Stirring Bars and Rods
Stirring Bars and Rods
Products of various sizes, shapes, and material compositions designed to aid in manual or automatic stirring of laboratory solutions. Includes glass stirring rods, magnetic stir bars, and stir bar retrievers.
What Is a Magnetic Stir Bar?
Magnetic stir bars are stirrers or stirring hotplates used with magnets to mix a liquid or solution by creating a vortex.
A number of factors affect magnetic stir bar efficiency and effectiveness, including its size, shape, and material. Sizes (L x Diameter) range from 2 x 2 mm to 159 x 27 mm and shapes include:
- Polygonal or octagonal magnetic stir bars are the most common shapes; the multiple surfaces add turbulence to the mixing action
- Elliptical or egg-shapped stir bars work especially well with round-bottom flasks
- Wedge-shaped spin bars produce more significant turbulence for dissolving salts or in samples containing sediment
- Spin bars with fins or vanes, designed for smaller vessels, tubes, or cuvettes
- Micro (“flea”) stir bars for mixing extremely small samples
What Kind of Magnet Is Used?
Stir bar magnets are typically made from Alnico, a combination of aluminum and nickel. They may also be made from Samarium cobalt, a rare earth metal that produces the stronger magnetic force needed to mix very viscous substances.
Stir bar magnets are usually encapsulated in white or colored PTFE, hard plastic, or borosilicate glass, and coatings may meet FDA grade or USP requirements. PTFE is durable, inert, and can be autoclaved. Glass-encased cylindrical magnets are useful for high-temperature applications.
How Does It Work?
During the stirring process, integral or removable pivot rings on the stir bar reduce contact with the vessel to help avoid marring plastic surfaces. Some round stir bars have slightly raised ends that create a de facto pivot point, while others have more pronounced round centers that help to keep them in motion. Stir bars may be reusable or disposable.
Magnetic stir bars may be sold individually or in magnetic stir bar kits that include multiple bars in a range of sizes.
Fisherbrand™ Cylindrical Spinbar Magnetic Stirring Bar
Cylindrical magnetic stirring bars offer excellent centering and smooth-running characteristics.
Fisherbrand™ Polygon Stir Bars
Stirbars have polygon multifaceted surfaces that add turbulence relative to similar smooth size cylindrical bars.
Fisherbrand™ Octagonal Magnetic Stir Bar Kit
Includes 16 stir bars. Fisherbrand™ Octagonal Magnetic Stir Bar Kit offers a convenient kit packed in compartmented storage box.
Fisherbrand™ Micro Stir Bars
Micro Color-Coded Stirring Bar For stirring test tubes, micro-beakers, etc.
Fisherbrand™ Magnetic Stirring Bars
Stirbar assortments come in a convenient storage box. Fisherbrand™ Magnetic Stirring Bars contain PTFE encapsulated Alnico magnets and come in various sizes.
Fisherbrand™ Egg-Shaped Bars
Egg-shaped stirring bars are designed especially for use in round-bottom vessels as they spin unrestricted by the vessel contour.
Fisherbrand™ Magnetic Stir Bar Six Packs
These magnetic stirring bars are the most commonly used shape.
Fisherbrand™ PTFE Disposable Stir Bars
The multifaceted magnetic stirring bar surface adds turbulence relative to similar size smooth cylindrical stirring bars.
Fisherbrand™ Color-Coded Dumbbell-Style Stir Bars
Provide fast mixing action, strong turbulence, greater stability and less drifting at higher speeds.
Fisherbrand™ Magnetic Stir Bars with Vanes
Ensure thorough sample mixing in test tubes, micro vials and conical-bottom centrifuge tubes.
Fisherbrand™ PTFE Starburst Stirring Heads Individual Heads
Provide better mixing at bottom of vessel with less splashing.
Fisherbrand™ Micro Stir Bars
Stirring small volumes in vessels such as vials, tubes and grandient makers.
Fisherbrand™ Round Stir Bars with Removable Pivot Ring
Stirbars have polygon multifaceted surfaces that add turbulence relative to similar smooth size cylindrical bars.