## Common ground
All options are types of evaporating dishes, used for concentrating or drying substances by evaporation.
## Options at a glance
**3926.90 – Plastic**
- **Defining trait:** Made from plastic, typically resistant to chemicals and lightweight.
- **Typical examples:** Polypropylene or polyethylene evaporating dishes.
- **Best fit when:** Used with non-corrosive liquids and in low-temperature applications.
**6903 – Refractory ceramic**
- **Defining trait:** Made from high-temperature-resistant ceramic, suitable for direct flame heating.
- **Typical examples:** Porcelain or alumina-based dishes used in labs or industrial settings.
- **Best fit when:** Requires high heat resistance or exposure to open flames.
**6909.1X – Ceramic**
- **Defining trait:** General ceramic material, often non-refractory; less heat-resistant than refractory types.
- **Typical examples:** Standard ceramic lab dishes for mild heating.
- **Best fit when:** Used in standard lab procedures without extreme temperatures.
**7017 – Glass**
- **Defining trait:** Made from borosilicate or soda-lime glass, transparent and chemically inert.
- **Typical examples:** Beaker-like dishes for visible evaporation processes.
- **Best fit when:** Transparency is needed to monitor the process or for high chemical resistance.
## Key differences
| Feature | Plastic (3926.90) | Refractory Ceramic (6903) | Ceramic (6909.1X) | Glass (7017) |
|---------------------|-------------------|----------------------------|--------------------|--------------|
| Heat resistance | Low | Very high | Moderate | High |
| Transparency | Opaque | Opaque | Opaque | Transparent |
| Chemical resistance | Good (to many) | Excellent | Good | Excellent |
| Flame exposure | Not safe | Safe | Not safe | Not safe |
## How to choose
- Is the dish used with strong acids or bases? → 7017 or 6903
- Does it need to withstand direct flame or high heat? → 6903
- Must you see the process inside? → 7017
- Is it for low-cost, disposable use? → 3926.90
## Overlaps & pitfalls
- Refractory ceramic (6903) and general ceramic (6909.1X) may overlap in appearance; the key difference is heat resistance.
- Glass (7017) and plastic (3926.90) both resist many chemicals, but glass allows visibility and better heat tolerance.
- If unsure, prioritize the **main function**: flame use → 6903; visibility → 7017; low cost → 3926.90; general lab use → 6909.1X