Stirrers

Buying guide

The first number to settle is torque against viscosity, because it decides which half of the catalogue a buyer is even shopping in. A magnetic stirrer couples to a bar through the base of the vessel, and that coupling slips once the fluid is thick or the volume is large, so magnetic drives sit at the thin, low-volume end. An overhead stirrer drives a shaft directly and holds its speed under load, which is what gels, slurries, resins and multi-litre batches demand. Match the rated torque and the maximum stirring volume to the worst case the lab actually runs, not the average, and the rest of the specification follows from that one decision.

For units that also heat, the hotplate side carries its own figures: top plate material and temperature ceiling, whether a feedback probe is included, and how evenly the plate holds setpoint across its surface. Speed range matters more than top speed for most work, since reproducible low-speed mixing is harder to achieve than a fast spin. Chemical labs should check the plate and housing for solvent and acid resistance where spills are routine.

On a used stirrer the moving parts are what age. For an overhead unit, ask about bearing wear, chuck runout and motor hours, because a worn bearing shows up as wobble and noise long before it fails outright. For a magnetic or hotplate model, the plate coating and the electronics are the usual weak points, and a quick test at low and high speed reveals a failing speed controller. Confirm the probe and clamp accessories are present, since replacements can cost a meaningful fraction of a budget unit. Parts for most of these can be sourced via Questpair, and a warranty is arranged in consultation for the specific listing.

Price tracks that same split. A basic magnetic plate sits near the bottom of the range, while a sealed, explosion-rated overhead drive sits near the top, which is why the band here is so broad. 83 percent of the listings are used, and used units are listed below new, so a buyer working to a tight budget will find far more on the second-hand side. The brands that dominate, IKA, VWR, Thermo Fisher Scientific, Heidolph, Ohaus, appear across both new and used, which keeps a given model easy to compare on condition and price rather than on availability alone. Treat the listed price as the cost of the head unit and factor the stand, clamp and probe separately when they are not bundled, because a stirrer for sale without its support hardware is cheaper for a reason.

Types of Stirrers

Which stirrer types are listed?

Among the listings that specify a type, the most common are magnetic stirrers, laboratory stirrers and mixers, hotplate stirrers, and overhead and benchtop units. The magnetic stirrer is the default for routine work: a bar follows a rotating field under the plate, with no shaft entering the vessel, which keeps it clean and closed. A hotplate stirrer adds a heated top plate so dissolution and reaction steps run at temperature without a separate bath. The overhead stirrer is the heavy-duty alternative, driving an impeller on a shaft for viscous or large-volume batches that defeat magnetic coupling. The looser labels, laboratory stirrer, laboratory mixer and benchtop stirrer, group the mid-range general-purpose units that sit on a bench and serve whichever of those duties a lab meets most often. The line between them is torque and whether the drive touches the liquid, so a buyer picks by what the sample will tolerate and how thick it gets.

In the life sciences these units do the quiet, upstream work that everything else depends on. Magnetic stirring holds a buffer homogeneous during protein purification and keeps a culture medium mixed as it is made up; overhead stirring suspends cells gently in small-scale cell culture and mixes the viscous feeds of bioprocessing and biomanufacturing. A laboratory stirrer for cell culture media preparation and a magnetic stirrer for buffer homogenisation in molecular biology are everyday fixtures, as is a hotplate stirrer used for agar and reagent preparation in microbiology. They also support formulation and sample preparation ahead of electrophoresis, immunoassay and genomics workflows, where an evenly dissolved reagent is the precondition for a clean result rather than the result itself.

The brands behind the stirrer listings

The names that recur are IKA, VWR, Thermo Fisher Scientific, Heidolph, Ohaus. A concentrated field like this one works in the buyer's favour: parts and spare bars, chucks and probes are easier to source for a model that many labs already run, and a given series shows up often enough that condition and price can be compared across several listings rather than taken on a single one. The mix spans the whole range, from compact magnetic plates to sealed overhead drives, so the same maker often appears at both ends of the price band. That keeps cross-shopping straightforward, since a specialist can line up equivalent units from two makers on the figures that matter, torque, speed range and plate temperature, instead of on brand availability alone.

What a used stirrer costs here

Condition leans heavily toward the second-hand side: 83 percent of the listings are used, the remainder new. Prices run from EUR 9 to EUR 34.436, with an average around EUR 553. That spread covers the full catalogue, a bare magnetic plate at the low end and a large, feedback-controlled overhead system at the high end, so the figure to watch is where a given type sits within the band rather than the band itself. Used and refurbished units are listed below new across every type, which is why a buyer on a fixed budget finds the most choice there.