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.
Research Products International Corp Rare Earth Cobalt Spinbar, Octagon, Teflon Coated, 1 x 3/8 Inches
Reduce frequency of spinout in viscous solutions or when stirring at high speeds. The high magnetic field strength of Samarium Cobalt (Rare Earth) magnets can provide up to three times stronger coupling vs. Alnico magnetic stirring bars. Stronger coupling with the drive magnet keeps the stirring bar centered and rotating effectively. Octagon shape with pivot ring creates strong turbulence with minimal chattering and friction. Encapsulated in bright green, FDA grade, USP Class VI Teflon PTFE; easy to differentiate from other stirring bars. Autoclave safe.
Bellco Glass, Inc. PTFE Stirring Bar,76.2mm
Molded, seamless Teflon construction ideal for procedures using all bellco magnetic stirrers. Excellent for mixing media and buffer solutions. Size: 76.2 x 12.1mm Case qty: 3
Ace Glass, Inc. Stirbar, PTFE, x shape, for microscale vials, 25.4mmx25.4mm
Stirbar, PTFE, x shape, for microscale vials, 25.4mmx25.4mm
Analytical Sales & Services Well Tray Loaded with 8x30 Shell Vials, with 99685 Silicone Cap Mat, and 13258 Stir Bars
Well Tray Loaded with 8x30 Shell Vials, with 99685 Silicone Cap Mat, and 13258 Stir Bars
Cole-Parmer DWK Life Sciences (Kimble) Stir Rod, Glass, 5 mm dia X 150 mm L, 25/pk
Manufactured with borosilicate glass with rounded annealed ends. Stir rods are highly chemical resistant and withstands temperatures to 400 F (205)C. Autoclavable.
Sigma Aldrich Fine Chemicals Biosciences SpinbarR disposable magnet
for single-use application where efficiency and cross-contamination are a concern. Alnico V magnet.
Sigma Aldrich Fine Chemicals Biosciences SpinbarR magnetic stir bar1EA
Leakproof seamless polished and contains a permanent Alnico V magnet. Egg-shape bar is designed especially for use in round-bottom vessels.