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.
Ace Glass, Inc. Stirbar, PTFE, octagonal, blue, 12.7mm x 3.2mm
12.7mm x 3.2mm blue octagonal PTFE stirbar with pivot ring.
Chemglass Life Sciences 10mm PTFE Stirrer Bearing, 24/40, #018 Body O-Ring, #013 Bushing O-Ring
Grease-Free PTFE stirrer bearing for use under moderate vacuum. The bearing consists of a PTFE standard taper body, PEEK (Polyetheretherketone) compression cap, PTFE Insert/bushing and a Nylon loosening nut. The PTFE insert/bushing provides only glass and PTFE contact with the reaction. Loosening nut above the standard taper inner joint allows easy and quick removal. Supplied complete with a Perfluoro o-ring on the body and a Viton o-ring on the bushing.
Cole-Parmer Bel-Art Stir Bar Retriever, Flexible PTFE; 14-3/4" Long
Easily retrieve stir bars without spills or possible breakage. The alnico V magnet is completely enclosed in PTFE.
Research Products International Corp Octagon Magnetic Stirring Bar, 1 1/2x5/16
Octagon magnetic stirring bars with integral pivot ring are the most commonly used shape. Alnico magnet is encapsulated in FDA Grade, USP Class VI Teflon PTFE low friction coating; durable and inert. The interrupted profile provides greater surface area and added turbulence when compared to the smooth surface of cylindrical bars. Pivot ring aids in reducing friction and chattering . Stirring bars are autoclavable.
Research Products International Corp Flea Micro Magnetic Stirring Bar, 10 x 3 mm
Micro (Flea) magnetic stirring bars are designed for stirring small volumes in vessels such as vials, tubes and gradient makers. Particularly useful for environmental testing and life science applications in which small sample volumes need to be prepared and evaluated.
Biotage Magnetic Stir Bars, for 0.5-2 mL Microwave Reaction Vials 25/Case
Biotage Magnetic Stir Bars, for 0.5-2 mL Microwave Reaction Vials 25/Case
Biotage Magnetic Stir Bars, for 2-5 mL Microwave Reaction Vials 25/Case
Biotage Magnetic Stir Bars, for 2-5 mL Microwave Reaction Vials 25/Case
Thomas Scientific Stir Bar, Cylindrical, PTFE, 25mm, Bag of 2
Produced from PTFE For the stirring of liquids on magnetic stirrers and/or hotplate stirrers Strong alloy magnets sheathed in pure white inert PTFE Supplied in polarity aligned packs to ensure maximum coupling strength Resistant to virtually all chemical attack and temperatures up to 260°C
Sigma Aldrich Fine Chemicals Biosciences CORNING MAG STIR BAR RETRIEVER
NC3848688 CORNING MAG STIR BAR RETRIEVER
Chemglass Life Sciences Stir Bar, Magnetic, PTFE, Turbo, Rare Earth, Elliptical, 70 x 28mm
Exceptional strength coupled with almost total resistance to demagnetisation. Identified by an inert carbon black spot.
Sigma Aldrich Fine Chemicals Biosciences Rare earth extra power stir bars, 3/pk
Elliptical, diam. 6 mm, L 10 mm. Stirring bars using rare earth magnets have significantly increased magnetic strength compared to those using Alnico magnets, but more importantly they are almost totally resistant to demagnetisation.