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.
Sigma Aldrich Fine Chemicals Biosciences SpinbarR magnetic stirring
Very small efficient stirring bars. Ideal for vials micro test tubes centrifuge tube mixing etc.PTfE(R) PTfE coatedALNICO V coated magnet
Hach Company Stir Bar, 8 x 3 mm - replacement for 5500sc Ammonia Monochloramine Analyzer
Replacement magnetic stir bar for use with the 5500sc Ammonia Monochloramine Analyzer. It provides consistent mixing in the sample chamber to support accurate, continuous measurements; regular replacement is recommended to maintain analyzer performance.
- Dimensions: 8 x 3 mm.
- Suggested replacement schedule: 6 months.
- Material: not specified by the manufacturer.
- Function: maintains proper mixing in the sample chamber.
Cole-Parmer Starburst Magnetic Stirring Heads, 3/4" x 3/4"; 1/Pk
Stirring heads produce a large vortex for quick, efficient mixing—conserve both energy and valuable lab time. Powerful alnico V magnet is coated with PTFE for purity and excellent chemical resistance. Fully autoclavable.
Andwin Scientific SPINBAR DISP 1/2D X 1/2L
The Spinbar are disposable, multifaceted stir bars that increase turbulence relative to similar size smooth cylindrical stirring bars. This product is recommended for use in single use applications, such as mixing radioactive reagents. The stirring
V&P Scientific Inc STIR ELEMENT, SUPER DISCS, Stainless Steel, Parylene C Coated, Used in Microplates, Syringes, Tubes/Vials, 1000/pack
STIR ELEMENT, SUPER DISCS, Stainless Steel, Parylene C Coated, 8.0mm Diameter, 0.7mm Height, 200°C Max Operating Temp for Coating
Cole-Parmer Disposable Stir Bar, PTFE-coated alnico V magnet, 1/2" x 1/8", 100/pk
These stir bars are ideal for demanding chemical and biological applications where cross-contamination is a concern. They have strong alnico V magnets with a one-piece coating of PTFE and priced to be disposable. The stir bars are offered in a convenient bulk package of 100 stir bars.
