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 Rare earth extra power stir bars Elliptical, diam. 14 mm, L 25 mm | 3EA
Rare earth extra power stir bars Elliptical, diam. 14 mm, L 25 mm | 3EA
Chemglass Life Sciences Stirring Bar, Plain, 10 x 6mm, Magnetic, PTFE
Stirring Bar, Plain, 10 x 6mm, Magnetic, PTFE
Cowie Technology Corporation REMOVABLE RINGSTIRL102MMD16MM
This item has a minimum qty of 7 per supplier requirements.
Stirbar, removable ring, length 102 mm, diameter 16 mm
Cowie Technology Corporation OVAL STIRBAR 30MM L 10MM D
This item has a minimum qty of 46 per supplier requirements.
Stirbar, oval, length 30 mm, diameter 10 mm
Cowie Technology Corporation OCTAHEDRAL STIR 75MM L 13MM D
This item has a minimum qty of 16 per supplier requirements.
Stirbar, octahedral, length 75 mm, diameter 13 mm
Spectrum Pharma Quip Specialties Inc S BAR OCT 1/2 X3 100/CS
SPECTRUM PHARMA-QUIP SPECIALITES STIR BAR, OCTAGONAL, (13MM X 75MM), 1/2 in. X 3 in. 100/CS
Chemglass Life Sciences Chemglass Stirrer Bar, Magnetic, PTFE, Double Crosshead, 15 x 22 mm
PTFE double crosshead magnetic stirrer bar designed for use in tube-like containers and general laboratory stirring applications. The crosshead shape improves vortex formation and stability while the PTFE coating resists chemical attack and high temperatures.
- Compact 15 x 22 mm size suitable for small vessels and tubes.
- PTFE construction provides chemical resistance and temperature stability.
- Double crosshead shape improves turbulence and mixing efficiency.
- Magnetic core ensures reliable coupling with magnetic stir plates.
- Sold individually for flexible replacement and inventory use.