Producing a kilogram of SF11 takes about 45 MJ of energy and emits 3.2 kg of CO₂ — less than 58% of glass grades. Typical recycled content is 5%.
Manufacturability2
SF11's machinability is poor (25/100, better than 63% of glass grades).
Common Calculations4
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with SF11
Is SF11 easy to machine?
No conventional machining — diamond core-drilling, curve generating, loose-abrasive grinding then pitch/polyurethane polishing with cerium oxide; the soft leaded surface scratches and sleeks easily, so keep swarf clean.
Can SF11 be welded?
Not weldable; joining is by optical contacting or UV/thermal-cure optical cement (NOA-type) to matched-CTE partner glasses.
Can SF11 be formed, bent or molded?
Formed by melting and precision gob pressing or by re-heat pressing of blanks near 620–700 °C, followed by fine (precision) annealing near Tg ≈ 505 °C at a few °C/h to hold refractive index and low stress birefringence.
What surface finishes work on SF11?
Polish to λ/4 or better, then AR-coat by e-beam/IAD — coating temperature must stay well under Tg; edges are blackened and lenses centered on a bell chuck.
SF11 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 |
|---|---|---|
| PbOapproximate; exact optical-melt batch is proprietary (leaded SF11/ZF11 only) | 45 – 55 | 51 |
| K2Oalkali modifier | 4 – 10 | 8 |
| Na2O | 0 – 3 | 1 |
| other oxides (BaO, ZnO, As2O3/Sb2O3 finiN-SF11 replaces PbO with TiO2/Nb2O5/ZrO2-type high-index oxides and is As/Pb-free | 0 – 5 | 2 |
| SiO2network former | ≥ 28 (balance) | — |
SF11 — frequently asked
What is SF11 used for?
SF11 is typically used for high-index camera lenses, prisms and beam splitters. In short: very high refractive index; leaded SF11, N-SF11 alternative.
What is the tensile strength of SF11?
SF11 has a typical tensile strength of 40 MPa (5.8 ksi) — weaker than 65% of glass grades. Strength varies by condition: see the 2 listed tempers.
Is SF11 easy to machine?
Not especially — machinability is rated poor (25/100, better than 63% of glass grades). No conventional machining — diamond core-drilling, curve generating, loose-abrasive grinding then pitch/polyurethane polishing with cerium oxide; the soft leaded surface scratches and sleeks easily, so keep swarf clean.
Can SF11 be welded?
Not weldable; joining is by optical contacting or UV/thermal-cure optical cement (NOA-type) to matched-CTE partner glasses.
What surface finishes work on SF11?
Polish to λ/4 or better, then AR-coat by e-beam/IAD — coating temperature must stay well under Tg; edges are blackened and lenses centered on a bell chuck.
Can SF11 be formed, bent or molded?
Formed by melting and precision gob pressing or by re-heat pressing of blanks near 620–700 °C, followed by fine (precision) annealing near Tg ≈ 505 °C at a few °C/h to hold refractive index and low stress birefringence.
What is the maximum service temperature of SF11?
SF11 is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- Optical Glass Data Sheets (SF11 / N-SF11) — SCHOTT AG (2023)
- Optical Glass Catalog (ZF / H-ZF dense flint series) — CDGM (2023)
- Engineered Materials Handbook Vol.4: Ceramics and Glasses — ASM International (1991)
- RefractiveIndex / optical glass dispersion data (Sellmeier constants) — public optical glass databases (2024)
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.