PTFE Coating
Resistant to acids, alkalis and most organic solvents. The easy-to-clean surface is suitable for routine chemical experiments.
Laboratory Mixing Accessories
Laboratory Magnetic Stir Bars
Types A, B and C
Featuring a chemically resistant PTFE coating and an encapsulated magnetic core, these stir bars provide stable, low-noise mixing without a mechanical drive shaft contacting the liquid. Multiple sizes support everyday laboratory work with small-volume samples, standard beakers and larger vessels.
Product Overview
Type A, B and C magnetic stir bars are rotors used with laboratory magnetic stirrers. The stirrer generates a rotating magnetic field that drives the bar at the bottom of the vessel, creating liquid flow to improve mass transfer, dissolution and mixing.
Multiple Sizes
Select suitable dimensions for small-volume samples, beakers, reagent bottles and other common laboratory vessels.
Stable Mixing
Smooth profiles help reduce snagging and magnetic decoupling, supporting continuous stirring under suitable operating conditions.
Type Comparison
| Type | Design Features | Recommended Vessels | Typical Uses |
|---|---|---|---|
| Type A | General-purpose cylindrical profile with rounded transitions | Test tubes, sample vials and small beakers | Dissolution, dilution and routine low- to medium-speed stirring |
| Type B | Balanced contact length and magnetic coupling for stable mixing | Beakers, Erlenmeyer flasks and reaction bottles | Buffer preparation, culture media and synthetic reaction mixtures |
| Type C | Longer contact surface with a design intended to improve stability | Larger beakers and flat-bottom vessels | Larger liquid volumes and higher-viscosity mixtures |
Technical Specifications
| Parameter | Type A | Type B | Type C |
|---|---|---|---|
| Coating Material | PTFE (polytetrafluoroethylene) | PTFE (polytetrafluoroethylene) | PTFE (polytetrafluoroethylene) |
| Internal Structure | Encapsulated magnetic core | Encapsulated magnetic core | Encapsulated magnetic core |
| Available Dimensions | Approximately 3 × 5 mm to 20 × 60 mm | Approximately 3 × 5 mm to 20 × 60 mm | Approximately 3 × 5 mm to 20 × 60 mm |
| Operating Temperature | Suitable for routine heated laboratory stirring. The actual temperature limit depends on the PTFE coating, vessel and stirrer configuration. | ||
| Chemical Compatibility | Resistant to most acids, alkalis, salt solutions and common organic solvents. Verify compatibility before use with strongly oxidizing media or extreme high-temperature conditions. | ||
| Selection Criteria | Consider vessel base area, liquid volume, viscosity and the magnetic field strength of the stirrer. | ||
Dimensions, pack quantities and magnetic grades depend on the selected SKU. Refer to the corresponding product listing and physical label for exact specifications.
Applications
Solution Preparation
Accelerate the dissolution of powders, salts and buffer components while reducing manual shaking.
Synthesis & Reactions
Maintain uniform mixing during temperature-controlled experiments, dropwise addition and reflux.
Sample Preparation
Support extraction, dilution, dispersion and sample homogenization before analysis.
How to Use
- Select an appropriate stir bar length based on vessel diameter and liquid volume. Ensure the bar can rotate freely at the bottom of the vessel.
- Place the stir bar at the bottom of the vessel, add the liquid and position the vessel centrally on the magnetic stirrer.
- Start at a low speed. Once stable magnetic coupling is established, increase the speed gradually.
- Stop stirring after the experiment. Remove the bar using a stir bar retriever or suitable tweezers, then rinse and dry it.
Care & Precautions
- Avoid high-speed operation without liquid, which may cause magnetic decoupling, impact against the vessel or wear of the PTFE surface.
- A bar that is too small may provide insufficient coupling, while an oversized bar may encounter rotational resistance. Match the dimensions to the vessel.
- Do not scrape the PTFE coating with sharp tools. After cleaning, inspect for cracks, coating damage or an exposed magnetic core.
- Confirm material compatibility before use with strongly oxidizing media, extreme temperatures or high-pressure conditions.
Frequently Asked Questions
How do I choose between Types A, B and C?
First select the length based on vessel base area and liquid volume, then consider viscosity and target speed. Type A is a common starting point for small vessels, Type B suits routine beaker applications, and Type C may be considered for larger volumes or higher-viscosity mixtures.
Why does the stir bar jump or stop rotating?
Common causes include excessive starting speed, an unsuitable bar-to-vessel size match, an off-center vessel or excessive liquid viscosity. Reduce the speed, recenter the vessel and select a more suitable stir bar size.
How should I clean the stir bar after use?
Rinse with clean water or a cleaning agent compatible with the experimental medium. Wipe gently if necessary and dry thoroughly. Avoid prolonged soaking in incompatible, strongly oxidizing media.
Can I continue using a bar with a damaged PTFE coating?
Continued use is not recommended. A damaged coating may expose the magnetic core, contaminate the sample and reduce chemical resistance. Replace the stir bar promptly.
