Overview of Currently Used Borosilicate and Soda-Lime Glasses with Their Corresponding Classification in Established Standards and Pharmacopeia, Their Chemical Composition, and Their Physical Properties
| Borosilicate | Borosilicate | Borosilicate | Soda-Lime-Silica Glass | |
|---|---|---|---|---|
| 3.3 Group | 5.0 Group | 7.0 Group | ||
| ASTM E438 | Type I Class A | Type I Class B | Not described | Type II |
| ISO 12775 | Borosilicate glass 3.3 | Neutral glass | Not described | Alkali/alkaline earth silica glass |
| Glass Grain Test According to Current USP and Ph. Eur. | Type I | Type I | Type I | Type III |
| Composition | ||||
| SiO2 | 80–82 | 72–75 | 70–74 | 70–75 |
| B2O3 | 12–13 | 9–11 | 5–8 | 0–1 |
| Al2O3 | 2 | 5–7 | 4–6.5 | 2–4 |
| Na2O/K2O | 4 | 6–9 | 9–12 | 12–16 |
| MgO/CaO/BaO | 0 | 1–3 | 5–7 | 10–15 |
| Physical Data | ||||
| CTE [10−7 °C−1 (0°C;300°C)] as specified by ASTM E438 | 32–33 | 48–56 | Not described | 90–93 |
| CTE [10−6 K−1 (20°C;300°C)] as specified by ISO 12775 | 3.3 | 4.9–5.5 | Not described | 8–10 |
| CTE [10−6 K−1 (20°C;300°C)] as mainly found on the market | 3.3 | 4.9–5.4 | 6.3–7.0 | 7.1–9.3 |
| Hydrolytic resistance | High | High | Decreasing with increasing CTE | Low |