Bel-Art Scienceware Pyrex, Round Spinbar Magnetic Stir Bar, without Pivot Ring

The Bel-Art Scienceware Spinbar round stir bar has a clear heat-resistant Pyrex glass casing and an internal magnet made from alnico V (an alloy of aluminum, nickel, iron, and cobalt) for high-temperature laboratory stirring applications or where contamination is a concern. The round, cylindrical shape provides better centering and creates less turbulence than a multisided shape. The magnet sits inside a heat-resistant, nonporous, and nonabsorbent Pyrex glass capsule that can resist temperatures up to 525 degrees Fahrenheit (274 degrees Celsius). The bar's smooth surface provides quicker cleanup and less risk of cross-contamination than bars with pivot rings and allows the bar to spin on the bottom of the container for dispersing light sediment and air bubbles. The casing material meets the U.S. Pharmacopoeia specifications for Type I borosilicate glass.

Magnetic stir bars (sometimes called stirring bars, spin bars, or fleas) are used to stir a liquid or solution in biological, chemical, medical, and research laboratory applications. The stir bar is placed inside a container of liquid or solution that is seated on a magnetic stirrer (also called a magnetic mixer), which is a laboratory device that creates a rotating magnetic field using a rotating magnet or multiple stationary electromagnets. The rotating magnetic field causes the bar to spin, which stirs the liquid or solution. Stirring bars are offered in a variety of sizes and shapes, and they are encased in materials such as glass or plastic to help prevent contamination of the liquid or solution, to reduce friction, and to provide resistance to chemicals, abrasion, and heat. The bar may have a pivot ring or pivot point to minimize contact with the container, reduce friction, and improve its spinning. The size and shape of the container and the volume and viscosity of the liquid or solution to be stirred determine which stir bar shape, size, and casing will suit a particular application.

Bel-Art Products manufactures scientific products, including labware, testing equipment, and safety supplies, under the Bel-Art and Scienceware brands. The company, founded in 1946, is headquartered in Wayne, NJ.