## Common ground
All are laboratory mortars used for grinding, mixing, or crushing solid samples.
## Options at a glance
**3926.90 – Plastic**
- **Defining trait:** Made from non-reactive, lightweight plastic; resistant to acids and chemicals.
- **Typical examples:** Polyethylene or polypropylene pestles and mortars.
- **Best fit when:** Handling corrosive materials or when low weight and shatterproof design are needed.
**6903 – Refractory ceramic**
- **Defining trait:** Designed to withstand high temperatures and thermal shock; highly durable.
- **Typical examples:** Alumina or silica-based mortars for high-temp applications.
- **Best fit when:** Used in high-temperature processes (e.g., calcination) or with reactive materials.
**6909.1X – Ceramic**
- **Defining trait:** General-purpose ceramic; less heat-resistant than refractory types but still chemically inert.
- **Typical examples:** Standard porcelain mortars for routine lab use.
- **Best fit when:** Daily grinding of non-corrosive, room-temperature samples.
**7017 – Glass**
- **Defining trait:** Transparent, chemically inert, and easy to clean; fragile and not heat-resistant.
- **Typical examples:** Borosilicate glass mortars for sensitive or visual analysis.
- **Best fit when:** Need visibility during mixing or handling of non-abrasive, non-thermal samples.
## Key differences
| Feature | Plastic | Refractory Ceramic | Ceramic | Glass |
|--------------------|---------------|--------------------|-------------|--------------|
| Heat resistance | Low | Very high | Medium | Low |
| Chemical resistance| High (most) | Very high | High | High |
| Visibility | None | None | None | Yes |
| Fragility | Low (shatterproof) | High (hard) | Medium | High |
## How to choose
- Is the mortar used at high temperatures? → 6903
- Does it need to be transparent for visual monitoring? → 7017
- Is chemical resistance and low weight most important? → 3926.90
- Is it for general, everyday use with no extreme conditions? → 6909.1X
## 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 offer chemical inertness but differ in fragility and visibility.
- If a product is both heat-resistant and transparent, it likely belongs to 6903 (if refractory) or 7017 (if glass). Prioritize the **main function**: use 6903 for high-temp work, 7017 for visibility