Magnetic stirring bars: choise, tolerances and finishing

Improperly selected stirring bars are often cause flickering of the bars in the vessel, respectively ineffective mixing of the product.
You can find an overview of the most common stirring bars here below:

They are the most commonly used magnetic stirring bars. Due to their simple shape they can be offered at very attractive prices. Cylindrical magnetic stirring bars offer excellent centering and smooth running characteristics.

These magnetic stirring bars have very smooth and seamless surfaces. No substance can penetrate into their surfaces and thus, all following processes are not affected by any „carry-over“. They are mainly used for high-purity work or trace analysis.

Due to special magnetic material, their torque loads are larger than those of conventional magnetic stirring bars. Power magnetic stirring bars are mainly used for agitating viscous liquids or for bridging larger distances between the magnetic stirring machine and the magnetic stirring bar.

Their interrupted surface provides greater surface area and added turbulence. Only their pivot ring and one end of the magnetic stirring bar touch the bottom of the vessel. Therefore these magnetic stirring bars have a more steady spinning position and a better longevity.

They are particularly suitable for big vessels due to the high magnetic force. Solids are released or removed from the bottom of the vessel.

They are particularly suitable for round-bottom flasks. Their shape mimics that of the flasks and assures complete mixing. Those magnetic stirring bars have an egg-shaped magnetic core which assures a better force transmission than a cylindrical core.

Such magnets are useful for mixing reagents which resist dissolving or for avoiding any residues at the bottom of the vessels. They provide strong turbulence at relatively low speeds.

They have a non-porous and smooth glass-coating. All following processes are not affected by any carry-over. There is an increased abrasion between glass vessels and glass stirring bars.

Optimum stirring in tall, narrow diameter vessels. Ideal stirring bar for cuvettes or test tubes.

These magnetic stirring bars provide better stirring action and a more stable spinning position due to the punctual position.