What Is A Magnetic Hotplate Stirrer?

Thinking back to the days of my first chemistry lab, I remember my favorite experiments being the ones involving hot plate magnetic stirrers, because who doesn’t love the ability to create a near instantaneous vortex of ridiculously hot liquid? Hotplate magnetic stirrers have played a critical role in many different types of laboratories since their original design precisely a century ago, but how do they work?

What Is A Magnetic Stirrer?

Instead of manually mixing solutions, labs use machines with magnetic stirring units. As the name suggests, these units harness the power of magnetism for stirring purposes. A small magnetic bar coated in Teflon or glass, commonly referred to as a flea or stir bar, is submerged in the vessel containing the materials to be stirred.

This vessel, usually made of glass, is placed on the stirring unit’s platform. Underneath the platform, a rotating magnetic field is created by either a rotating magnet or by running electric current through stationary electromagnets. The magnetic stir bar interacts with the rotating magnetic field and is always trying to align itself with the orientation of the field. Because the magnetic field is rotating, the flea must also rotate to stay in alignment. This rotation of the flea is responsible for the stirring action. By controlling the speed of the rotating magnet, or the amount of current passing through the electromagnets, you can control the rate at which the flea spins, and speed of the vortex created in the vessel.

Whether you’re home brewing buffers or manufacturing at an industrial scale, finding the right magnetic stirrer for your workflow can increase your output and streamline your process. Make life easier for you and those in your lab – we can help you determine the right stirrer for your lab. No idea where to start?

Here are a few basic questions to ask to point you in the right direction for the correct Magnetic Stirrer.

What is the maximum volume you need to stir at once?

Although it seems simple, this question narrows your choices to specific capacity models. Manufacturers make small, large, and industrial-sized stirrers depending on the capacity you are expecting to stir. Knowing the max volume and the type of container you will be stirring in will help you decide the kind of stirrer you need.The MegaMag Genie Magnetic Stirrer is a heavy-duty stirrer with the capacity to mix up to 10 gallons and with the base to support the kind of container that can hold 10 gallons. If you need to mix that much liquid, then you can quickly close in on models like this one, or avoid them if you know you don’t need to stir that much.

Will I need to stir more than one container at a time?

There is no need to buy a magnetic stirrer for each vessel you need stirred – look for multi-place stirrers that can stir at multiple positions at once. Some stirrers can hold up to ten containers at once and others can stir as few as 4 spots. This one from Oxford Lab Products – the Oxford Magnetic Stirrer MS4 – is a 4-place stirrer that can handle up to 400 mL at each position. It has a digital display, so you can choose the exact speed setting (from 15 to 1200 RPM) and duration (1 to 99 minutes) you want every time. It also has a pulse function and can be used on timed or continuous modes. It’s also compact with no moving parts and spill resistant, so it’s built for everyday use

Do I need a digital or analog magnetic stirrer?

This answer to this question will vary from lab to lab, but essentially boils down to your budget and whether you need your stirring process to be documentable and repeatable. Analog stirrers are typically less expensive than digital models, but since you are adjusting the speed and/or temperature continuously using a knob, your protocol becomes less objective and harder to document and repeat. If you work in an academic lab, or don’t have strict regulatory requirements and SOP’s, you can probably get away with getting an analog stirrer. However, if you need to be able to record and repeat your protocol, a digital stirrer will allow you to choose a specific speed setting and temperature.

Will I need a temperature-controlled magnetic stirrer?

 As you might have gathered already, not all magnetic stirrers are created equal. Some of them are able to handle 10 gallons of liquid at once, some of them can stir multiple containers at once, and some of them can heat your solution while you stir. Most temperature-controlled magnetic stirrers can also function as a hot plate if you need to heat your sample but not stir it. Lastly, don’t forget to order extra stir bars! We can’t tell you how many times we’ve misplaced these or had them fall into the dusty crevice between the bench and the wall. Also, having a few different sizes helps when you need to stir in powders and liquids of different consistencies. Buy a few spares with your stirrer and keep them in a drawer to save yourself precious stirring time later. If all else fails, give one of our reps a call and we’ll point you in the right direction.

What Is a Hotplate Stirrer?

Hotplate Stirrers are a safer and more controllable alternative to Bunsen burners and other open flame apparatuses.The advantage of the hot plates comes not just in the form of improved performance through uniform and controlled heating but also in terms of overall safety. Today’s hotplates come in both analog and digital designs. Analog plates are controlled with a rotating dial while digital hot plates typically give you better temperature control. Hot plates with magnetic stirrer functions require a magnetic stir bar to put into a solution to effectively mix the solution during heating. Hence having a digital hot plate and magnetic stirrer allows for a more uniform and controlled environment for your solution. When it comes to materials, hot plates can be made from ceramic, aluminum, or enamel. An aluminum plate can distribute heat evenly, quickly, and efficiently. It is also easy to clean and maintain but does have a tendency to corrode. Ceramic and enamel are considered more conditioned to handle temperature fluctuations as well as resist strong chemicals. So which hotplate is right for you? Take a look at our comparison chart to find out!

Looking for a benchtop appliance to heat or mix your solutions there is an economical line of Benchmark Scientific Hotplate Stirrers and Labnet International brand of hot plates and hot plate/magnetic stirrers. Created to replace the open flame methodology of heating solutions in glassware, hot plates have come a long way!

Additional Benchmark Scientific Hotplates & Stirrers:

More Benchmark Accuris Balances

Questions to Consider when Choosing Your Magnetic Stirrers and Hotplates

Do you prefer digital or analog models?

What type of material best fits your lab (ceramic, corrosion resistant stainless steel, or other for the top plate)? Do you only need to stir solutions or do you need to heat and stir solutions? 

If you will be heating solutions, do you want an integrated temperature probe?

What size of vessels will you use?

Do you need a single or multi-place unit?

What volume of solution will you be producing at one time?

What Are Analytical Balances?

Analytical Laboratory Balances that are Reliable, Durable, and Precise. Pipette.com carries a wide variety of analytical balances to meet the varying needs of our customers. Analytical balances are designed to determine the exact mass of materials in liquid, paste, powder, or solid forms. Precision balances are an essential in almost any type of lab, no matter what sort of science that lab does. Measuring the mass of your samples requires complete accuracy, making sure you have the proper scale or balance for your specific work is fundamental in ensuring results. Pipette.com is an ISO 17025 Accredited Calibration Facility that calibrates and repairs all pipette brands and models with cloud based Calibration Management Software. Pipette.com is the largest independent pipette calibration facility on the West Coast. Pipette.com is also a distributor of several manufacturers of pipettes, pipette tips and lab equipment.